From: Adrian Hunter <adrian.hunter@intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
Ian Rogers <irogers@google.com>,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC 0/5] perf: Add ioctl to emit sideband events
Date: Tue, 18 Apr 2023 09:18:49 +0300 [thread overview]
Message-ID: <89733d35-0b71-615f-4fb8-55183585c67a@intel.com> (raw)
In-Reply-To: <20230417110221.GH83892@hirez.programming.kicks-ass.net>
On 17/04/23 14:02, Peter Zijlstra wrote:
> On Fri, Apr 14, 2023 at 11:22:55AM +0300, Adrian Hunter wrote:
>> Hi
>>
>> Here is a stab at adding an ioctl for sideband events.
>>
>> This is to overcome races when reading the same information
>> from /proc.
>
> What races? Are you talking about reading old state in /proc the kernel
> delivering a sideband event for the new state, and then you writing the
> old state out?
>
> Surely that's something perf tool can fix without kernel changes?
Yes, and it was a bit of a brain fart not to realise that.
There may still be corner cases, where different kinds of events are
interdependent, perhaps NAMESPACES events vs MMAP events could
have ordering issues.
Putting that aside, the ioctl may be quicker than reading from
/proc. I could get some numbers and see what people think.
next prev parent reply other threads:[~2023-04-18 6:18 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-14 8:22 [PATCH RFC 0/5] perf: Add ioctl to emit sideband events Adrian Hunter
2023-04-14 8:22 ` [PATCH RFC 1/5] " Adrian Hunter
2023-04-17 10:57 ` Peter Zijlstra
2023-04-18 6:29 ` Adrian Hunter
2023-04-14 8:22 ` [PATCH RFC 2/5] perf: Add fork to the sideband ioctl Adrian Hunter
2023-04-14 8:22 ` [PATCH RFC 3/5] perf: Add namespaces " Adrian Hunter
2023-04-14 8:22 ` [PATCH RFC 4/5] perf: Add comm " Adrian Hunter
2023-04-14 8:23 ` [PATCH RFC 5/5] perf: Add mmap " Adrian Hunter
2023-04-17 11:02 ` [PATCH RFC 0/5] perf: Add ioctl to emit sideband events Peter Zijlstra
2023-04-17 16:37 ` Ian Rogers
2023-04-18 7:03 ` Adrian Hunter
2023-04-18 6:18 ` Adrian Hunter [this message]
2023-04-18 13:36 ` Adrian Hunter
2023-04-18 15:51 ` Ian Rogers
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