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

From Dmitry Vyukov <dvyukov@google.com>
Newsgroups linux.kernel
Subject Re: [RESEND PATCH 0/5] perf core: Support overwrite ring buffer
Date 2016-03-08 18:50 +0100
Message-ID <ratVF-47w-21@gated-at.bofh.it> (permalink)
References (6 earlier) <rasZA-3on-7@gated-at.bofh.it> <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>
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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.
I've noticed that creation/destruction of namespaces is very slow and
globally serialized. So sometimes it takes tens of seconds for each
worker processes to startup. For perf-related syscalls it should be
"safe" to just run as root. And perf subsystem operation is also
unaffected by namespaces as far as I know, so it should not affect
behavior as well.

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[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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