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

From Ingo Molnar <mingo@kernel.org>
Newsgroups linux.kernel
Subject Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer
Date 2016-03-08 18:50 +0100
Message-ID <ratVI-47w-79@gated-at.bofh.it> (permalink)
References (5 earlier) <ratiV-3LD-7@gated-at.bofh.it> <ratCi-3TL-11@gated-at.bofh.it> <ratCj-3TL-29@gated-at.bofh.it> <ratLZ-40W-37@gated-at.bofh.it> <ratVF-47w-21@gated-at.bofh.it>
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* Dmitry Vyukov <dvyukov@google.com> wrote:

> On Tue, Mar 8, 2016 at 6:37 PM, Ingo Molnar <mingo@kernel.org> wrote:
> >
> > * Dmitry Vyukov <dvyukov@google.com> wrote:
> >
> >> > fomalhaut:~/go/src/github.com/google/syzkaller> ps aux | grep -i syz
> >> > mingo      1374  0.0  0.0 118476  2376 pts/2    S+   18:23   0:00 grep --color=auto -i syz
> >> >
> >> > and with no kernel messages in dmesg - and with a fully functional system.
> >> >
> >> > I'm running the 16-task load on a 120 CPU system - should I increase it to 120?
> >> > Does the code expect to saturate the system?
> >>
> >> No, it does not expect to saturate the system. Set "procs" to 480, or
> >> something like that.
> >
> > Does not seem to help much:
> >
> > fomalhaut:~> vmstat 10
> > procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
> >  r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
> >
> >  1  0      0 257465904 219940 4736092    0    0     0   102 16022 4396  0  1 99  0  0
> >  2  0      0 257452144 220496 4755052    0    0     2  3649 14286 4627  0  1 99  0  0
> >  2  0      0 257473408 221188 4770824    0    0    15  1898 17175 4474  0  1 99  0  0
> >
> > Only around 1% system utilization. Should I go for 1,000 or more? :)
> >
> > Peter, do you experience with running syz-kaller on larger CPU count Intel
> > systems?
> 
> 
> Try to set "dropprivs": false in config.

Things got a lot more lively after that!

But most of the overhead seems to come from systemd trying to dump core or 
something like that:

 85872 mingo     20   0   34712   3016   2656 S   4.6  0.0   0:00.14 systemd-coredum                                                                                                  
 85440 mingo     20   0   34712   3028   2664 S   4.2  0.0   0:00.13 systemd-coredum                                                                                                  
 85751 mingo     20   0   34712   3076   2716 S   4.2  0.0   0:00.13 systemd-coredum                                                                                                  
 85840 mingo     20   0   34712   2988   2624 S   4.2  0.0   0:00.13 systemd-coredum                                                                                                  
 85861 mingo     20   0   34712   3080   2720 S   4.2  0.0   0:00.13 systemd-coredum                                                                                                  
 85954 mingo     20   0   34712   3028   2664 S   4.2  0.0   0:00.13 systemd-coredum          

and I have:

 fomalhaut:~/go/src/github.com/google/syzkaller> ulimit -c
 0

weird ... Has any of you seen such behavior?

Thanks,

	Ingo

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Thread

[RESEND PATCH 0/5] perf core: Support overwrite ring buffer Wang Nan <wangnan0@huawei.com> - 2016-03-07 05:00 +0100
  [RESEND PATCH 5/5] perf core: Reduce perf event output overhead by new overflow handler Wang Nan <wangnan0@huawei.com> - 2016-03-07 05:00 +0100
  [RESEND PATCH 4/5] perf core: Add backward attribute to perf event Wang Nan <wangnan0@huawei.com> - 2016-03-07 05:00 +0100
  [RESEND PATCH 3/5] perf core: Prepare writing into ring buffer from end Wang Nan <wangnan0@huawei.com> - 2016-03-07 05:00 +0100
  Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Peter Zijlstra <peterz@infradead.org> - 2016-03-08 14:50 +0100
    Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Ingo Molnar <mingo@kernel.org> - 2016-03-08 14:50 +0100
      Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Peter Zijlstra <peterz@infradead.org> - 2016-03-08 15:00 +0100
        Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Ingo Molnar <mingo@kernel.org> - 2016-03-08 16:30 +0100
          Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Dmitry Vyukov <dvyukov@google.com> - 2016-03-08 16:40 +0100
            Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Ingo Molnar <mingo@kernel.org> - 2016-03-08 17:00 +0100
              Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Dmitry Vyukov <dvyukov@google.com> - 2016-03-08 17:20 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Ingo Molnar <mingo@kernel.org> - 2016-03-08 17:30 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Dmitry Vyukov <dvyukov@google.com> - 2016-03-08 17:40 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Peter Zijlstra <peterz@infradead.org> - 2016-03-08 17:40 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Ingo Molnar <mingo@kernel.org> - 2016-03-08 17:50 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Ingo Molnar <mingo@kernel.org> - 2016-03-08 17:50 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Dmitry Vyukov <dvyukov@google.com> - 2016-03-08 18:10 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Ingo Molnar <mingo@kernel.org> - 2016-03-08 18:30 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Dmitry Vyukov <dvyukov@google.com> - 2016-03-08 18:30 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Ingo Molnar <mingo@kernel.org> - 2016-03-08 18:40 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Dmitry Vyukov <dvyukov@google.com> - 2016-03-08 18:50 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Ingo Molnar <mingo@kernel.org> - 2016-03-08 18:50 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Peter Zijlstra <peterz@infradead.org> - 2016-03-08 19:00 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Ingo Molnar <mingo@kernel.org> - 2016-03-08 19:00 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Ingo Molnar <mingo@kernel.org> - 2016-03-08 19:10 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Ingo Molnar <mingo@kernel.org> - 2016-03-08 19:30 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Ingo Molnar <mingo@kernel.org> - 2016-03-08 19:40 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Dmitry Vyukov <dvyukov@google.com> - 2016-03-08 19:00 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Peter Zijlstra <peterz@infradead.org> - 2016-03-08 19:00 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Peter Zijlstra <peterz@infradead.org> - 2016-03-08 17:40 +0100
              Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Borislav Petkov <bp@alien8.de> - 2016-03-09 12:00 +0100
                Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Dmitry Vyukov <dvyukov@google.com> - 2016-03-09 12:30 +0100
        Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Jiri Olsa <jolsa@redhat.com> - 2016-03-08 21:00 +0100
          Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Peter Zijlstra <peterz@infradead.org> - 2016-03-08 21:10 +0100
            Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Jiri Olsa <jolsa@redhat.com> - 2016-03-08 21:50 +0100
              Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer Peter Zijlstra <peterz@infradead.org> - 2016-03-08 22:10 +0100

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