This patch series introduces a scalable and lockless ring-array based
object pool to improve scalability of kretprobed routines.
v11:
*) patchset rebased to branch probes/core of linux-trace.git
*) objpool: objpool_fini optimized for better code readability
*) test_objpool: asynchronous releasing of objpool now covered
wuqiang.matt (5):
lib: objpool added: ring-array based lockless MPMC
lib: objpool test module added
kprobes: kretprobe scalability improvement with objpool
kprobes: freelist.h removed
MAINTAINERS: objpool added
MAINTAINERS | 7 +
include/linux/freelist.h | 129 --------
include/linux/kprobes.h | 11 +-
include/linux/objpool.h | 176 ++++++++++
include/linux/rethook.h | 16 +-
kernel/kprobes.c | 93 +++---
kernel/trace/fprobe.c | 32 +-
kernel/trace/rethook.c | 90 +++--
lib/Kconfig.debug | 11 +
lib/Makefile | 4 +-
lib/objpool.c | 286 ++++++++++++++++
lib/test_objpool.c | 689 +++++++++++++++++++++++++++++++++++++++
12 files changed, 1270 insertions(+), 274 deletions(-)
delete mode 100644 include/linux/freelist.h
create mode 100644 include/linux/objpool.h
create mode 100644 lib/objpool.c
create mode 100644 lib/test_objpool.c
--
2.40.1
kretprobe is using freelist to manage return-instances, but freelist,
as LIFO queue based on singly linked list, scales badly and reduces
the overall throughput of kretprobed routines, especially for high
contention scenarios.
Here's a typical throughput test of sys_prctl (counts in 10 seconds,
measured with perf stat -a -I 10000 -e syscalls:sys_enter_prctl):
OS: Debian 10 X86_64, Linux 6.5rc7 with freelist
HW: XEON 8336C x 2, 64 cores/128 threads, DDR4 3200MT/s
1T 2T 4T 8T 16T 24T
24150045 29317964 15446741 12494489 18287272 17708768
32T 48T 64T 72T 96T 128T
16200682 13737658 11645677 11269858 10470118 9931051
This patch introduces objpool to replace freelist. objpool is a
high performance queue, which can bring near-linear scalability
to kretprobed routines. Tests of kretprobe throughput show the
biggest ratio as 159x of original freelist. Here's the result:
1T 2T 4T 8T 16T
native: 41186213 82336866 164250978 328662645 658810299
freelist: 24150045 29317964 15446741 12494489 18287272
objpool: 23926730 48010314 96125218 191782984 385091769
32T 48T 64T 96T 128T
native: 1330338351 1969957941 2512291791 2615754135 2671040914
freelist: 16200682 13737658 11645677 10470118 9931051
objpool: 764481096 1147149781 1456220214 1502109662 1579015050
Testings on 96-core ARM64 output similarly, but with the biggest
ratio up to 448x:
OS: Debian 10 AARCH64, Linux 6.5rc7
HW: Kunpeng-920 96 cores/2 sockets/4 NUMA nodes, DDR4 2933 MT/s
1T 2T 4T 8T 16T
native: . 30066096 63569843 126194076 257447289 505800181
freelist: 16152090 11064397 11124068 7215768 5663013
objpool: 13997541 28032100 55726624 110099926 221498787
24T 32T 48T 64T 96T
native: 763305277 1015925192 1521075123 2033009392 3021013752
freelist: 5015810 4602893 3766792 3382478 2945292
objpool: 328192025 439439564 668534502 887401381 1319972072
Signed-off-by: wuqiang.matt <[email protected]>
---
include/linux/kprobes.h | 11 ++---
include/linux/rethook.h | 16 ++-----
kernel/kprobes.c | 93 +++++++++++++++++------------------------
kernel/trace/fprobe.c | 32 ++++++--------
kernel/trace/rethook.c | 90 ++++++++++++++++++---------------------
5 files changed, 98 insertions(+), 144 deletions(-)
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 85a64cb95d75..365eb092e9c4 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -26,8 +26,7 @@
#include <linux/rcupdate.h>
#include <linux/mutex.h>
#include <linux/ftrace.h>
-#include <linux/refcount.h>
-#include <linux/freelist.h>
+#include <linux/objpool.h>
#include <linux/rethook.h>
#include <asm/kprobes.h>
@@ -141,7 +140,7 @@ static inline bool kprobe_ftrace(struct kprobe *p)
*/
struct kretprobe_holder {
struct kretprobe *rp;
- refcount_t ref;
+ struct objpool_head pool;
};
struct kretprobe {
@@ -154,7 +153,6 @@ struct kretprobe {
#ifdef CONFIG_KRETPROBE_ON_RETHOOK
struct rethook *rh;
#else
- struct freelist_head freelist;
struct kretprobe_holder *rph;
#endif
};
@@ -165,10 +163,7 @@ struct kretprobe_instance {
#ifdef CONFIG_KRETPROBE_ON_RETHOOK
struct rethook_node node;
#else
- union {
- struct freelist_node freelist;
- struct rcu_head rcu;
- };
+ struct rcu_head rcu;
struct llist_node llist;
struct kretprobe_holder *rph;
kprobe_opcode_t *ret_addr;
diff --git a/include/linux/rethook.h b/include/linux/rethook.h
index 26b6f3c81a76..ce69b2b7bc35 100644
--- a/include/linux/rethook.h
+++ b/include/linux/rethook.h
@@ -6,11 +6,10 @@
#define _LINUX_RETHOOK_H
#include <linux/compiler.h>
-#include <linux/freelist.h>
+#include <linux/objpool.h>
#include <linux/kallsyms.h>
#include <linux/llist.h>
#include <linux/rcupdate.h>
-#include <linux/refcount.h>
struct rethook_node;
@@ -30,14 +29,12 @@ typedef void (*rethook_handler_t) (struct rethook_node *, void *, unsigned long,
struct rethook {
void *data;
rethook_handler_t handler;
- struct freelist_head pool;
- refcount_t ref;
+ struct objpool_head pool;
struct rcu_head rcu;
};
/**
* struct rethook_node - The rethook shadow-stack entry node.
- * @freelist: The freelist, linked to struct rethook::pool.
* @rcu: The rcu_head for deferred freeing.
* @llist: The llist, linked to a struct task_struct::rethooks.
* @rethook: The pointer to the struct rethook.
@@ -48,20 +45,16 @@ struct rethook {
* on each entry of the shadow stack.
*/
struct rethook_node {
- union {
- struct freelist_node freelist;
- struct rcu_head rcu;
- };
+ struct rcu_head rcu;
struct llist_node llist;
struct rethook *rethook;
unsigned long ret_addr;
unsigned long frame;
};
-struct rethook *rethook_alloc(void *data, rethook_handler_t handler);
+struct rethook *rethook_alloc(void *data, rethook_handler_t handler, int size, int num);
void rethook_stop(struct rethook *rh);
void rethook_free(struct rethook *rh);
-void rethook_add_node(struct rethook *rh, struct rethook_node *node);
struct rethook_node *rethook_try_get(struct rethook *rh);
void rethook_recycle(struct rethook_node *node);
void rethook_hook(struct rethook_node *node, struct pt_regs *regs, bool mcount);
@@ -98,4 +91,3 @@ void rethook_flush_task(struct task_struct *tk);
#endif
#endif
-
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index ca385b61d546..075a632e6c7c 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1877,13 +1877,27 @@ static struct notifier_block kprobe_exceptions_nb = {
#ifdef CONFIG_KRETPROBES
#if !defined(CONFIG_KRETPROBE_ON_RETHOOK)
+
+/* callbacks for objpool of kretprobe instances */
+static int kretprobe_init_inst(void *nod, void *context)
+{
+ struct kretprobe_instance *ri = nod;
+
+ ri->rph = context;
+ return 0;
+}
+static int kretprobe_fini_pool(struct objpool_head *head, void *context)
+{
+ kfree(context);
+ return 0;
+}
+
static void free_rp_inst_rcu(struct rcu_head *head)
{
struct kretprobe_instance *ri = container_of(head, struct kretprobe_instance, rcu);
+ struct kretprobe_holder *rph = ri->rph;
- if (refcount_dec_and_test(&ri->rph->ref))
- kfree(ri->rph);
- kfree(ri);
+ objpool_drop(ri, &rph->pool);
}
NOKPROBE_SYMBOL(free_rp_inst_rcu);
@@ -1892,7 +1906,7 @@ static void recycle_rp_inst(struct kretprobe_instance *ri)
struct kretprobe *rp = get_kretprobe(ri);
if (likely(rp))
- freelist_add(&ri->freelist, &rp->freelist);
+ objpool_push(ri, &rp->rph->pool);
else
call_rcu(&ri->rcu, free_rp_inst_rcu);
}
@@ -1929,23 +1943,12 @@ NOKPROBE_SYMBOL(kprobe_flush_task);
static inline void free_rp_inst(struct kretprobe *rp)
{
- struct kretprobe_instance *ri;
- struct freelist_node *node;
- int count = 0;
-
- node = rp->freelist.head;
- while (node) {
- ri = container_of(node, struct kretprobe_instance, freelist);
- node = node->next;
-
- kfree(ri);
- count++;
- }
+ struct kretprobe_holder *rph = rp->rph;
- if (refcount_sub_and_test(count, &rp->rph->ref)) {
- kfree(rp->rph);
- rp->rph = NULL;
- }
+ if (!rph)
+ return;
+ rp->rph = NULL;
+ objpool_fini(&rph->pool);
}
/* This assumes the 'tsk' is the current task or the is not running. */
@@ -2087,19 +2090,17 @@ NOKPROBE_SYMBOL(__kretprobe_trampoline_handler)
static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
{
struct kretprobe *rp = container_of(p, struct kretprobe, kp);
+ struct kretprobe_holder *rph = rp->rph;
struct kretprobe_instance *ri;
- struct freelist_node *fn;
- fn = freelist_try_get(&rp->freelist);
- if (!fn) {
+ ri = objpool_pop(&rph->pool);
+ if (!ri) {
rp->nmissed++;
return 0;
}
- ri = container_of(fn, struct kretprobe_instance, freelist);
-
if (rp->entry_handler && rp->entry_handler(ri, regs)) {
- freelist_add(&ri->freelist, &rp->freelist);
+ objpool_push(ri, &rph->pool);
return 0;
}
@@ -2193,7 +2194,6 @@ int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long o
int register_kretprobe(struct kretprobe *rp)
{
int ret;
- struct kretprobe_instance *inst;
int i;
void *addr;
@@ -2227,19 +2227,12 @@ int register_kretprobe(struct kretprobe *rp)
rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
#ifdef CONFIG_KRETPROBE_ON_RETHOOK
- rp->rh = rethook_alloc((void *)rp, kretprobe_rethook_handler);
- if (!rp->rh)
- return -ENOMEM;
+ rp->rh = rethook_alloc((void *)rp, kretprobe_rethook_handler,
+ sizeof(struct kretprobe_instance) +
+ rp->data_size, rp->maxactive);
+ if (IS_ERR(rp->rh))
+ return PTR_ERR(rp->rh);
- for (i = 0; i < rp->maxactive; i++) {
- inst = kzalloc(struct_size(inst, data, rp->data_size), GFP_KERNEL);
- if (inst == NULL) {
- rethook_free(rp->rh);
- rp->rh = NULL;
- return -ENOMEM;
- }
- rethook_add_node(rp->rh, &inst->node);
- }
rp->nmissed = 0;
/* Establish function entry probe point */
ret = register_kprobe(&rp->kp);
@@ -2249,24 +2241,18 @@ int register_kretprobe(struct kretprobe *rp)
rp->rh = NULL;
}
#else /* !CONFIG_KRETPROBE_ON_RETHOOK */
- rp->freelist.head = NULL;
rp->rph = kzalloc(sizeof(struct kretprobe_holder), GFP_KERNEL);
if (!rp->rph)
return -ENOMEM;
- rp->rph->rp = rp;
- for (i = 0; i < rp->maxactive; i++) {
- inst = kzalloc(struct_size(inst, data, rp->data_size), GFP_KERNEL);
- if (inst == NULL) {
- refcount_set(&rp->rph->ref, i);
- free_rp_inst(rp);
- return -ENOMEM;
- }
- inst->rph = rp->rph;
- freelist_add(&inst->freelist, &rp->freelist);
+ if (objpool_init(&rp->rph->pool, rp->maxactive, rp->data_size +
+ sizeof(struct kretprobe_instance), GFP_KERNEL,
+ rp->rph, kretprobe_init_inst, kretprobe_fini_pool)) {
+ kfree(rp->rph);
+ rp->rph = NULL;
+ return -ENOMEM;
}
- refcount_set(&rp->rph->ref, i);
-
+ rp->rph->rp = rp;
rp->nmissed = 0;
/* Establish function entry probe point */
ret = register_kprobe(&rp->kp);
diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index 3b21f4063258..f5bf98e6b2ac 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -187,7 +187,7 @@ static void fprobe_init(struct fprobe *fp)
static int fprobe_init_rethook(struct fprobe *fp, int num)
{
- int i, size;
+ int size;
if (num <= 0)
return -EINVAL;
@@ -202,26 +202,18 @@ static int fprobe_init_rethook(struct fprobe *fp, int num)
if (size <= 0)
return -EINVAL;
- fp->rethook = rethook_alloc((void *)fp, fprobe_exit_handler);
- if (!fp->rethook)
- return -ENOMEM;
- for (i = 0; i < size; i++) {
- struct fprobe_rethook_node *node;
-
- node = kzalloc(sizeof(*node) + fp->entry_data_size, GFP_KERNEL);
- if (!node) {
- rethook_free(fp->rethook);
- fp->rethook = NULL;
- return -ENOMEM;
- }
- rethook_add_node(fp->rethook, &node->node);
- }
+ /* Initialize rethook */
+ fp->rethook = rethook_alloc((void *)fp, fprobe_exit_handler,
+ sizeof(struct fprobe_rethook_node), size);
+ if (IS_ERR(fp->rethook))
+ return PTR_ERR(fp->rethook);
+
return 0;
}
static void fprobe_fail_cleanup(struct fprobe *fp)
{
- if (fp->rethook) {
+ if (!IS_ERR_OR_NULL(fp->rethook)) {
/* Don't need to cleanup rethook->handler because this is not used. */
rethook_free(fp->rethook);
fp->rethook = NULL;
@@ -379,14 +371,14 @@ int unregister_fprobe(struct fprobe *fp)
if (!fprobe_is_registered(fp))
return -EINVAL;
- if (fp->rethook)
+ if (!IS_ERR_OR_NULL(fp->rethook))
rethook_stop(fp->rethook);
ret = unregister_ftrace_function(&fp->ops);
if (ret < 0)
return ret;
- if (fp->rethook)
+ if (!IS_ERR_OR_NULL(fp->rethook))
rethook_free(fp->rethook);
ftrace_free_filter(&fp->ops);
diff --git a/kernel/trace/rethook.c b/kernel/trace/rethook.c
index 5eb9b598f4e9..13c8e6773892 100644
--- a/kernel/trace/rethook.c
+++ b/kernel/trace/rethook.c
@@ -9,6 +9,7 @@
#include <linux/rethook.h>
#include <linux/slab.h>
#include <linux/sort.h>
+#include <linux/smp.h>
/* Return hook list (shadow stack by list) */
@@ -36,21 +37,7 @@ void rethook_flush_task(struct task_struct *tk)
static void rethook_free_rcu(struct rcu_head *head)
{
struct rethook *rh = container_of(head, struct rethook, rcu);
- struct rethook_node *rhn;
- struct freelist_node *node;
- int count = 1;
-
- node = rh->pool.head;
- while (node) {
- rhn = container_of(node, struct rethook_node, freelist);
- node = node->next;
- kfree(rhn);
- count++;
- }
-
- /* The rh->ref is the number of pooled node + 1 */
- if (refcount_sub_and_test(count, &rh->ref))
- kfree(rh);
+ objpool_fini(&rh->pool);
}
/**
@@ -83,54 +70,62 @@ void rethook_free(struct rethook *rh)
call_rcu(&rh->rcu, rethook_free_rcu);
}
+static int rethook_init_node(void *nod, void *context)
+{
+ struct rethook_node *node = nod;
+
+ node->rethook = context;
+ return 0;
+}
+
+static int rethook_fini_pool(struct objpool_head *head, void *context)
+{
+ kfree(context);
+ return 0;
+}
+
/**
* rethook_alloc() - Allocate struct rethook.
* @data: a data to pass the @handler when hooking the return.
- * @handler: the return hook callback function.
+ * @handler: the return hook callback function, must NOT be NULL
+ * @size: node size: rethook node and additional data
+ * @num: number of rethook nodes to be preallocated
*
* Allocate and initialize a new rethook with @data and @handler.
- * Return NULL if memory allocation fails or @handler is NULL.
+ * Return pointer of new rethook, or error codes for failures.
+ *
* Note that @handler == NULL means this rethook is going to be freed.
*/
-struct rethook *rethook_alloc(void *data, rethook_handler_t handler)
+struct rethook *rethook_alloc(void *data, rethook_handler_t handler,
+ int size, int num)
{
- struct rethook *rh = kzalloc(sizeof(struct rethook), GFP_KERNEL);
+ struct rethook *rh;
- if (!rh || !handler) {
- kfree(rh);
- return NULL;
- }
+ if (!handler || num <= 0 || size < sizeof(struct rethook_node))
+ return ERR_PTR(-EINVAL);
+
+ rh = kzalloc(sizeof(struct rethook), GFP_KERNEL);
+ if (!rh)
+ return ERR_PTR(-ENOMEM);
rh->data = data;
rh->handler = handler;
- rh->pool.head = NULL;
- refcount_set(&rh->ref, 1);
+ /* initialize the objpool for rethook nodes */
+ if (objpool_init(&rh->pool, num, size, GFP_KERNEL, rh,
+ rethook_init_node, rethook_fini_pool)) {
+ kfree(rh);
+ return ERR_PTR(-ENOMEM);
+ }
return rh;
}
-/**
- * rethook_add_node() - Add a new node to the rethook.
- * @rh: the struct rethook.
- * @node: the struct rethook_node to be added.
- *
- * Add @node to @rh. User must allocate @node (as a part of user's
- * data structure.) The @node fields are initialized in this function.
- */
-void rethook_add_node(struct rethook *rh, struct rethook_node *node)
-{
- node->rethook = rh;
- freelist_add(&node->freelist, &rh->pool);
- refcount_inc(&rh->ref);
-}
-
static void free_rethook_node_rcu(struct rcu_head *head)
{
struct rethook_node *node = container_of(head, struct rethook_node, rcu);
+ struct rethook *rh = node->rethook;
- if (refcount_dec_and_test(&node->rethook->ref))
- kfree(node->rethook);
- kfree(node);
+ objpool_drop(node, &rh->pool);
}
/**
@@ -145,7 +140,7 @@ void rethook_recycle(struct rethook_node *node)
lockdep_assert_preemption_disabled();
if (likely(READ_ONCE(node->rethook->handler)))
- freelist_add(&node->freelist, &node->rethook->pool);
+ objpool_push(node, &node->rethook->pool);
else
call_rcu(&node->rcu, free_rethook_node_rcu);
}
@@ -161,7 +156,6 @@ NOKPROBE_SYMBOL(rethook_recycle);
struct rethook_node *rethook_try_get(struct rethook *rh)
{
rethook_handler_t handler = READ_ONCE(rh->handler);
- struct freelist_node *fn;
lockdep_assert_preemption_disabled();
@@ -178,11 +172,7 @@ struct rethook_node *rethook_try_get(struct rethook *rh)
if (unlikely(!rcu_is_watching()))
return NULL;
- fn = freelist_try_get(&rh->pool);
- if (!fn)
- return NULL;
-
- return container_of(fn, struct rethook_node, freelist);
+ return (struct rethook_node *)objpool_pop(&rh->pool);
}
NOKPROBE_SYMBOL(rethook_try_get);
--
2.40.1
The test_objpool module (test_objpool) will run several testcases
for objpool stress and performance evaluation. Each testcase will
have all available cpu cores involved to create a situation of high
parallel and high contention.
As of now there are 5 groups and 5 * 2 testcases in total:
1) group 1: synchronous mode
objpool is managed synchronously, that is, all objects are to be
reclaimed before objpool finalization and the objpool owner makes
sure of it. All threads on different cores run in the same pace
2) group 2: synchronous mode + hrtimer
this case have 2 customers: normal threads and hrtimer softirqs
3) group 3: synchronous + overrun mode
This test group is mainly for performance evaluation of missing
cases when pre-allocated objects are less than the requested
4) group 4: asynchronous mode
This case is just an emulation of kretprobe, with refcount used
to control the objpool lifecycle
5) group 5: asynchronous mode with hrtimer
hrtimer softirq is introduced to stress async objpool operations
Signed-off-by: wuqiang.matt <[email protected]>
---
lib/Kconfig.debug | 11 +
lib/Makefile | 2 +
lib/test_objpool.c | 689 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 702 insertions(+)
create mode 100644 lib/test_objpool.c
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index d6798513a8c2..6598604cf6c8 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2931,6 +2931,17 @@ config TEST_CLOCKSOURCE_WATCHDOG
If unsure, say N.
+config TEST_OBJPOOL
+ tristate "Test module for correctness and stress of objpool"
+ default n
+ depends on m && DEBUG_KERNEL
+ help
+ This builds the "test_objpool" module that should be used for
+ correctness verification and concurrent testings of objects
+ allocation and reclamation.
+
+ If unsure, say N.
+
endif # RUNTIME_TESTING_MENU
config ARCH_USE_MEMTEST
diff --git a/lib/Makefile b/lib/Makefile
index 7a84c922d9ff..19b936f2af1c 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -106,6 +106,8 @@ obj-$(CONFIG_KPROBES_SANITY_TEST) += test_kprobes.o
obj-$(CONFIG_TEST_REF_TRACKER) += test_ref_tracker.o
CFLAGS_test_fprobe.o += $(CC_FLAGS_FTRACE)
obj-$(CONFIG_FPROBE_SANITY_TEST) += test_fprobe.o
+obj-$(CONFIG_TEST_OBJPOOL) += test_objpool.o
+
#
# CFLAGS for compiling floating point code inside the kernel. x86/Makefile turns
# off the generation of FPU/SSE* instructions for kernel proper but FPU_FLAGS
diff --git a/lib/test_objpool.c b/lib/test_objpool.c
new file mode 100644
index 000000000000..d329472f8ab6
--- /dev/null
+++ b/lib/test_objpool.c
@@ -0,0 +1,696 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Test module for lockless object pool
+ *
+ * Copyright: [email protected]
+ */
+
+#include <linux/version.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/sched.h>
+#include <linux/cpumask.h>
+#include <linux/completion.h>
+#include <linux/kthread.h>
+#include <linux/cpu.h>
+#include <linux/cpuset.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/delay.h>
+#include <linux/hrtimer.h>
+#include <linux/interrupt.h>
+#include <linux/objpool.h>
+
+#define OT_NR_MAX_BULK (16)
+
+/* memory usage */
+struct ot_mem_stat {
+ atomic_long_t alloc;
+ atomic_long_t free;
+};
+
+/* object allocation results */
+struct ot_obj_stat {
+ unsigned long nhits;
+ unsigned long nmiss;
+};
+
+/* control & results per testcase */
+struct ot_data {
+ struct rw_semaphore start;
+ struct completion wait;
+ struct completion rcu;
+ atomic_t nthreads ____cacheline_aligned_in_smp;
+ atomic_t stop ____cacheline_aligned_in_smp;
+ struct ot_mem_stat kmalloc;
+ struct ot_mem_stat vmalloc;
+ struct ot_obj_stat objects;
+ u64 duration;
+};
+
+/* testcase */
+struct ot_test {
+ int async; /* synchronous or asynchronous */
+ int mode; /* only mode 0 supported */
+ int objsz; /* object size */
+ int duration; /* ms */
+ int delay; /* ms */
+ int bulk_normal;
+ int bulk_irq;
+ unsigned long hrtimer; /* ms */
+ const char *name;
+ struct ot_data data;
+};
+
+/* per-cpu worker */
+struct ot_item {
+ struct objpool_head *pool; /* pool head */
+ struct ot_test *test; /* test parameters */
+
+ void (*worker)(struct ot_item *item, int irq);
+
+ /* hrtimer control */
+ ktime_t hrtcycle;
+ struct hrtimer hrtimer;
+
+ int bulk[2]; /* for thread and irq */
+ int delay;
+ u32 niters;
+
+ /* summary per thread */
+ struct ot_obj_stat stat[2]; /* thread and irq */
+ u64 duration;
+};
+
+/*
+ * memory leakage checking
+ */
+
+static void *ot_kzalloc(struct ot_test *test, long size)
+{
+ void *ptr = kzalloc(size, GFP_KERNEL);
+
+ if (ptr)
+ atomic_long_add(size, &test->data.kmalloc.alloc);
+ return ptr;
+}
+
+static void ot_kfree(struct ot_test *test, void *ptr, long size)
+{
+ if (!ptr)
+ return;
+ atomic_long_add(size, &test->data.kmalloc.free);
+ kfree(ptr);
+}
+
+static void ot_mem_report(struct ot_test *test)
+{
+ long alloc, free;
+
+ pr_info("memory allocation summary for %s\n", test->name);
+
+ alloc = atomic_long_read(&test->data.kmalloc.alloc);
+ free = atomic_long_read(&test->data.kmalloc.free);
+ pr_info(" kmalloc: %lu - %lu = %lu\n", alloc, free, alloc - free);
+
+ alloc = atomic_long_read(&test->data.vmalloc.alloc);
+ free = atomic_long_read(&test->data.vmalloc.free);
+ pr_info(" vmalloc: %lu - %lu = %lu\n", alloc, free, alloc - free);
+}
+
+/* user object instance */
+struct ot_node {
+ void *owner;
+ unsigned long data;
+ unsigned long refs;
+ unsigned long payload[32];
+};
+
+/* user objpool manager */
+struct ot_context {
+ struct objpool_head pool; /* objpool head */
+ struct ot_test *test; /* test parameters */
+ void *ptr; /* user pool buffer */
+ unsigned long size; /* buffer size */
+ struct rcu_head rcu;
+};
+
+static DEFINE_PER_CPU(struct ot_item, ot_pcup_items);
+
+static int ot_init_data(struct ot_data *data)
+{
+ memset(data, 0, sizeof(*data));
+ init_rwsem(&data->start);
+ init_completion(&data->wait);
+ init_completion(&data->rcu);
+ atomic_set(&data->nthreads, 1);
+
+ return 0;
+}
+
+static int ot_init_node(void *nod, void *context)
+{
+ struct ot_context *sop = context;
+ struct ot_node *on = nod;
+
+ on->owner = &sop->pool;
+ return 0;
+}
+
+static enum hrtimer_restart ot_hrtimer_handler(struct hrtimer *hrt)
+{
+ struct ot_item *item = container_of(hrt, struct ot_item, hrtimer);
+ struct ot_test *test = item->test;
+
+ if (atomic_read_acquire(&test->data.stop))
+ return HRTIMER_NORESTART;
+
+ /* do bulk-testings for objects pop/push */
+ item->worker(item, 1);
+
+ hrtimer_forward(hrt, hrt->base->get_time(), item->hrtcycle);
+ return HRTIMER_RESTART;
+}
+
+static void ot_start_hrtimer(struct ot_item *item)
+{
+ if (!item->test->hrtimer)
+ return;
+ hrtimer_start(&item->hrtimer, item->hrtcycle, HRTIMER_MODE_REL);
+}
+
+static void ot_stop_hrtimer(struct ot_item *item)
+{
+ if (!item->test->hrtimer)
+ return;
+ hrtimer_cancel(&item->hrtimer);
+}
+
+static int ot_init_hrtimer(struct ot_item *item, unsigned long hrtimer)
+{
+ struct hrtimer *hrt = &item->hrtimer;
+
+ if (!hrtimer)
+ return -ENOENT;
+
+ item->hrtcycle = ktime_set(0, hrtimer * 1000000UL);
+ hrtimer_init(hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ hrt->function = ot_hrtimer_handler;
+ return 0;
+}
+
+static int ot_init_cpu_item(struct ot_item *item,
+ struct ot_test *test,
+ struct objpool_head *pool,
+ void (*worker)(struct ot_item *, int))
+{
+ memset(item, 0, sizeof(*item));
+ item->pool = pool;
+ item->test = test;
+ item->worker = worker;
+
+ item->bulk[0] = test->bulk_normal;
+ item->bulk[1] = test->bulk_irq;
+ item->delay = test->delay;
+
+ /* initialize hrtimer */
+ ot_init_hrtimer(item, item->test->hrtimer);
+ return 0;
+}
+
+static int ot_thread_worker(void *arg)
+{
+ struct ot_item *item = arg;
+ struct ot_test *test = item->test;
+ ktime_t start;
+
+ atomic_inc(&test->data.nthreads);
+ down_read(&test->data.start);
+ up_read(&test->data.start);
+ start = ktime_get();
+ ot_start_hrtimer(item);
+ do {
+ if (atomic_read_acquire(&test->data.stop))
+ break;
+ /* do bulk-testings for objects pop/push */
+ item->worker(item, 0);
+ } while (!kthread_should_stop());
+ ot_stop_hrtimer(item);
+ item->duration = (u64) ktime_us_delta(ktime_get(), start);
+ if (atomic_dec_and_test(&test->data.nthreads))
+ complete(&test->data.wait);
+
+ return 0;
+}
+
+static void ot_perf_report(struct ot_test *test, u64 duration)
+{
+ struct ot_obj_stat total, normal = {0}, irq = {0};
+ int cpu, nthreads = 0;
+
+ pr_info("\n");
+ pr_info("Testing summary for %s\n", test->name);
+
+ for_each_possible_cpu(cpu) {
+ struct ot_item *item = per_cpu_ptr(&ot_pcup_items, cpu);
+ if (!item->duration)
+ continue;
+ normal.nhits += item->stat[0].nhits;
+ normal.nmiss += item->stat[0].nmiss;
+ irq.nhits += item->stat[1].nhits;
+ irq.nmiss += item->stat[1].nmiss;
+ pr_info("CPU: %d duration: %lluus\n", cpu, item->duration);
+ pr_info("\tthread:\t%16lu hits \t%16lu miss\n",
+ item->stat[0].nhits, item->stat[0].nmiss);
+ pr_info("\tirq: \t%16lu hits \t%16lu miss\n",
+ item->stat[1].nhits, item->stat[1].nmiss);
+ pr_info("\ttotal: \t%16lu hits \t%16lu miss\n",
+ item->stat[0].nhits + item->stat[1].nhits,
+ item->stat[0].nmiss + item->stat[1].nmiss);
+ nthreads++;
+ }
+
+ total.nhits = normal.nhits + irq.nhits;
+ total.nmiss = normal.nmiss + irq.nmiss;
+
+ pr_info("ALL: \tnthreads: %d duration: %lluus\n", nthreads, duration);
+ pr_info("SUM: \t%16lu hits \t%16lu miss\n",
+ total.nhits, total.nmiss);
+
+ test->data.objects = total;
+ test->data.duration = duration;
+}
+
+/*
+ * synchronous test cases for objpool manipulation
+ */
+
+/* objpool manipulation for synchronous mode (percpu objpool) */
+static struct ot_context *ot_init_sync_m0(struct ot_test *test)
+{
+ struct ot_context *sop = NULL;
+ int max = num_possible_cpus() << 3;
+ gfp_t gfp = GFP_KERNEL;
+
+ sop = (struct ot_context *)ot_kzalloc(test, sizeof(*sop));
+ if (!sop)
+ return NULL;
+ sop->test = test;
+ if (test->objsz < 512)
+ gfp = GFP_ATOMIC;
+
+ if (objpool_init(&sop->pool, max, test->objsz,
+ gfp, sop, ot_init_node, NULL)) {
+ ot_kfree(test, sop, sizeof(*sop));
+ return NULL;
+ }
+ WARN_ON(max != sop->pool.nr_objs);
+
+ return sop;
+}
+
+static void ot_fini_sync(struct ot_context *sop)
+{
+ objpool_fini(&sop->pool);
+ ot_kfree(sop->test, sop, sizeof(*sop));
+}
+
+struct {
+ struct ot_context * (*init)(struct ot_test *oc);
+ void (*fini)(struct ot_context *sop);
+} g_ot_sync_ops[] = {
+ {.init = ot_init_sync_m0, .fini = ot_fini_sync},
+};
+
+/*
+ * synchronous test cases: performance mode
+ */
+
+static void ot_bulk_sync(struct ot_item *item, int irq)
+{
+ struct ot_node *nods[OT_NR_MAX_BULK];
+ int i;
+
+ for (i = 0; i < item->bulk[irq]; i++)
+ nods[i] = objpool_pop(item->pool);
+
+ if (!irq && (item->delay || !(++(item->niters) & 0x7FFF)))
+ msleep(item->delay);
+
+ while (i-- > 0) {
+ struct ot_node *on = nods[i];
+ if (on) {
+ on->refs++;
+ objpool_push(on, item->pool);
+ item->stat[irq].nhits++;
+ } else {
+ item->stat[irq].nmiss++;
+ }
+ }
+}
+
+static int ot_start_sync(struct ot_test *test)
+{
+ struct ot_context *sop;
+ ktime_t start;
+ u64 duration;
+ unsigned long timeout;
+ int cpu;
+
+ /* initialize objpool for syncrhonous testcase */
+ sop = g_ot_sync_ops[test->mode].init(test);
+ if (!sop)
+ return -ENOMEM;
+
+ /* grab rwsem to block testing threads */
+ down_write(&test->data.start);
+
+ for_each_possible_cpu(cpu) {
+ struct ot_item *item = per_cpu_ptr(&ot_pcup_items, cpu);
+ struct task_struct *work;
+
+ ot_init_cpu_item(item, test, &sop->pool, ot_bulk_sync);
+
+ /* skip offline cpus */
+ if (!cpu_online(cpu))
+ continue;
+
+ work = kthread_create_on_node(ot_thread_worker, item,
+ cpu_to_node(cpu), "ot_worker_%d", cpu);
+ if (IS_ERR(work)) {
+ pr_err("failed to create thread for cpu %d\n", cpu);
+ } else {
+ kthread_bind(work, cpu);
+ wake_up_process(work);
+ }
+ }
+
+ /* wait a while to make sure all threads waiting at start line */
+ msleep(20);
+
+ /* in case no threads were created: memory insufficient ? */
+ if (atomic_dec_and_test(&test->data.nthreads))
+ complete(&test->data.wait);
+
+ // sched_set_fifo_low(current);
+
+ /* start objpool testing threads */
+ start = ktime_get();
+ up_write(&test->data.start);
+
+ /* yeild cpu to worker threads for duration ms */
+ timeout = msecs_to_jiffies(test->duration);
+ schedule_timeout_interruptible(timeout);
+
+ /* tell workers threads to quit */
+ atomic_set_release(&test->data.stop, 1);
+
+ /* wait all workers threads finish and quit */
+ wait_for_completion(&test->data.wait);
+ duration = (u64) ktime_us_delta(ktime_get(), start);
+
+ /* cleanup objpool */
+ g_ot_sync_ops[test->mode].fini(sop);
+
+ /* report testing summary and performance results */
+ ot_perf_report(test, duration);
+
+ /* report memory allocation summary */
+ ot_mem_report(test);
+
+ return 0;
+}
+
+/*
+ * asynchronous test cases: pool lifecycle controlled by refcount
+ */
+
+static void ot_fini_async_rcu(struct rcu_head *rcu)
+{
+ struct ot_context *sop = container_of(rcu, struct ot_context, rcu);
+ struct ot_test *test = sop->test;
+
+ /* here all cpus are aware of the stop event: test->data.stop = 1 */
+ WARN_ON(!atomic_read_acquire(&test->data.stop));
+
+ objpool_fini(&sop->pool);
+ complete(&test->data.rcu);
+}
+
+static void ot_fini_async(struct ot_context *sop)
+{
+ /* make sure the stop event is acknowledged by all cores */
+ call_rcu(&sop->rcu, ot_fini_async_rcu);
+}
+
+static int ot_objpool_release(struct objpool_head *head, void *context)
+{
+ struct ot_context *sop = context;
+
+ WARN_ON(!head || !sop || head != &sop->pool);
+
+ /* do context cleaning if needed */
+ if (sop)
+ ot_kfree(sop->test, sop, sizeof(*sop));
+
+ return 0;
+}
+
+static struct ot_context *ot_init_async_m0(struct ot_test *test)
+{
+ struct ot_context *sop = NULL;
+ int max = num_possible_cpus() << 3;
+ gfp_t gfp = GFP_KERNEL;
+
+ sop = (struct ot_context *)ot_kzalloc(test, sizeof(*sop));
+ if (!sop)
+ return NULL;
+ sop->test = test;
+ if (test->objsz < 512)
+ gfp = GFP_ATOMIC;
+
+ if (objpool_init(&sop->pool, max, test->objsz, gfp, sop,
+ ot_init_node, ot_objpool_release)) {
+ ot_kfree(test, sop, sizeof(*sop));
+ return NULL;
+ }
+ WARN_ON(max != sop->pool.nr_objs);
+
+ return sop;
+}
+
+struct {
+ struct ot_context * (*init)(struct ot_test *oc);
+ void (*fini)(struct ot_context *sop);
+} g_ot_async_ops[] = {
+ {.init = ot_init_async_m0, .fini = ot_fini_async},
+};
+
+static void ot_nod_recycle(struct ot_node *on, struct objpool_head *pool,
+ int release)
+{
+ struct ot_context *sop;
+
+ on->refs++;
+
+ if (!release) {
+ /* push object back to opjpool for reuse */
+ objpool_push(on, pool);
+ return;
+ }
+
+ sop = container_of(pool, struct ot_context, pool);
+ WARN_ON(sop != pool->context);
+
+ /* unref objpool with nod removed forever */
+ objpool_drop(on, pool);
+}
+
+static void ot_bulk_async(struct ot_item *item, int irq)
+{
+ struct ot_test *test = item->test;
+ struct ot_node *nods[OT_NR_MAX_BULK];
+ int i, stop;
+
+ for (i = 0; i < item->bulk[irq]; i++)
+ nods[i] = objpool_pop(item->pool);
+
+ if (!irq) {
+ if (item->delay || !(++(item->niters) & 0x7FFF))
+ msleep(item->delay);
+ get_cpu();
+ }
+
+ stop = atomic_read_acquire(&test->data.stop);
+
+ /* drop all objects and deref objpool */
+ while (i-- > 0) {
+ struct ot_node *on = nods[i];
+
+ if (on) {
+ on->refs++;
+ ot_nod_recycle(on, item->pool, stop);
+ item->stat[irq].nhits++;
+ } else {
+ item->stat[irq].nmiss++;
+ }
+ }
+
+ if (!irq)
+ put_cpu();
+}
+
+static int ot_start_async(struct ot_test *test)
+{
+ struct ot_context *sop;
+ ktime_t start;
+ u64 duration;
+ unsigned long timeout;
+ int cpu;
+
+ /* initialize objpool for syncrhonous testcase */
+ sop = g_ot_async_ops[test->mode].init(test);
+ if (!sop)
+ return -ENOMEM;
+
+ /* grab rwsem to block testing threads */
+ down_write(&test->data.start);
+
+ for_each_possible_cpu(cpu) {
+ struct ot_item *item = per_cpu_ptr(&ot_pcup_items, cpu);
+ struct task_struct *work;
+
+ ot_init_cpu_item(item, test, &sop->pool, ot_bulk_async);
+
+ /* skip offline cpus */
+ if (!cpu_online(cpu))
+ continue;
+
+ work = kthread_create_on_node(ot_thread_worker, item,
+ cpu_to_node(cpu), "ot_worker_%d", cpu);
+ if (IS_ERR(work)) {
+ pr_err("failed to create thread for cpu %d\n", cpu);
+ } else {
+ kthread_bind(work, cpu);
+ wake_up_process(work);
+ }
+ }
+
+ /* wait a while to make sure all threads waiting at start line */
+ msleep(20);
+
+ /* in case no threads were created: memory insufficient ? */
+ if (atomic_dec_and_test(&test->data.nthreads))
+ complete(&test->data.wait);
+
+ /* start objpool testing threads */
+ start = ktime_get();
+ up_write(&test->data.start);
+
+ /* yeild cpu to worker threads for duration ms */
+ timeout = msecs_to_jiffies(test->duration);
+ schedule_timeout_interruptible(timeout);
+
+ /* tell workers threads to quit */
+ atomic_set_release(&test->data.stop, 1);
+
+ /* do async-finalization */
+ g_ot_async_ops[test->mode].fini(sop);
+
+ /* wait all workers threads finish and quit */
+ wait_for_completion(&test->data.wait);
+ duration = (u64) ktime_us_delta(ktime_get(), start);
+
+ /* assure rcu callback is triggered */
+ wait_for_completion(&test->data.rcu);
+
+ /*
+ * now we are sure that objpool is finalized either
+ * by rcu callback or by worker threads
+ */
+
+ /* report testing summary and performance results */
+ ot_perf_report(test, duration);
+
+ /* report memory allocation summary */
+ ot_mem_report(test);
+
+ return 0;
+}
+
+/*
+ * predefined testing cases:
+ * synchronous case / overrun case / async case
+ *
+ * async: synchronous or asynchronous testing
+ * mode: only mode 0 supported
+ * objsz: object size
+ * duration: int, total test time in ms
+ * delay: int, delay (in ms) between each iteration
+ * bulk_normal: int, repeat times for thread worker
+ * bulk_irq: int, repeat times for irq consumer
+ * hrtimer: unsigned long, hrtimer intervnal in ms
+ * name: char *, tag for current test ot_item
+ */
+
+#define NODE_COMPACT sizeof(struct ot_node)
+#define NODE_VMALLOC (512)
+
+struct ot_test g_testcases[] = {
+
+ /* sync & normal */
+ {0, 0, NODE_COMPACT, 1000, 0, 1, 0, 0, "sync: percpu objpool"},
+ {0, 0, NODE_VMALLOC, 1000, 0, 1, 0, 0, "sync: percpu objpool from vmalloc"},
+
+ /* sync & hrtimer */
+ {0, 0, NODE_COMPACT, 1000, 0, 1, 1, 4, "sync & hrtimer: percpu objpool"},
+ {0, 0, NODE_VMALLOC, 1000, 0, 1, 1, 4, "sync & hrtimer: percpu objpool from vmalloc"},
+
+ /* sync & overrun */
+ {0, 0, NODE_COMPACT, 1000, 0, 16, 0, 0, "sync overrun: percpu objpool"},
+ {0, 0, NODE_VMALLOC, 1000, 0, 16, 0, 0, "sync overrun: percpu objpool from vmalloc"},
+
+ /* async mode */
+ {1, 0, NODE_COMPACT, 1000, 100, 1, 0, 0, "async: percpu objpool"},
+ {1, 0, NODE_VMALLOC, 1000, 100, 1, 0, 0, "async: percpu objpool from vmalloc"},
+
+ /* async + hrtimer mode */
+ {1, 0, NODE_COMPACT, 1000, 0, 4, 4, 4, "async & hrtimer: percpu objpool"},
+ {1, 0, NODE_VMALLOC, 1000, 0, 4, 4, 4, "async & hrtimer: percpu objpool from vmalloc"},
+};
+
+static int __init ot_mod_init(void)
+{
+ int i;
+
+ /* perform testings */
+ for (i = 0; i < ARRAY_SIZE(g_testcases); i++) {
+ ot_init_data(&g_testcases[i].data);
+ if (g_testcases[i].async)
+ ot_start_async(&g_testcases[i]);
+ else
+ ot_start_sync(&g_testcases[i]);
+ }
+
+ /* show tests summary */
+ pr_info("\n");
+ pr_info("Summary of testcases:\n");
+ for (i = 0; i < ARRAY_SIZE(g_testcases); i++) {
+ pr_info(" duration: %lluus \thits: %10lu \tmiss: %10lu \t%s\n",
+ g_testcases[i].data.duration, g_testcases[i].data.objects.nhits,
+ g_testcases[i].data.objects.nmiss, g_testcases[i].name);
+ }
+
+ return -EAGAIN;
+}
+
+static void __exit ot_mod_exit(void)
+{
+}
+
+module_init(ot_mod_init);
+module_exit(ot_mod_exit);
+
+MODULE_LICENSE("GPL");
\ No newline at end of file
--
2.40.1
This patch will remove freelist.h from kernel source tree, since the
only use cases (kretprobe and rethook) are converted to objpool.
Signed-off-by: wuqiang.matt <[email protected]>
---
include/linux/freelist.h | 129 ---------------------------------------
1 file changed, 129 deletions(-)
delete mode 100644 include/linux/freelist.h
diff --git a/include/linux/freelist.h b/include/linux/freelist.h
deleted file mode 100644
index fc1842b96469..000000000000
--- a/include/linux/freelist.h
+++ /dev/null
@@ -1,129 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause */
-#ifndef FREELIST_H
-#define FREELIST_H
-
-#include <linux/atomic.h>
-
-/*
- * Copyright: [email protected]
- *
- * A simple CAS-based lock-free free list. Not the fastest thing in the world
- * under heavy contention, but simple and correct (assuming nodes are never
- * freed until after the free list is destroyed), and fairly speedy under low
- * contention.
- *
- * Adapted from: https://moodycamel.com/blog/2014/solving-the-aba-problem-for-lock-free-free-lists
- */
-
-struct freelist_node {
- atomic_t refs;
- struct freelist_node *next;
-};
-
-struct freelist_head {
- struct freelist_node *head;
-};
-
-#define REFS_ON_FREELIST 0x80000000
-#define REFS_MASK 0x7FFFFFFF
-
-static inline void __freelist_add(struct freelist_node *node, struct freelist_head *list)
-{
- /*
- * Since the refcount is zero, and nobody can increase it once it's
- * zero (except us, and we run only one copy of this method per node at
- * a time, i.e. the single thread case), then we know we can safely
- * change the next pointer of the node; however, once the refcount is
- * back above zero, then other threads could increase it (happens under
- * heavy contention, when the refcount goes to zero in between a load
- * and a refcount increment of a node in try_get, then back up to
- * something non-zero, then the refcount increment is done by the other
- * thread) -- so if the CAS to add the node to the actual list fails,
- * decrese the refcount and leave the add operation to the next thread
- * who puts the refcount back to zero (which could be us, hence the
- * loop).
- */
- struct freelist_node *head = READ_ONCE(list->head);
-
- for (;;) {
- WRITE_ONCE(node->next, head);
- atomic_set_release(&node->refs, 1);
-
- if (!try_cmpxchg_release(&list->head, &head, node)) {
- /*
- * Hmm, the add failed, but we can only try again when
- * the refcount goes back to zero.
- */
- if (atomic_fetch_add_release(REFS_ON_FREELIST - 1, &node->refs) == 1)
- continue;
- }
- return;
- }
-}
-
-static inline void freelist_add(struct freelist_node *node, struct freelist_head *list)
-{
- /*
- * We know that the should-be-on-freelist bit is 0 at this point, so
- * it's safe to set it using a fetch_add.
- */
- if (!atomic_fetch_add_release(REFS_ON_FREELIST, &node->refs)) {
- /*
- * Oh look! We were the last ones referencing this node, and we
- * know we want to add it to the free list, so let's do it!
- */
- __freelist_add(node, list);
- }
-}
-
-static inline struct freelist_node *freelist_try_get(struct freelist_head *list)
-{
- struct freelist_node *prev, *next, *head = smp_load_acquire(&list->head);
- unsigned int refs;
-
- while (head) {
- prev = head;
- refs = atomic_read(&head->refs);
- if ((refs & REFS_MASK) == 0 ||
- !atomic_try_cmpxchg_acquire(&head->refs, &refs, refs+1)) {
- head = smp_load_acquire(&list->head);
- continue;
- }
-
- /*
- * Good, reference count has been incremented (it wasn't at
- * zero), which means we can read the next and not worry about
- * it changing between now and the time we do the CAS.
- */
- next = READ_ONCE(head->next);
- if (try_cmpxchg_acquire(&list->head, &head, next)) {
- /*
- * Yay, got the node. This means it was on the list,
- * which means should-be-on-freelist must be false no
- * matter the refcount (because nobody else knows it's
- * been taken off yet, it can't have been put back on).
- */
- WARN_ON_ONCE(atomic_read(&head->refs) & REFS_ON_FREELIST);
-
- /*
- * Decrease refcount twice, once for our ref, and once
- * for the list's ref.
- */
- atomic_fetch_add(-2, &head->refs);
-
- return head;
- }
-
- /*
- * OK, the head must have changed on us, but we still need to decrement
- * the refcount we increased.
- */
- refs = atomic_fetch_add(-1, &prev->refs);
- if (refs == REFS_ON_FREELIST + 1)
- __freelist_add(prev, list);
- }
-
- return NULL;
-}
-
-#endif /* FREELIST_H */
--
2.40.1
objpool, a scalable and lockless ring-array based object pool, was
introduced to replace the original freelist (a LIFO queue based on
singly linked list) to improve kretprobe scalability.
Signed-off-by: wuqiang.matt <[email protected]>
---
MAINTAINERS | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index 48abe1a281f2..1c0a38d763a2 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15328,6 +15328,13 @@ F: include/linux/objagg.h
F: lib/objagg.c
F: lib/test_objagg.c
+OBJPOOL
+M: Matt Wu <[email protected]>
+S: Supported
+F: include/linux/objpool.h
+F: lib/objpool.c
+F: lib/test_objpool.c
+
OBJTOOL
M: Josh Poimboeuf <[email protected]>
M: Peter Zijlstra <[email protected]>
--
2.40.1
Hi,
On Tue, 17 Oct 2023 21:56:49 +0800
"wuqiang.matt" <[email protected]> wrote:
> This patch series introduces a scalable and lockless ring-array based
> object pool to improve scalability of kretprobed routines.
>
> v11:
> *) patchset rebased to branch probes/core of linux-trace.git
> *) objpool: objpool_fini optimized for better code readability
> *) test_objpool: asynchronous releasing of objpool now covered
>
> wuqiang.matt (5):
> lib: objpool added: ring-array based lockless MPMC
> lib: objpool test module added
> kprobes: kretprobe scalability improvement with objpool
> kprobes: freelist.h removed
> MAINTAINERS: objpool added
OK, this version looks good to me.
Acked-by: Masami Hiramatsu (Google) <[email protected]>
I'll pick this series on for-next branch.
Thank you,
>
> MAINTAINERS | 7 +
> include/linux/freelist.h | 129 --------
> include/linux/kprobes.h | 11 +-
> include/linux/objpool.h | 176 ++++++++++
> include/linux/rethook.h | 16 +-
> kernel/kprobes.c | 93 +++---
> kernel/trace/fprobe.c | 32 +-
> kernel/trace/rethook.c | 90 +++--
> lib/Kconfig.debug | 11 +
> lib/Makefile | 4 +-
> lib/objpool.c | 286 ++++++++++++++++
> lib/test_objpool.c | 689 +++++++++++++++++++++++++++++++++++++++
> 12 files changed, 1270 insertions(+), 274 deletions(-)
> delete mode 100644 include/linux/freelist.h
> create mode 100644 include/linux/objpool.h
> create mode 100644 lib/objpool.c
> create mode 100644 lib/test_objpool.c
>
> --
> 2.40.1
>
--
Masami Hiramatsu (Google) <[email protected]>