The five patches here change the following files :
Documentation/kernel-parameters.txt | 3 ++
drivers/oprofile/buffer_sync.c | 49 ++++++++++++++++++++++++++----------
drivers/oprofile/cpu_buffer.c | 6 +---
drivers/oprofile/event_buffer.h | 1
drivers/oprofile/oprof.c | 25 +++++++++++++-----
fs/dcookies.c | 6 ++++
6 files changed, 67 insertions(+), 23 deletions(-)
please apply
john
My previous fix was incomplete, we could get the same thing happening
on the init-failure path. Fix that.
diff -Naur -X dontdiff linux-cvs/drivers/oprofile/buffer_sync.c linux-me/drivers/oprofile/buffer_sync.c
--- linux-cvs/drivers/oprofile/buffer_sync.c 2003-05-26 03:20:20.000000000 +0100
+++ linux-me/drivers/oprofile/buffer_sync.c 2003-05-26 04:25:15.000000000 +0100
@@ -127,6 +127,14 @@
};
+static void end_sync_timer(void)
+{
+ del_timer_sync(&sync_timer);
+ /* timer might have queued work, make sure it's completed. */
+ flush_scheduled_work();
+}
+
+
int sync_start(void)
{
int err;
@@ -158,7 +166,7 @@
out2:
profile_event_unregister(EXIT_TASK, &exit_task_nb);
out1:
- del_timer_sync(&sync_timer);
+ end_sync_timer();
goto out;
}
@@ -169,9 +177,7 @@
profile_event_unregister(EXIT_TASK, &exit_task_nb);
profile_event_unregister(EXIT_MMAP, &exit_mmap_nb);
profile_event_unregister(EXEC_UNMAP, &exec_unmap_nb);
- del_timer_sync(&sync_timer);
- /* timer might have queued work, make sure it's completed. */
- flush_scheduled_work();
+ end_sync_timer();
}
The code that attempts to reset last_task and in_kernel has a race
against samples appearing during the handling of the buffers, that
causes a small number of mis-attribution of samples. Closing the
window is non-obvious, and not worth it, so we just make it smaller.
Even without the patch, there seem to be few such "bad" samples
because its effects are mitigated on a switch into userspace or
a task switch.
diff -Naur -X dontdiff linux-cvs/drivers/oprofile/buffer_sync.c linux-me/drivers/oprofile/buffer_sync.c
--- linux-cvs/drivers/oprofile/buffer_sync.c 2003-05-26 03:20:20.000000000 +0100
+++ linux-me/drivers/oprofile/buffer_sync.c 2003-05-26 04:25:15.000000000 +0100
@@ -366,12 +377,26 @@
}
-/* compute number of filled slots in cpu_buffer queue */
-static unsigned long nr_filled_slots(struct oprofile_cpu_buffer * b)
+/* "acquire" as many cpu buffer slots as we can */
+static unsigned long get_slots(struct oprofile_cpu_buffer * b)
{
unsigned long head = b->head_pos;
unsigned long tail = b->tail_pos;
+ /*
+ * Subtle. This resets the persistent last_task
+ * and in_kernel values used for switching notes.
+ * BUT, there is a small window between reading
+ * head_pos, and this call, that means samples
+ * can appear at the new head position, but not
+ * be prefixed with the notes for switching
+ * kernel mode or a task switch. This small hole
+ * can lead to mis-attribution or samples where
+ * we don't know if it's in the kernel or not,
+ * at the start of an event buffer.
+ */
+ cpu_buffer_reset(b);
+
if (head >= tail)
return head - tail;
@@ -408,9 +433,9 @@
/* Remember, only we can modify tail_pos */
- unsigned long const available_elements = nr_filled_slots(cpu_buf);
+ unsigned long const available = get_slots(cpu_buf);
- for (i=0; i < available_elements; ++i) {
+ for (i=0; i < available; ++i) {
struct op_sample * s = &cpu_buf->buffer[cpu_buf->tail_pos];
if (is_ctx_switch(s->eip)) {
@@ -435,8 +460,6 @@
increment_tail(cpu_buf);
}
release_mm(mm);
-
- cpu_buffer_reset(cpu_buf);
}
d_path() can return -ENAMETOOLONG these days. Pass it upstream.
diff -Naur -X dontdiff linux-cvs/fs/dcookies.c linux-me/fs/dcookies.c
--- linux-cvs/fs/dcookies.c 2003-05-19 19:57:28.000000000 +0100
+++ linux-me/fs/dcookies.c 2003-05-19 20:05:16.000000000 +0100
@@ -175,6 +175,11 @@
/* FIXME: (deleted) ? */
path = d_path(dcs->dentry, dcs->vfsmnt, kbuf, PAGE_SIZE);
+ if (IS_ERR(path)) {
+ err = PTR_ERR(path);
+ goto out_free;
+ }
+
err = -ERANGE;
pathlen = kbuf + PAGE_SIZE - path;
@@ -184,6 +189,7 @@
err = -EFAULT;
}
+out_free:
kfree(kbuf);
out:
up(&dcookie_sem);
Fix a stale comment.
diff -Naur -X dontdiff linux-cvs/drivers/oprofile/cpu_buffer.c linux-me/drivers/oprofile/cpu_buffer.c
--- linux-cvs/drivers/oprofile/cpu_buffer.c 2003-05-26 03:20:20.000000000 +0100
+++ linux-me/drivers/oprofile/cpu_buffer.c 2003-05-26 03:24:38.000000000 +0100
@@ -168,10 +168,8 @@
}
-/* resets the cpu buffer to a sane state - should be called with
- * cpu_buf->int_lock held
- */
-void cpu_buffer_reset(struct oprofile_cpu_buffer *cpu_buf)
+/* Resets the cpu buffer to a sane state. */
+void cpu_buffer_reset(struct oprofile_cpu_buffer * cpu_buf)
{
/* reset these to invalid values; the next sample
* collected will populate the buffer with proper
A patch mostly by Will Cohen, adding a parameter to OProfile to
over-ride use of the perfctr hardware. Useful for testing and
a host of other things.
diff -Naur -X dontdiff linux-cvs/Documentation/kernel-parameters.txt linux-me/Documentation/kernel-parameters.txt
--- linux-cvs/Documentation/kernel-parameters.txt 2003-03-30 21:12:29.000000000 +0100
+++ linux-me/Documentation/kernel-parameters.txt 2003-05-26 04:53:57.000000000 +0100
@@ -652,6 +652,9 @@
opl3sa2= [HW,OSS]
Format: <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
+ oprofile.timer= [HW]
+ Use timer interrupt instead of performance counters
+
optcd= [HW,CD]
Format: <io>
diff -Naur -X dontdiff linux-cvs/drivers/oprofile/oprof.c linux-me/drivers/oprofile/oprof.c
--- linux-cvs/drivers/oprofile/oprof.c 2003-05-10 17:30:28.000000000 +0100
+++ linux-me/drivers/oprofile/oprof.c 2003-05-26 04:52:51.000000000 +0100
@@ -11,6 +11,7 @@
#include <linux/module.h>
#include <linux/init.h>
#include <linux/oprofile.h>
+#include <linux/moduleparam.h>
#include <asm/semaphore.h>
#include "oprof.h"
@@ -24,6 +25,12 @@
static unsigned long is_setup;
static DECLARE_MUTEX(start_sem);
+/* timer
+ 0 - use performance monitoring hardware if available
+ 1 - use the timer int mechanism regardless
+ */
+static int timer = 0;
+
int oprofile_setup(void)
{
int err;
@@ -124,13 +131,16 @@
static int __init oprofile_init(void)
{
- int err;
+ int err = -ENODEV;
+
+ if (!timer) {
+ /* Architecture must fill in the interrupt ops and the
+ * logical CPU type, or we can fall back to the timer
+ * interrupt profiler.
+ */
+ err = oprofile_arch_init(&oprofile_ops);
+ }
- /* Architecture must fill in the interrupt ops and the
- * logical CPU type, or we can fall back to the timer
- * interrupt profiler.
- */
- err = oprofile_arch_init(&oprofile_ops);
if (err == -ENODEV) {
timer_init(&oprofile_ops);
err = 0;
@@ -163,6 +173,9 @@
module_init(oprofile_init);
module_exit(oprofile_exit);
+
+module_param_named(timer, timer, int, 0644);
+MODULE_PARM_DESC(timer, "force use of timer interrupt");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("John Levon <[email protected]>");