* [PATCH bpf-next v1] libbpf: Add wakeup_events to creation options
@ 2023-02-01 9:00 Jon Doron
2023-02-01 19:57 ` Jiri Olsa
0 siblings, 1 reply; 4+ messages in thread
From: Jon Doron @ 2023-02-01 9:00 UTC (permalink / raw)
To: bpf, ast, andrii; +Cc: Jon Doron
From: Jon Doron <jond@wiz.io>
Add option to set when the perf buffer should wake up, by default the
perf buffer becomes signaled for every event that is being pushed to it.
In case of a high throughput of events it will be more efficient to wake
up only once you have X events ready to be read.
So your application can wakeup once and drain the entire perf buffer.
Signed-off-by: Jon Doron <jond@wiz.io>
---
tools/lib/bpf/libbpf.c | 4 ++--
tools/lib/bpf/libbpf.h | 1 +
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index eed5cec6f510..6b30ff13922b 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -11719,8 +11719,8 @@ struct perf_buffer *perf_buffer__new(int map_fd, size_t page_cnt,
attr.config = PERF_COUNT_SW_BPF_OUTPUT;
attr.type = PERF_TYPE_SOFTWARE;
attr.sample_type = PERF_SAMPLE_RAW;
- attr.sample_period = 1;
- attr.wakeup_events = 1;
+ attr.sample_period = OPTS_GET(opts, wakeup_events, 1);
+ attr.wakeup_events = OPTS_GET(opts, wakeup_events, 1);
p.attr = &attr;
p.sample_cb = sample_cb;
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 8777ff21ea1d..2e4bdfc58c82 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -1246,6 +1246,7 @@ typedef void (*perf_buffer_lost_fn)(void *ctx, int cpu, __u64 cnt);
/* common use perf buffer options */
struct perf_buffer_opts {
size_t sz;
+ __u32 wakeup_events;
};
#define perf_buffer_opts__last_field sz
--
2.39.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH bpf-next v1] libbpf: Add wakeup_events to creation options
2023-02-01 9:00 [PATCH bpf-next v1] libbpf: Add wakeup_events to creation options Jon Doron
@ 2023-02-01 19:57 ` Jiri Olsa
2023-02-02 1:28 ` Andrii Nakryiko
0 siblings, 1 reply; 4+ messages in thread
From: Jiri Olsa @ 2023-02-01 19:57 UTC (permalink / raw)
To: Jon Doron; +Cc: bpf, ast, andrii, Jon Doron
On Wed, Feb 01, 2023 at 11:00:09AM +0200, Jon Doron wrote:
> From: Jon Doron <jond@wiz.io>
>
> Add option to set when the perf buffer should wake up, by default the
> perf buffer becomes signaled for every event that is being pushed to it.
>
> In case of a high throughput of events it will be more efficient to wake
> up only once you have X events ready to be read.
>
> So your application can wakeup once and drain the entire perf buffer.
>
> Signed-off-by: Jon Doron <jond@wiz.io>
> ---
> tools/lib/bpf/libbpf.c | 4 ++--
> tools/lib/bpf/libbpf.h | 1 +
> 2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index eed5cec6f510..6b30ff13922b 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -11719,8 +11719,8 @@ struct perf_buffer *perf_buffer__new(int map_fd, size_t page_cnt,
> attr.config = PERF_COUNT_SW_BPF_OUTPUT;
> attr.type = PERF_TYPE_SOFTWARE;
> attr.sample_type = PERF_SAMPLE_RAW;
> - attr.sample_period = 1;
> - attr.wakeup_events = 1;
> + attr.sample_period = OPTS_GET(opts, wakeup_events, 1);
hm, but I think we still want every event.. setting sample_period to X
would store only every X-th bpf-output event, no?
jirka
> + attr.wakeup_events = OPTS_GET(opts, wakeup_events, 1);
>
> p.attr = &attr;
> p.sample_cb = sample_cb;
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index 8777ff21ea1d..2e4bdfc58c82 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -1246,6 +1246,7 @@ typedef void (*perf_buffer_lost_fn)(void *ctx, int cpu, __u64 cnt);
> /* common use perf buffer options */
> struct perf_buffer_opts {
> size_t sz;
> + __u32 wakeup_events;
> };
> #define perf_buffer_opts__last_field sz
>
> --
> 2.39.1
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH bpf-next v1] libbpf: Add wakeup_events to creation options
2023-02-01 19:57 ` Jiri Olsa
@ 2023-02-02 1:28 ` Andrii Nakryiko
2023-02-02 6:25 ` Jon Doron
0 siblings, 1 reply; 4+ messages in thread
From: Andrii Nakryiko @ 2023-02-02 1:28 UTC (permalink / raw)
To: Jiri Olsa; +Cc: Jon Doron, bpf, ast, andrii, Jon Doron
On Wed, Feb 1, 2023 at 11:57 AM Jiri Olsa <olsajiri@gmail.com> wrote:
>
> On Wed, Feb 01, 2023 at 11:00:09AM +0200, Jon Doron wrote:
> > From: Jon Doron <jond@wiz.io>
> >
> > Add option to set when the perf buffer should wake up, by default the
> > perf buffer becomes signaled for every event that is being pushed to it.
> >
> > In case of a high throughput of events it will be more efficient to wake
> > up only once you have X events ready to be read.
> >
> > So your application can wakeup once and drain the entire perf buffer.
> >
> > Signed-off-by: Jon Doron <jond@wiz.io>
> > ---
> > tools/lib/bpf/libbpf.c | 4 ++--
> > tools/lib/bpf/libbpf.h | 1 +
> > 2 files changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> > index eed5cec6f510..6b30ff13922b 100644
> > --- a/tools/lib/bpf/libbpf.c
> > +++ b/tools/lib/bpf/libbpf.c
> > @@ -11719,8 +11719,8 @@ struct perf_buffer *perf_buffer__new(int map_fd, size_t page_cnt,
> > attr.config = PERF_COUNT_SW_BPF_OUTPUT;
> > attr.type = PERF_TYPE_SOFTWARE;
> > attr.sample_type = PERF_SAMPLE_RAW;
> > - attr.sample_period = 1;
> > - attr.wakeup_events = 1;
> > + attr.sample_period = OPTS_GET(opts, wakeup_events, 1);
>
> hm, but I think we still want every event.. setting sample_period to X
> would store only every X-th bpf-output event, no?
seems like benchs/bench_ringbufs.c sets both sample_period and
wakeup_events, but it would be nice to make sure we do not lose events
with such configuration.
Let's add a selftest for this feature.
>
> jirka
>
> > + attr.wakeup_events = OPTS_GET(opts, wakeup_events, 1);
> >
> > p.attr = &attr;
> > p.sample_cb = sample_cb;
> > diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> > index 8777ff21ea1d..2e4bdfc58c82 100644
> > --- a/tools/lib/bpf/libbpf.h
> > +++ b/tools/lib/bpf/libbpf.h
> > @@ -1246,6 +1246,7 @@ typedef void (*perf_buffer_lost_fn)(void *ctx, int cpu, __u64 cnt);
> > /* common use perf buffer options */
> > struct perf_buffer_opts {
> > size_t sz;
> > + __u32 wakeup_events;
> > };
> > #define perf_buffer_opts__last_field sz
you need to update perf_buffer_opts__last_field to wakeup_events as well
> >
> > --
> > 2.39.1
> >
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH bpf-next v1] libbpf: Add wakeup_events to creation options
2023-02-02 1:28 ` Andrii Nakryiko
@ 2023-02-02 6:25 ` Jon Doron
0 siblings, 0 replies; 4+ messages in thread
From: Jon Doron @ 2023-02-02 6:25 UTC (permalink / raw)
To: Andrii Nakryiko; +Cc: Jiri Olsa, bpf, ast, andrii, Jon Doron
On 01/02/2023, Andrii Nakryiko wrote:
>On Wed, Feb 1, 2023 at 11:57 AM Jiri Olsa <olsajiri@gmail.com> wrote:
>>
>> On Wed, Feb 01, 2023 at 11:00:09AM +0200, Jon Doron wrote:
>> > From: Jon Doron <jond@wiz.io>
>> >
>> > Add option to set when the perf buffer should wake up, by default the
>> > perf buffer becomes signaled for every event that is being pushed to it.
>> >
>> > In case of a high throughput of events it will be more efficient to wake
>> > up only once you have X events ready to be read.
>> >
>> > So your application can wakeup once and drain the entire perf buffer.
>> >
>> > Signed-off-by: Jon Doron <jond@wiz.io>
>> > ---
>> > tools/lib/bpf/libbpf.c | 4 ++--
>> > tools/lib/bpf/libbpf.h | 1 +
>> > 2 files changed, 3 insertions(+), 2 deletions(-)
>> >
>> > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
>> > index eed5cec6f510..6b30ff13922b 100644
>> > --- a/tools/lib/bpf/libbpf.c
>> > +++ b/tools/lib/bpf/libbpf.c
>> > @@ -11719,8 +11719,8 @@ struct perf_buffer *perf_buffer__new(int map_fd, size_t page_cnt,
>> > attr.config = PERF_COUNT_SW_BPF_OUTPUT;
>> > attr.type = PERF_TYPE_SOFTWARE;
>> > attr.sample_type = PERF_SAMPLE_RAW;
>> > - attr.sample_period = 1;
>> > - attr.wakeup_events = 1;
>> > + attr.sample_period = OPTS_GET(opts, wakeup_events, 1);
>>
>> hm, but I think we still want every event.. setting sample_period to X
>> would store only every X-th bpf-output event, no?
>
>seems like benchs/bench_ringbufs.c sets both sample_period and
>wakeup_events, but it would be nice to make sure we do not lose events
>with such configuration.
>
>Let's add a selftest for this feature.
>
That's how it works, we wont be losing any events
>>
>> jirka
>>
>> > + attr.wakeup_events = OPTS_GET(opts, wakeup_events, 1);
>> >
>> > p.attr = &attr;
>> > p.sample_cb = sample_cb;
>> > diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
>> > index 8777ff21ea1d..2e4bdfc58c82 100644
>> > --- a/tools/lib/bpf/libbpf.h
>> > +++ b/tools/lib/bpf/libbpf.h
>> > @@ -1246,6 +1246,7 @@ typedef void (*perf_buffer_lost_fn)(void *ctx, int cpu, __u64 cnt);
>> > /* common use perf buffer options */
>> > struct perf_buffer_opts {
>> > size_t sz;
>> > + __u32 wakeup_events;
>> > };
>> > #define perf_buffer_opts__last_field sz
>
>you need to update perf_buffer_opts__last_field to wakeup_events as well
>
>
Done
>> >
>> > --
>> > 2.39.1
>> >
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2023-02-02 6:25 UTC | newest]
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2023-02-01 9:00 [PATCH bpf-next v1] libbpf: Add wakeup_events to creation options Jon Doron
2023-02-01 19:57 ` Jiri Olsa
2023-02-02 1:28 ` Andrii Nakryiko
2023-02-02 6:25 ` Jon Doron
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