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[perl #121975] COW speedup lost after e8c6a474

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From:
l.mai@web.de via RT
Date:
February 26, 2016 18:31
Subject:
[perl #121975] COW speedup lost after e8c6a474
Message ID:
rt-4.0.18-10694-1456511461-811.121975-15-0@perl.org
On Thu May 29 02:36:38 2014, demerphq wrote:
> On 29 May 2014 11:11, demerphq <demerphq@gmail.com> wrote:
> 
> >
> > So one option would be to stop using Perl_safesysmalloc_size().
> >
> 
> As this is the easiest to do to prove this is actually the problem I have
> pushed:
> 
> commit ce861ea7963084a7fe72fbb5485e77bb85037b55
> Author: Yves Orton <demerphq@gmail.com>
> Date:   Thu May 29 11:33:56 2014 +0200
> 
>     temporary fix for [perl #121975] COW speedup lost after e8c6a474
> 
>     Disable use of Perl_safesysmalloc_size by default. Only use it when
> PERL_USE_MALLOC_SIZE is defined.
> 
>     Using Perl_safesysmalloc_size() perl cannot tell a deliberately
> preallocated buffer
>     which we probably dont want to COW from a malloc() preallocated buffer
> where we probably
>     dont care. Hopefully this fixes the slowdown observed on some platforms.
> 
> How this affects performance as a whole on the affected platforms I do not
> know. I suspect not much.

Any news? Should this ticket stay open? (It's listed in perl5201delta.)


---
via perlbug:  queue: perl5 status: open
https://rt.perl.org/Ticket/Display.html?id=121975

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