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Re: [PATCH/RFC v2] perf core: Allow setting up max frame stack depth via sysctl

From Arnaldo Carvalho de Melo <acme@kernel.org>
Newsgroups linux.kernel
Subject Re: [PATCH/RFC v2] perf core: Allow setting up max frame stack depth via sysctl
Date 2016-04-25 18:20 +0200
Message-ID <rrRoU-mn-35@gated-at.bofh.it> (permalink)
References <rq96y-799-13@gated-at.bofh.it> <rq9pU-7AD-15@gated-at.bofh.it> <rqQlb-88k-3@gated-at.bofh.it> <rqRqX-Lm-23@gated-at.bofh.it> <rqRAD-Pr-47@gated-at.bofh.it>
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Em Fri, Apr 22, 2016 at 03:18:08PM -0700, Alexei Starovoitov escreveu:
> On Fri, Apr 22, 2016 at 04:05:31PM -0600, David Ahern wrote:
> > On 4/22/16 2:52 PM, Arnaldo Carvalho de Melo wrote:
> > >+int sysctl_perf_event_max_stack __read_mostly = PERF_MAX_STACK_DEPTH;
> > >+
> > >+static size_t perf_callchain_entry__sizeof(void)
> > >+{
> > >+	return sizeof(struct perf_callchain_entry) +
> > >+	       sizeof(__u64) * sysctl_perf_event_max_stack;
> > >+}
> > >+

> > To Alexei's comment, a max_stack of 0 still has a non-zero alloc size so
> > that should be ok.

> > >  static DEFINE_PER_CPU(int, callchain_recursion[PERF_NR_CONTEXTS]);
> > >  static atomic_t nr_callchain_events;
> > >  static DEFINE_MUTEX(callchain_mutex);
> > >@@ -73,7 +81,7 @@ static int alloc_callchain_buffers(void)
> > >  	if (!entries)
> > >  		return -ENOMEM;

> > >-	size = sizeof(struct perf_callchain_entry) * PERF_NR_CONTEXTS;
> > >+	size = perf_callchain_entry__sizeof() * PERF_NR_CONTEXTS;

> > >  	for_each_possible_cpu(cpu) {
> > >  		entries->cpu_entries[cpu] = kmalloc_node(size, GFP_KERNEL,
 
> right... and looking into it further, realized that the patch is broken,
> since get_callchain_entry() is doing:
>   return &entries->cpu_entries[cpu][*rctx];
> whereas it should be dynamic offset based on sysctl_perf_event_max_stack*8
> So definitely needs another respin.

Huh? Can you elaborate a bit more?

Are you saying this is a bug introduced by this patch or something
pre-existing?

- Arnaldo

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Thread

[PATCH/RFC] perf core: Allow setting up max frame stack depth via  sysctl Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-04-21 00:50 +0200
  Re: [PATCH/RFC] perf core: Allow setting up max frame stack depth  via sysctl Alexei Starovoitov <alexei.starovoitov@gmail.com> - 2016-04-21 01:10 +0200
    [PATCH/RFC v2] perf core: Allow setting up max frame stack depth via  sysctl Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-04-22 23:00 +0200
      Re: [PATCH/RFC v2] perf core: Allow setting up max frame stack depth  via sysctl Alexei Starovoitov <alexei.starovoitov@gmail.com> - 2016-04-22 23:40 +0200
      Re: [PATCH/RFC v2] perf core: Allow setting up max frame stack depth  via sysctl David Ahern <dsahern@gmail.com> - 2016-04-23 00:10 +0200
        Re: [PATCH/RFC v2] perf core: Allow setting up max frame stack depth  via sysctl Alexei Starovoitov <alexei.starovoitov@gmail.com> - 2016-04-23 00:20 +0200
          Re: [PATCH/RFC v2] perf core: Allow setting up max frame stack depth  via sysctl Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-04-25 18:20 +0200
            Re: [PATCH/RFC v2] perf core: Allow setting up max frame stack depth  via sysctl Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-04-25 18:30 +0200
              Re: [PATCH/RFC v2] perf core: Allow setting up max frame stack depth  via sysctl Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-04-25 21:30 +0200
                Re: [PATCH/RFC v2] perf core: Allow setting up max frame stack depth  via sysctl Alexei Starovoitov <alexei.starovoitov@gmail.com> - 2016-04-25 22:10 +0200
                Re: [PATCH/RFC v2] perf core: Allow setting up max frame stack depth  via sysctl Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-04-25 22:20 +0200
                Re: [PATCH/RFC v2] perf core: Allow setting up max frame stack depth  via sysctl Alexei Starovoitov <alexei.starovoitov@gmail.com> - 2016-04-26 00:10 +0200
                Re: [PATCH/RFC v2] perf core: Allow setting up max frame stack depth  via sysctl Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-04-26 01:50 +0200
                Re: [PATCH/RFC v2] perf core: Allow setting up max frame stack depth  via sysctl Alexei Starovoitov <alexei.starovoitov@gmail.com> - 2016-04-26 02:10 +0200
                [PATCH/RFC v3] perf core: Allow setting up max frame stack depth via  sysctl Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-04-26 02:30 +0200
                Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth  via sysctl Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-04-26 02:50 +0200
                Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth  via sysctl Brendan Gregg <brendan.d.gregg@gmail.com> - 2016-04-26 03:00 +0200
                Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth  via sysctl Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-04-26 18:40 +0200
                Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth  via sysctl David Ahern <dsahern@gmail.com> - 2016-04-26 18:50 +0200
                Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth  via sysctl Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-04-27 15:30 +0200
                Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth  via sysctl Brendan Gregg <brendan.d.gregg@gmail.com> - 2016-04-26 22:10 +0200
                Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth  via sysctl Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-04-26 23:10 +0200
                Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth  via sysctl Peter Zijlstra <peterz@infradead.org> - 2016-04-27 00:00 +0200
                Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth  via sysctl Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-04-27 15:00 +0200
                Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth  via sysctl Brendan Gregg <brendan.d.gregg@gmail.com> - 2016-04-27 00:00 +0200
                Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth  via sysctl Peter Zijlstra <peterz@infradead.org> - 2016-04-27 00:20 +0200
                Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth  via sysctl Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-04-27 15:00 +0200
                Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth  via sysctl Alexei Starovoitov <alexei.starovoitov@gmail.com> - 2016-04-26 02:50 +0200
                Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth  via sysctl Frederic Weisbecker <fweisbec@gmail.com> - 2016-04-27 00:00 +0200
                Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth  via sysctl Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-04-27 15:00 +0200
                Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth  via sysctl Frederic Weisbecker <fweisbec@gmail.com> - 2016-04-27 18:10 +0200
                Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth  via sysctl David Ahern <dsahern@gmail.com> - 2016-04-27 18:30 +0200
                [tip:perf/core] perf core: Allow setting up max frame stack depth  via sysctl tip-bot for Arnaldo Carvalho de Melo <tipbot@zytor.com> - 2016-04-27 17:50 +0200
  Re: [PATCH/RFC] perf core: Allow setting up max frame stack depth via  sysctl David Ahern <dsahern@gmail.com> - 2016-04-21 01:20 +0200
    Re: [PATCH/RFC] perf core: Allow setting up max frame stack depth  via sysctl Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-04-21 02:20 +0200
  Re: [PATCH/RFC] perf core: Allow setting up max frame stack depth  via sysctl Peter Zijlstra <peterz@infradead.org> - 2016-04-21 13:00 +0200
    Re: [PATCH/RFC] perf core: Allow setting up max frame stack depth  via sysctl Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-04-21 17:20 +0200
      Re: [PATCH/RFC] perf core: Allow setting up max frame stack depth  via sysctl Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-04-21 17:50 +0200

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