lkml.org 
[lkml]   [2012]   [Aug]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] perf: do not flush maps on COMM for perf report

* Luigi Semenzato <semenzato@chromium.org> wrote:

> This fixes a long-standing bug caused by the lack of separate
> COMM and EXEC record types, which makes "perf report" lose
> track of symbols when a process renames itself.
>
> With this fix (suggested by Stephane Eranian), a COMM (rename)
> no longer flushes the maps, which is the correct behavior.
> An EXEC also no longer flushes the maps, but this doesn't
> matter because as new mappings are created (for the executable
> and the libraries) the old mappings are automatically removed.
> This is not by accident: the functionality is necessary because
> DLLs can be explicitly loaded at any time with dlopen(),
> possibly on top of existing text, so "perf report" handles
> correctly the clobbering of new mappings on top of old ones.
>
> An alternative patch (which I proposed earlier) would be to
> introduce a separate PERF_RECORD_EXEC type, but it is a much
> larger change (about 300 lines) and is not necessary.

It would be nice to add that too - we already have FORK/EXIT,
this seems like a natural extension.

Thanks,

Ingo


\
 
 \ /
  Last update: 2012-08-22 10:01    [from the cache]
©2003-2011 Jasper Spaans