Re: [PATCH V2] perf: Speed up thread map generation
From: Namhyung Kim
Date: Tue Mar 18 2014 - 10:20:57 EST
On Tue, Mar 18, 2014 at 10:43 PM, Arnaldo Carvalho de Melo
> Em Mon, Mar 17, 2014 at 10:45:49AM +0900, Namhyung Kim escreveu:
>> Hi Don,
>> On Fri, 14 Mar 2014 10:43:44 -0400, Don Zickus wrote:
>> > When trying to capture perf data on a system running spejbb2013,
>> > perf hung for about 15 minutes. This is because it took that
>> > long to gather about 10,000 thread maps and process them.
>> > I don't think a user wants to wait that long.
>> > Instead, recognize that thread maps are roughly equivalent to
>> > pid maps and just quickly copy those instead.
>> > To do this, I synthesize 'fork' events, this eventually calls
>> > thread__fork() and copies the maps over.
>> > The overhead goes from 15 minutes down to about a few seconds.
>> > @@ -416,6 +453,10 @@ int perf_event__synthesize_threads(struct perf_tool *tool,
>> > if (mmap_event == NULL)
>> > goto out_free_comm;
>> > + fork_event = malloc(sizeof(fork_event->fork) + machine->id_hdr_size);
>> > + if (fork_event == NULL)
>> > + goto out_free_mmap;
>> > +
>> > if (machine__is_default_guest(machine))
>> > return 0;
>> Not related to this patch, but this will causes a memory leak..
>> So I think below patch is needed on top (not sure it's also needed for
>> perf_event__synthesize_thread_map() too).
> Good catch, applying it, please next time send it under separate cover,
> i.e. not inside another thread.
Okay. I'll send this kind of patch in a separate thread next time.
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