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Re: [v3] libstdc++/24469

From: Paolo Carlini <pcarlini at suse dot de>
To: Richard Guenther <richard dot guenther at gmail dot com>
Cc: Benjamin Kosnik <bkoz at redhat dot com>, libstdc++ at gcc dot gnu dot org, gcc-patches at gcc dot gnu dot org
Date: Thu, 16 Mar 2006 17:20:33 +0100
Subject: Re: [v3] libstdc++/24469
References: <20060316014442.e21a6fff.bkoz@redhat.com> <84fc9c000603160157r6fc3bab8h4acd96176b7bfb90@mail.gmail.com> <44198CC5.1070605@suse.de> <84fc9c000603160815q6c6687c1y132f2203c613c351@mail.gmail.com>

Richard Guenther wrote:

I have also to study again this long standing issue vs the brancd new performance improvements contributed by Boreham and Bridges, but in fact, in the ""old"" code the issue was rather simple: _M_used, and only _M_used, could be changed simultaneously by different threads. Thus, a possible fix could involve using __exchange_and_add/__atomic_add on _M_used.

I do not see this concurrent updating of _M_used.

Did you study the PR? Sorry, Richard, but this "assault" of yours in the occasion of the patch, with no previous discussions and participation to the development of the code, in some areas definitely rather subtle, seems to me rather weird and naive.

Paolo.

Follow-Ups:
- Re: [v3] libstdc++/24469
  - From: Richard Guenther

References:
- [v3] libstdc++/24469
  - From: Benjamin Kosnik
- Re: [v3] libstdc++/24469
  - From: Richard Guenther
- Re: [v3] libstdc++/24469
  - From: Paolo Carlini
- Re: [v3] libstdc++/24469
  - From: Richard Guenther

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