Re: [PATCH V2] perf: Speed up thread map generation

[Namhyung Kim]

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.

[SNIP]
> @@ -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).