linux-kernel - Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer

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Date:	Tue, 8 Mar 2016 14:49:01 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Wang Nan <wangnan0@...wei.com>, mingo@...hat.com,
	linux-kernel@...r.kernel.org, He Kuang <hekuang@...wei.com>,
	Alexei Starovoitov <ast@...nel.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Brendan Gregg <brendan.d.gregg@...il.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Zefan Li <lizefan@...wei.com>, pi3orama@....com
Subject: Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer


* Peter Zijlstra <peterz@...radead.org> wrote:

> On Mon, Mar 07, 2016 at 03:50:14AM +0000, Wang Nan wrote:
> > This patch set has been posted multiple times (with and without
> > corresponding 'perf tool' patches), and doesn't receive further
> > comment. I think it should be okay to merge them into mainline.
> > There are many perf's improvement depend on it. However, Peter
> > is not responsive after I fixed some problems he pointed out.
> > 
> > Introduces 'write_backward' into perf_event_attr, allows kernel
> > writing the ring buffer from the end of it. This feature allows
> > extracting data from overwritable ring buffer.
> > 
> > Wang Nan (5):
> >   perf core: Introduce new ioctl options to pause and resume ring buffer
> >   perf core: Set event's default overflow_handler
> >   perf core: Prepare writing into ring buffer from end
> >   perf core: Add backward attribute to perf event
> >   perf core: Reduce perf event output overhead by new overflow handler
> 
> perf kernel features are currently on hold until I can manage to run a
> fuzzer for more than a few minutes without my machine having a seizure.

Btw., could you describe exactly what commands you are running, with what 
configuration options (if that matters), so that people who'd like our feature 
freeze to be lifted can help out?

Thanks,

	Ingo