Enable bpf programs to make use of rstat to collect cgroup hierarchical
stats efficiently:
- Add cgroup_rstat_updated() kfunc, for bpf progs that collect stats.
- Add cgroup_rstat_flush() kfunc, for bpf progs that read stats.
- Add an empty bpf_rstat_flush() hook that is called during rstat
flushing, for bpf progs that flush stats to attach to. Attaching a bpf
prog to this hook effectively registers it as a flush callback.
Signed-off-by: Yosry Ahmed <[email protected]>
---
kernel/cgroup/rstat.c | 46 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)
diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
index 24b5c2ab55983..94140bd0d02a4 100644
--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -3,6 +3,11 @@
#include <linux/sched/cputime.h>
+#include <linux/bpf.h>
+#include <linux/btf.h>
+#include <linux/btf_ids.h>
+
+
static DEFINE_SPINLOCK(cgroup_rstat_lock);
static DEFINE_PER_CPU(raw_spinlock_t, cgroup_rstat_cpu_lock);
@@ -141,6 +146,23 @@ static struct cgroup *cgroup_rstat_cpu_pop_updated(struct cgroup *pos,
return pos;
}
+/*
+ * A hook for bpf stat collectors to attach to and flush their stats.
+ * Together with providing bpf kfuncs for cgroup_rstat_updated() and
+ * cgroup_rstat_flush(), this enables a complete workflow where bpf progs that
+ * collect cgroup stats can integrate with rstat for efficient flushing.
+ *
+ * A static noinline declaration here could cause the compiler to optimize away
+ * the function. A global noinline declaration will keep the definition, but may
+ * optimize away the callsite. Therefore, __weak is needed to ensure that the
+ * call is still emitted, by telling the compiler that we don't know what the
+ * function might eventually be.
+ */
+__weak noinline void bpf_rstat_flush(struct cgroup *cgrp,
+ struct cgroup *parent, int cpu)
+{
+}
+
/* see cgroup_rstat_flush() */
static void cgroup_rstat_flush_locked(struct cgroup *cgrp, bool may_sleep)
__releases(&cgroup_rstat_lock) __acquires(&cgroup_rstat_lock)
@@ -168,6 +190,7 @@ static void cgroup_rstat_flush_locked(struct cgroup *cgrp, bool may_sleep)
struct cgroup_subsys_state *css;
cgroup_base_stat_flush(pos, cpu);
+ bpf_rstat_flush(pos, cgroup_parent(pos), cpu);
rcu_read_lock();
list_for_each_entry_rcu(css, &pos->rstat_css_list,
@@ -469,3 +492,26 @@ void cgroup_base_stat_cputime_show(struct seq_file *seq)
"system_usec %llu\n",
usage, utime, stime);
}
+
+/* Add bpf kfuncs for cgroup_rstat_updated() and cgroup_rstat_flush() */
+BTF_SET_START(bpf_rstat_check_kfunc_ids)
+BTF_ID(func, cgroup_rstat_updated)
+BTF_ID(func, cgroup_rstat_flush)
+BTF_SET_END(bpf_rstat_check_kfunc_ids)
+
+BTF_SET_START(bpf_rstat_sleepable_kfunc_ids)
+BTF_ID(func, cgroup_rstat_flush)
+BTF_SET_END(bpf_rstat_sleepable_kfunc_ids)
+
+static const struct btf_kfunc_id_set bpf_rstat_kfunc_set = {
+ .owner = THIS_MODULE,
+ .check_set = &bpf_rstat_check_kfunc_ids,
+ .sleepable_set = &bpf_rstat_sleepable_kfunc_ids,
+};
+
+static int __init bpf_rstat_kfunc_init(void)
+{
+ return register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING,
+ &bpf_rstat_kfunc_set);
+}
+late_initcall(bpf_rstat_kfunc_init);
--
2.36.1.476.g0c4daa206d-goog
Hi Yosry,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on bpf-next/master]
url: https://github.com/intel-lab-lkp/linux/commits/Yosry-Ahmed/bpf-rstat-cgroup-hierarchical-stats/20220611-034720
base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: um-i386_defconfig (https://download.01.org/0day-ci/archive/20220611/[email protected]/config)
compiler: gcc-11 (Debian 11.3.0-3) 11.3.0
reproduce (this is a W=1 build):
# https://github.com/intel-lab-lkp/linux/commit/83f297e2b47dc41b511f071b9eadf38339387b41
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Yosry-Ahmed/bpf-rstat-cgroup-hierarchical-stats/20220611-034720
git checkout 83f297e2b47dc41b511f071b9eadf38339387b41
# save the config file
mkdir build_dir && cp config build_dir/.config
make W=1 O=build_dir ARCH=um SUBARCH=i386 SHELL=/bin/bash kernel/cgroup/
If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <[email protected]>
All warnings (new ones prefixed by >>):
>> kernel/cgroup/rstat.c:161:22: warning: no previous prototype for 'bpf_rstat_flush' [-Wmissing-prototypes]
161 | __weak noinline void bpf_rstat_flush(struct cgroup *cgrp,
| ^~~~~~~~~~~~~~~
kernel/cgroup/rstat.c:509:10: error: 'const struct btf_kfunc_id_set' has no member named 'sleepable_set'; did you mean 'release_set'?
509 | .sleepable_set = &bpf_rstat_sleepable_kfunc_ids,
| ^~~~~~~~~~~~~
| release_set
>> kernel/cgroup/rstat.c:509:27: warning: excess elements in struct initializer
509 | .sleepable_set = &bpf_rstat_sleepable_kfunc_ids,
| ^
kernel/cgroup/rstat.c:509:27: note: (near initialization for 'bpf_rstat_kfunc_set')
vim +/bpf_rstat_flush +161 kernel/cgroup/rstat.c
148
149 /*
150 * A hook for bpf stat collectors to attach to and flush their stats.
151 * Together with providing bpf kfuncs for cgroup_rstat_updated() and
152 * cgroup_rstat_flush(), this enables a complete workflow where bpf progs that
153 * collect cgroup stats can integrate with rstat for efficient flushing.
154 *
155 * A static noinline declaration here could cause the compiler to optimize away
156 * the function. A global noinline declaration will keep the definition, but may
157 * optimize away the callsite. Therefore, __weak is needed to ensure that the
158 * call is still emitted, by telling the compiler that we don't know what the
159 * function might eventually be.
160 */
> 161 __weak noinline void bpf_rstat_flush(struct cgroup *cgrp,
162 struct cgroup *parent, int cpu)
163 {
164 }
165
--
0-DAY CI Kernel Test Service
https://01.org/lkp
On Fri, Jun 10, 2022 at 2:23 PM kernel test robot <[email protected]> wrote:
>
> Hi Yosry,
>
> Thank you for the patch! Yet something to improve:
>
> [auto build test ERROR on bpf-next/master]
>
> url: https://github.com/intel-lab-lkp/linux/commits/Yosry-Ahmed/bpf-rstat-cgroup-hierarchical-stats/20220611-034720
> base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
> config: um-i386_defconfig (https://download.01.org/0day-ci/archive/20220611/[email protected]/config)
> compiler: gcc-11 (Debian 11.3.0-3) 11.3.0
> reproduce (this is a W=1 build):
> # https://github.com/intel-lab-lkp/linux/commit/83f297e2b47dc41b511f071b9eadf38339387b41
> git remote add linux-review https://github.com/intel-lab-lkp/linux
> git fetch --no-tags linux-review Yosry-Ahmed/bpf-rstat-cgroup-hierarchical-stats/20220611-034720
> git checkout 83f297e2b47dc41b511f071b9eadf38339387b41
> # save the config file
> mkdir build_dir && cp config build_dir/.config
> make W=1 O=build_dir ARCH=um SUBARCH=i386 SHELL=/bin/bash
>
> If you fix the issue, kindly add following tag where applicable
> Reported-by: kernel test robot <[email protected]>
>
> All errors (new ones prefixed by >>):
>
> kernel/cgroup/rstat.c:161:22: warning: no previous prototype for 'bpf_rstat_flush' [-Wmissing-prototypes]
> 161 | __weak noinline void bpf_rstat_flush(struct cgroup *cgrp,
> | ^~~~~~~~~~~~~~~
> >> kernel/cgroup/rstat.c:509:10: error: 'const struct btf_kfunc_id_set' has no member named 'sleepable_set'; did you mean 'release_set'?
> 509 | .sleepable_set = &bpf_rstat_sleepable_kfunc_ids,
> | ^~~~~~~~~~~~~
> | release_set
> kernel/cgroup/rstat.c:509:27: warning: excess elements in struct initializer
> 509 | .sleepable_set = &bpf_rstat_sleepable_kfunc_ids,
> | ^
> kernel/cgroup/rstat.c:509:27: note: (near initialization for 'bpf_rstat_kfunc_set')
>
>
> vim +509 kernel/cgroup/rstat.c
>
> 505
> 506 static const struct btf_kfunc_id_set bpf_rstat_kfunc_set = {
> 507 .owner = THIS_MODULE,
> 508 .check_set = &bpf_rstat_check_kfunc_ids,
> > 509 .sleepable_set = &bpf_rstat_sleepable_kfunc_ids,
> 510 };
> 511
>
> --
> 0-DAY CI Kernel Test Service
> https://01.org/lkp
AFAICT these failures are because the patch series depends on a patch
in the mailing list [1] that is not in bpf-next, as explained by the
cover letter.
[1] https://lore.kernel.org/bpf/[email protected]/
Hi Yosry,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on bpf-next/master]
url: https://github.com/intel-lab-lkp/linux/commits/Yosry-Ahmed/bpf-rstat-cgroup-hierarchical-stats/20220611-034720
base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: um-i386_defconfig (https://download.01.org/0day-ci/archive/20220611/[email protected]/config)
compiler: gcc-11 (Debian 11.3.0-3) 11.3.0
reproduce (this is a W=1 build):
# https://github.com/intel-lab-lkp/linux/commit/83f297e2b47dc41b511f071b9eadf38339387b41
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Yosry-Ahmed/bpf-rstat-cgroup-hierarchical-stats/20220611-034720
git checkout 83f297e2b47dc41b511f071b9eadf38339387b41
# save the config file
mkdir build_dir && cp config build_dir/.config
make W=1 O=build_dir ARCH=um SUBARCH=i386 SHELL=/bin/bash
If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <[email protected]>
All errors (new ones prefixed by >>):
kernel/cgroup/rstat.c:161:22: warning: no previous prototype for 'bpf_rstat_flush' [-Wmissing-prototypes]
161 | __weak noinline void bpf_rstat_flush(struct cgroup *cgrp,
| ^~~~~~~~~~~~~~~
>> kernel/cgroup/rstat.c:509:10: error: 'const struct btf_kfunc_id_set' has no member named 'sleepable_set'; did you mean 'release_set'?
509 | .sleepable_set = &bpf_rstat_sleepable_kfunc_ids,
| ^~~~~~~~~~~~~
| release_set
kernel/cgroup/rstat.c:509:27: warning: excess elements in struct initializer
509 | .sleepable_set = &bpf_rstat_sleepable_kfunc_ids,
| ^
kernel/cgroup/rstat.c:509:27: note: (near initialization for 'bpf_rstat_kfunc_set')
vim +509 kernel/cgroup/rstat.c
505
506 static const struct btf_kfunc_id_set bpf_rstat_kfunc_set = {
507 .owner = THIS_MODULE,
508 .check_set = &bpf_rstat_check_kfunc_ids,
> 509 .sleepable_set = &bpf_rstat_sleepable_kfunc_ids,
510 };
511
--
0-DAY CI Kernel Test Service
https://01.org/lkp
Hi Yosry,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on bpf-next/master]
url: https://github.com/intel-lab-lkp/linux/commits/Yosry-Ahmed/bpf-rstat-cgroup-hierarchical-stats/20220611-034720
base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: hexagon-randconfig-r012-20220611 (https://download.01.org/0day-ci/archive/20220611/[email protected]/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project ff4abe755279a3a47cc416ef80dbc900d9a98a19)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/83f297e2b47dc41b511f071b9eadf38339387b41
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Yosry-Ahmed/bpf-rstat-cgroup-hierarchical-stats/20220611-034720
git checkout 83f297e2b47dc41b511f071b9eadf38339387b41
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash kernel/cgroup/
If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <[email protected]>
All error/warnings (new ones prefixed by >>):
>> kernel/cgroup/rstat.c:161:22: warning: no previous prototype for function 'bpf_rstat_flush' [-Wmissing-prototypes]
__weak noinline void bpf_rstat_flush(struct cgroup *cgrp,
^
kernel/cgroup/rstat.c:161:17: note: declare 'static' if the function is not intended to be used outside of this translation unit
__weak noinline void bpf_rstat_flush(struct cgroup *cgrp,
^
static
>> kernel/cgroup/rstat.c:509:3: error: field designator 'sleepable_set' does not refer to any field in type 'const struct btf_kfunc_id_set'
.sleepable_set = &bpf_rstat_sleepable_kfunc_ids,
^
1 warning and 1 error generated.
vim +509 kernel/cgroup/rstat.c
505
506 static const struct btf_kfunc_id_set bpf_rstat_kfunc_set = {
507 .owner = THIS_MODULE,
508 .check_set = &bpf_rstat_check_kfunc_ids,
> 509 .sleepable_set = &bpf_rstat_sleepable_kfunc_ids,
510 };
511
--
0-DAY CI Kernel Test Service
https://01.org/lkp
On Fri, Jun 10, 2022 at 02:30:00PM -0700, Yosry Ahmed wrote:
>
> AFAICT these failures are because the patch series depends on a patch
> in the mailing list [1] that is not in bpf-next, as explained by the
> cover letter.
>
> [1] https://lore.kernel.org/bpf/[email protected]/
You probably want to rebase and include that patch as patch 1 in your series
preserving Benjamin's SOB and cc-ing him on the series.
Otherwise we cannot land the set, BPF CI cannot test it, and review is hard to do.
On Sat, Jun 11, 2022 at 12:57 PM Alexei Starovoitov
<[email protected]> wrote:
>
> On Fri, Jun 10, 2022 at 02:30:00PM -0700, Yosry Ahmed wrote:
> >
> > AFAICT these failures are because the patch series depends on a patch
> > in the mailing list [1] that is not in bpf-next, as explained by the
> > cover letter.
> >
> > [1] https://lore.kernel.org/bpf/[email protected]/
>
> You probably want to rebase and include that patch as patch 1 in your series
> preserving Benjamin's SOB and cc-ing him on the series.
> Otherwise we cannot land the set, BPF CI cannot test it, and review is hard to do.
Sounds good. Will rebase do that and send a v3.
On 6/10/22 12:44 PM, Yosry Ahmed wrote:
> Enable bpf programs to make use of rstat to collect cgroup hierarchical
> stats efficiently:
> - Add cgroup_rstat_updated() kfunc, for bpf progs that collect stats.
> - Add cgroup_rstat_flush() kfunc, for bpf progs that read stats.
> - Add an empty bpf_rstat_flush() hook that is called during rstat
> flushing, for bpf progs that flush stats to attach to. Attaching a bpf
> prog to this hook effectively registers it as a flush callback.
>
> Signed-off-by: Yosry Ahmed <[email protected]>
Acked-by: Yonghong Song <[email protected]>