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From: Tom Tromey <tromey@redhat.com>
To: Markus Alber <markus@hyperion-imrt.org>
Cc: Michael Snyder <msnyder@vmware.com>, <gdb@sourceware.org>
Subject: Re: performance of multithreading gets gradually worse under gdb
Date: Thu, 03 Feb 2011 20:57:00 -0000	[thread overview]
Message-ID: <m3lj1wet07.fsf@fleche.redhat.com> (raw)
In-Reply-To: <0e69c90ce85e34a24a5bcef1ce391aae@hyperion-imrt.org> (Markus	Alber's message of "Thu, 03 Feb 2011 08:02:57 +0100")

>>>>> "Markus" == Markus Alber <markus@hyperion-imrt.org> writes:

Markus> See the attached file. It shows a similar behaviour, although it only
Markus> allocates 8kB per iteration.
Markus> You have to wait some time before this happens.

Thanks.

I changed 1<<24 to 1<<15, to spare my underpowered machine, and ran gdb
under massif.

This part is interesting:

->20.78% (2,954,016B) 0x8253683: regcache_xmalloc_1 (regcache.c:232)
| ->20.78% (2,954,016B) 0x8253F85: get_thread_arch_regcache (regcache.c:463)
|   ->20.78% (2,954,016B) 0x82540B5: get_thread_regcache (regcache.c:488)
|     ->20.78% (2,954,016B) 0x81D1579: i386_linux_resume (i386-linux-nat.c:861)
|     | ->20.78% (2,954,016B) 0x81D7D32: linux_nat_resume (linux-nat.c:1983)


I debugged gdb a little and it does indeed seem to be leaking here.

I don't understand why registers_changed_ptid unconditionally clears
current_regcache.  I suspect that may be the source of the problem.

Perhaps someone who knows this code better could take a look.

Tom


  parent reply	other threads:[~2011-02-03 20:57 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-02 20:16 Markus Alber
2011-02-02 20:28 ` Michael Snyder
     [not found]   ` <76bccf1875854ebc69b6a892fb84a976@hyperion-imrt.org>
2011-02-02 21:43     ` Michael Snyder
2011-02-03  7:03       ` Markus Alber
2011-02-03 20:26         ` Michael Snyder
2011-02-03 20:52           ` Markus Alber
2011-02-03 20:57         ` Tom Tromey [this message]
2011-02-03 21:00           ` Tom Tromey
2011-02-03 21:40           ` Ulrich Weigand
2011-02-03 22:04             ` Tom Tromey
2011-02-04 13:49               ` Ulrich Weigand
2011-02-04 14:55             ` Pedro Alves
2011-02-04 15:13               ` Ulrich Weigand
2011-02-04 15:26               ` Tom Tromey
2011-02-04 15:56                 ` Pedro Alves
     [not found]                 ` <201102041555.52179.pedro__21913.9744448059$1296834976$gmane$org@codesourcery.com>
2011-02-04 17:02                   ` Tom Tromey
2011-02-05  9:34                     ` Markus Alber
2011-02-07 14:05                     ` Markus Alber

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