Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932164AbcCHN6g (ORCPT ); Tue, 8 Mar 2016 08:58:36 -0500 Received: from casper.infradead.org ([85.118.1.10]:33350 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753002AbcCHN6O (ORCPT ); Tue, 8 Mar 2016 08:58:14 -0500 Date: Tue, 8 Mar 2016 14:57:59 +0100 From: Peter Zijlstra To: Ingo Molnar Cc: Wang Nan , mingo@redhat.com, linux-kernel@vger.kernel.org, He Kuang , Alexei Starovoitov , Arnaldo Carvalho de Melo , Brendan Gregg , Jiri Olsa , Masami Hiramatsu , Namhyung Kim , Zefan Li , pi3orama@163.com Subject: Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Message-ID: <20160308135759.GH6356@twins.programming.kicks-ass.net> References: <1457322619-170254-1-git-send-email-wangnan0@huawei.com> <20160308134454.GY6344@twins.programming.kicks-ass.net> <20160308134901.GC19756@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160308134901.GC19756@gmail.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2779 Lines: 76 On Tue, Mar 08, 2016 at 02:49:01PM +0100, Ingo Molnar wrote: > > * Peter Zijlstra 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? Mostly syz-kaller, but also Vince's perf-fuzzer and your perf-stress script, which I'm not sure is publicly available. perf_fuzzer lives at: https://github.com/deater/perf_event_tests.git Here's a thread on syz-kaller: lkml.kernel.org/r/CACT4Y+Ym0TZLkmRrM0ZGgLpu8kqS-YjoWTMrvaLz=tx2tnyO3w@mail.gmail.com If things have shifted again I'm sure Dmitry is willing to help. I run the thing natively on actual real hardware, which ensure I get to test the PMU drivers too. # cat go-fuzz.sh #!/bin/bash echo 1 > /proc/sys/kernel/traceoff_on_warning echo 1 > /debug/tracing/options/stacktrace echo 1 > /debug/tracing/events/sched/enable cd gopath/src/github.com/google/syzkaller/ ./bin/syz-manager -config perf.cfg # cat gopath/src/github.com/google/syzkaller/perf.cfg { "http": "localhost:50000", "workdir": "/root/gopath/src/github.com/google/syzkaller/workdir", "syzkaller": "/root/gopath/src/github.com/google/syzkaller", "vmlinux": "-", "type": "local", "count": 1, "procs": 160, "cover": false, "dropprivs": false, "enable_syscalls": [ "getpid", "gettid", "perf_event_open", "ioctl$PERF*", "prctl$void", "bpf$*", "sched_yield" ] }