Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

于 2015/10/23 23:12, Peter Zijlstra 写道: > On Fri, Oct 23, 2015 at 02:52:11PM +0200, Peter Zijlstra wrote: >> On Thu, Oct 22, 2015 at 06:28:22PM +0800, Wangnan (F) wrote: >>> information to analysis when glitch happen. Another way we are trying to >>> implement >>> now is to dynamically turn events

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

于 2015/10/23 23:12, Peter Zijlstra 写道: > On Fri, Oct 23, 2015 at 02:52:11PM +0200, Peter Zijlstra wrote: >> On Thu, Oct 22, 2015 at 06:28:22PM +0800, Wangnan (F) wrote: >>> information to analysis when glitch happen. Another way we are trying to >>> implement >>> now is to dynamically turn events

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Fri, Oct 23, 2015 at 02:52:11PM +0200, Peter Zijlstra wrote: > On Thu, Oct 22, 2015 at 06:28:22PM +0800, Wangnan (F) wrote: > > information to analysis when glitch happen. Another way we are trying to > > implement > > now is to dynamically turn events on and off, or at least enable/disable > >

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Thu, Oct 22, 2015 at 06:28:22PM +0800, Wangnan (F) wrote: > information to analysis when glitch happen. Another way we are trying to > implement > now is to dynamically turn events on and off, or at least enable/disable > sampling dynamically because the overhead of copying those samples > is a

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Thu, Oct 22, 2015 at 06:28:22PM +0800, Wangnan (F) wrote: > information to analysis when glitch happen. Another way we are trying to > implement > now is to dynamically turn events on and off, or at least enable/disable > sampling dynamically because the overhead of copying those samples > is a

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Fri, Oct 23, 2015 at 02:52:11PM +0200, Peter Zijlstra wrote: > On Thu, Oct 22, 2015 at 06:28:22PM +0800, Wangnan (F) wrote: > > information to analysis when glitch happen. Another way we are trying to > > implement > > now is to dynamically turn events on and off, or at least enable/disable > >

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 2015/10/22 17:06, Peter Zijlstra wrote: On Wed, Oct 21, 2015 at 02:19:49PM -0700, Alexei Starovoitov wrote: Urgh, that's still horridly inconsistent. Can we please come up with a consistent interface to perf? My suggestion was to do ioctl(enable/disable) of events from userspace after

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Thu, Oct 22, 2015 at 11:12:16AM +0800, Wangnan (F) wrote: > On 2015/10/22 11:09, Alexei Starovoitov wrote: > >On 10/21/15 6:56 PM, Wangnan (F) wrote: > >>>One alternative solution I can image is to attach a BPF program > >>>at sampling like kprobe, and return 0 if we don't want sampling >

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Thu, Oct 22, 2015 at 03:51:37PM +0800, Wangnan (F) wrote: > Because I'm not very sure what the meaning of "inconsistent" in > Peter's words... What's inconsistent is that some perf actions can be done only on local events while others can be done on !local. And I can't say I particularly like

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Wed, Oct 21, 2015 at 02:19:49PM -0700, Alexei Starovoitov wrote: > >Urgh, that's still horridly inconsistent. Can we please come up with a > >consistent interface to perf? > My suggestion was to do ioctl(enable/disable) of events from userspace > after receiving notification from kernel via

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 2015/10/22 15:39, Ingo Molnar wrote: * Wangnan (F) wrote: [SNIP] In summary, your either-or logic doesn't hold in BPF world. A BPF program can only access perf event in a highly restricted way. We don't allow it calling perf_event_read_local() across core, so it can't. Urgh, that's

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

* Wangnan (F) wrote: > > > On 2015/10/22 0:57, Peter Zijlstra wrote: > >On Wed, Oct 21, 2015 at 11:06:47PM +0800, pi3orama wrote: > >>>So explain; how does this eBPF stuff work. > >>I think I get your point this time, and let me explain the eBPF stuff to > >>you. > >> > >>You are aware that

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

* Wangnan (F) wrote: > > > On 2015/10/22 0:57, Peter Zijlstra wrote: > >On Wed, Oct 21, 2015 at 11:06:47PM +0800, pi3orama wrote: > >>>So explain; how does this eBPF stuff work. > >>I think I get your point this time, and let me explain the eBPF stuff to > >>you. > >> >

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 2015/10/22 15:39, Ingo Molnar wrote: * Wangnan (F) wrote: [SNIP] In summary, your either-or logic doesn't hold in BPF world. A BPF program can only access perf event in a highly restricted way. We don't allow it calling perf_event_read_local() across core, so it

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Thu, Oct 22, 2015 at 03:51:37PM +0800, Wangnan (F) wrote: > Because I'm not very sure what the meaning of "inconsistent" in > Peter's words... What's inconsistent is that some perf actions can be done only on local events while others can be done on !local. And I can't say I particularly like

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Wed, Oct 21, 2015 at 02:19:49PM -0700, Alexei Starovoitov wrote: > >Urgh, that's still horridly inconsistent. Can we please come up with a > >consistent interface to perf? > My suggestion was to do ioctl(enable/disable) of events from userspace > after receiving notification from kernel via

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Thu, Oct 22, 2015 at 11:12:16AM +0800, Wangnan (F) wrote: > On 2015/10/22 11:09, Alexei Starovoitov wrote: > >On 10/21/15 6:56 PM, Wangnan (F) wrote: > >>>One alternative solution I can image is to attach a BPF program > >>>at sampling like kprobe, and return 0 if we don't want sampling >

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 2015/10/22 17:06, Peter Zijlstra wrote: On Wed, Oct 21, 2015 at 02:19:49PM -0700, Alexei Starovoitov wrote: Urgh, that's still horridly inconsistent. Can we please come up with a consistent interface to perf? My suggestion was to do ioctl(enable/disable) of events from userspace after

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 10/21/15 8:12 PM, Wangnan (F) wrote: On 2015/10/22 11:09, Alexei Starovoitov wrote: On 10/21/15 6:56 PM, Wangnan (F) wrote: One alternative solution I can image is to attach a BPF program at sampling like kprobe, and return 0 if we don't want sampling take action. Thought? Do you think

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 2015/10/22 11:09, Alexei Starovoitov wrote: On 10/21/15 6:56 PM, Wangnan (F) wrote: One alternative solution I can image is to attach a BPF program at sampling like kprobe, and return 0 if we don't want sampling take action. Thought? Do you think attaching BPF programs to sampling is an

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 10/21/15 6:56 PM, Wangnan (F) wrote: One alternative solution I can image is to attach a BPF program at sampling like kprobe, and return 0 if we don't want sampling take action. Thought? Do you think attaching BPF programs to sampling is an acceptable idea? If you mean to extend 'filter'

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 2015/10/22 0:57, Peter Zijlstra wrote: On Wed, Oct 21, 2015 at 11:06:47PM +0800, pi3orama wrote: So explain; how does this eBPF stuff work. I think I get your point this time, and let me explain the eBPF stuff to you. You are aware that BPF programmer can break the system in this way:

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

Hi Alexei, On 2015/10/21 21:42, Wangnan (F) wrote: One alternative solution I can image is to attach a BPF program at sampling like kprobe, and return 0 if we don't want sampling take action. Thought? Do you think attaching BPF programs to sampling is an acceptable idea? Thank you.

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 10/21/15 9:57 AM, Peter Zijlstra wrote: In summary, your either-or logic doesn't hold in BPF world. A BPF >program can only access perf event in a highly restricted way. We >don't allow it calling perf_event_read_local() across core, so it >can't. That's actually broken. My fault as well,

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Wed, Oct 21, 2015 at 11:06:47PM +0800, pi3orama wrote: > > So explain; how does this eBPF stuff work. > > I think I get your point this time, and let me explain the eBPF stuff to you. > > You are aware that BPF programmer can break the system in this way: > > A=get_non_local_perf_event() >

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

发自我的 iPhone > 在 2015年10月21日，下午10:09，Peter Zijlstra 写道： > > On Wed, Oct 21, 2015 at 10:01:46PM +0800, pi3orama wrote: >>> 在 2015年10月21日，下午9:49，Peter Zijlstra 写道： >>> On Wed, Oct 21, 2015 at 09:42:12PM +0800, Wangnan (F) wrote: How can an eBPF program access a !local event:

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Wed, Oct 21, 2015 at 10:01:46PM +0800, pi3orama wrote: > > 在 2015年10月21日，下午9:49，Peter Zijlstra 写道： > > > >> On Wed, Oct 21, 2015 at 09:42:12PM +0800, Wangnan (F) wrote: > >> How can an eBPF program access a !local event: > >> > >> when creating perf event array we don't care which perf event

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

发自我的 iPhone > 在 2015年10月21日，下午9:49，Peter Zijlstra 写道： > >> On Wed, Oct 21, 2015 at 09:42:12PM +0800, Wangnan (F) wrote: >> How can an eBPF program access a !local event: >> >> when creating perf event array we don't care which perf event >> is for which CPU, so perf program can access any

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Wed, Oct 21, 2015 at 09:42:12PM +0800, Wangnan (F) wrote: > How can an eBPF program access a !local event: > > when creating perf event array we don't care which perf event > is for which CPU, so perf program can access any perf event in > that array. So what is stopping the eBPF thing from

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 2015/10/21 20:17, Peter Zijlstra wrote: On Wed, Oct 21, 2015 at 07:49:34PM +0800, Wangnan (F) wrote: If our task is sampling cycle events during a function is running, and if two cores start that function overlap: Time: ...A Core 0: sys_write\

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Wed, Oct 21, 2015 at 07:49:34PM +0800, Wangnan (F) wrote: > If our task is sampling cycle events during a function is running, > and if two cores start that function overlap: > > Time: ...A > Core 0: sys_write\ > \ >\ > Core

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 2015/10/21 19:56, Peter Zijlstra wrote: On Wed, Oct 21, 2015 at 07:34:28PM +0800, Wangnan (F) wrote: If you want to actually disable the event: pmu->stop() will make it stop, and you can restart using pmu->start().xiezuo I also prefer totally disabling event because our goal is to reduce

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Wed, Oct 21, 2015 at 07:34:28PM +0800, Wangnan (F) wrote: > >If you want to actually disable the event: pmu->stop() will make it > >stop, and you can restart using pmu->start().xiezuo > > I also prefer totally disabling event because our goal is to reduce > sampling overhead as mush as

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 2015/10/21 19:33, Peter Zijlstra wrote: On Wed, Oct 21, 2015 at 06:31:04PM +0800, xiakaixu wrote: The RFC patch set contains the necessary commit log [1]. That's of course the wrong place, this should be in the patch's Changelog. It doesn't become less relevant. In some scenarios we

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 2015/10/21 17:12, Peter Zijlstra wrote: On Tue, Oct 20, 2015 at 03:53:02PM -0700, Alexei Starovoitov wrote: On 10/20/15 12:22 AM, Kaixu Xia wrote: diff --git a/kernel/events/core.c b/kernel/events/core.c index b11756f..5219635 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Wed, Oct 21, 2015 at 06:31:04PM +0800, xiakaixu wrote: > The RFC patch set contains the necessary commit log [1]. That's of course the wrong place, this should be in the patch's Changelog. It doesn't become less relevant. > In some scenarios we don't want to output trace data when perf

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

于 2015/10/21 17:12, Peter Zijlstra 写道: > On Tue, Oct 20, 2015 at 03:53:02PM -0700, Alexei Starovoitov wrote: >> On 10/20/15 12:22 AM, Kaixu Xia wrote: >>> diff --git a/kernel/events/core.c b/kernel/events/core.c >>> index b11756f..5219635 100644 >>> --- a/kernel/events/core.c >>> +++

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Tue, Oct 20, 2015 at 03:53:02PM -0700, Alexei Starovoitov wrote: > On 10/20/15 12:22 AM, Kaixu Xia wrote: > >diff --git a/kernel/events/core.c b/kernel/events/core.c > >index b11756f..5219635 100644 > >--- a/kernel/events/core.c > >+++ b/kernel/events/core.c > >@@ -6337,6 +6337,9 @@ static int

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Wed, Oct 21, 2015 at 10:01:46PM +0800, pi3orama wrote: > > 在 2015年10月21日，下午9:49，Peter Zijlstra 写道： > > > >> On Wed, Oct 21, 2015 at 09:42:12PM +0800, Wangnan (F) wrote: > >> How can an eBPF program access a !local event: > >> > >> when creating perf event array we don't

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 2015/10/21 20:17, Peter Zijlstra wrote: On Wed, Oct 21, 2015 at 07:49:34PM +0800, Wangnan (F) wrote: If our task is sampling cycle events during a function is running, and if two cores start that function overlap: Time: ...A Core 0: sys_write\

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

发自我的 iPhone > 在 2015年10月21日，下午9:49，Peter Zijlstra 写道： > >> On Wed, Oct 21, 2015 at 09:42:12PM +0800, Wangnan (F) wrote: >> How can an eBPF program access a !local event: >> >> when creating perf event array we don't care which perf event >> is for which CPU, so perf

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Wed, Oct 21, 2015 at 09:42:12PM +0800, Wangnan (F) wrote: > How can an eBPF program access a !local event: > > when creating perf event array we don't care which perf event > is for which CPU, so perf program can access any perf event in > that array. So what is stopping the eBPF thing from

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Wed, Oct 21, 2015 at 11:06:47PM +0800, pi3orama wrote: > > So explain; how does this eBPF stuff work. > > I think I get your point this time, and let me explain the eBPF stuff to you. > > You are aware that BPF programmer can break the system in this way: > > A=get_non_local_perf_event() >

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 10/21/15 9:57 AM, Peter Zijlstra wrote: In summary, your either-or logic doesn't hold in BPF world. A BPF >program can only access perf event in a highly restricted way. We >don't allow it calling perf_event_read_local() across core, so it >can't. That's actually broken. My fault as well,

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

Hi Alexei, On 2015/10/21 21:42, Wangnan (F) wrote: One alternative solution I can image is to attach a BPF program at sampling like kprobe, and return 0 if we don't want sampling take action. Thought? Do you think attaching BPF programs to sampling is an acceptable idea? Thank you.

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

发自我的 iPhone > 在 2015年10月21日，下午10:09，Peter Zijlstra 写道： > > On Wed, Oct 21, 2015 at 10:01:46PM +0800, pi3orama wrote: >>> 在 2015年10月21日，下午9:49，Peter Zijlstra 写道： >>> On Wed, Oct 21, 2015 at 09:42:12PM +0800, Wangnan (F) wrote: How can an

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 2015/10/22 0:57, Peter Zijlstra wrote: On Wed, Oct 21, 2015 at 11:06:47PM +0800, pi3orama wrote: So explain; how does this eBPF stuff work. I think I get your point this time, and let me explain the eBPF stuff to you. You are aware that BPF programmer can break the system in this way:

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 10/21/15 6:56 PM, Wangnan (F) wrote: One alternative solution I can image is to attach a BPF program at sampling like kprobe, and return 0 if we don't want sampling take action. Thought? Do you think attaching BPF programs to sampling is an acceptable idea? If you mean to extend 'filter'

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 2015/10/22 11:09, Alexei Starovoitov wrote: On 10/21/15 6:56 PM, Wangnan (F) wrote: One alternative solution I can image is to attach a BPF program at sampling like kprobe, and return 0 if we don't want sampling take action. Thought? Do you think attaching BPF programs to sampling is an

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 10/21/15 8:12 PM, Wangnan (F) wrote: On 2015/10/22 11:09, Alexei Starovoitov wrote: On 10/21/15 6:56 PM, Wangnan (F) wrote: One alternative solution I can image is to attach a BPF program at sampling like kprobe, and return 0 if we don't want sampling take action. Thought? Do you think

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Tue, Oct 20, 2015 at 03:53:02PM -0700, Alexei Starovoitov wrote: > On 10/20/15 12:22 AM, Kaixu Xia wrote: > >diff --git a/kernel/events/core.c b/kernel/events/core.c > >index b11756f..5219635 100644 > >--- a/kernel/events/core.c > >+++ b/kernel/events/core.c > >@@ -6337,6 +6337,9 @@ static int

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

于 2015/10/21 17:12, Peter Zijlstra 写道: > On Tue, Oct 20, 2015 at 03:53:02PM -0700, Alexei Starovoitov wrote: >> On 10/20/15 12:22 AM, Kaixu Xia wrote: >>> diff --git a/kernel/events/core.c b/kernel/events/core.c >>> index b11756f..5219635 100644 >>> --- a/kernel/events/core.c >>> +++

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Wed, Oct 21, 2015 at 06:31:04PM +0800, xiakaixu wrote: > The RFC patch set contains the necessary commit log [1]. That's of course the wrong place, this should be in the patch's Changelog. It doesn't become less relevant. > In some scenarios we don't want to output trace data when perf

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 2015/10/21 19:56, Peter Zijlstra wrote: On Wed, Oct 21, 2015 at 07:34:28PM +0800, Wangnan (F) wrote: If you want to actually disable the event: pmu->stop() will make it stop, and you can restart using pmu->start().xiezuo I also prefer totally disabling event because our goal is to reduce

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 2015/10/21 19:33, Peter Zijlstra wrote: On Wed, Oct 21, 2015 at 06:31:04PM +0800, xiakaixu wrote: The RFC patch set contains the necessary commit log [1]. That's of course the wrong place, this should be in the patch's Changelog. It doesn't become less relevant. In some scenarios we

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Wed, Oct 21, 2015 at 07:34:28PM +0800, Wangnan (F) wrote: > >If you want to actually disable the event: pmu->stop() will make it > >stop, and you can restart using pmu->start().xiezuo > > I also prefer totally disabling event because our goal is to reduce > sampling overhead as mush as

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 2015/10/21 17:12, Peter Zijlstra wrote: On Tue, Oct 20, 2015 at 03:53:02PM -0700, Alexei Starovoitov wrote: On 10/20/15 12:22 AM, Kaixu Xia wrote: diff --git a/kernel/events/core.c b/kernel/events/core.c index b11756f..5219635 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On Wed, Oct 21, 2015 at 07:49:34PM +0800, Wangnan (F) wrote: > If our task is sampling cycle events during a function is running, > and if two cores start that function overlap: > > Time: ...A > Core 0: sys_write\ > \ >\ > Core

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 10/20/15 12:22 AM, Kaixu Xia wrote: diff --git a/kernel/events/core.c b/kernel/events/core.c index b11756f..5219635 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6337,6 +6337,9 @@ static int __perf_event_overflow(struct perf_event *event,

Re: [PATCH V5 1/1] bpf: control events stored in PERF_EVENT_ARRAY maps trace data output when perf sampling

On 10/20/15 12:22 AM, Kaixu Xia wrote: diff --git a/kernel/events/core.c b/kernel/events/core.c index b11756f..5219635 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -6337,6 +6337,9 @@ static int __perf_event_overflow(struct perf_event *event,