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Re: [perl #129802] COW performance problems with regexps

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From:
Niko Tyni
Date:
November 4, 2016 10:20
Subject:
Re: [perl #129802] COW performance problems with regexps
Message ID:
20161104102011.q63a7gapmcudmxje@estella.local.invalid
On Sun, Oct 30, 2016 at 11:29:10AM +0100, demerphq wrote:

> commit fe546b38f5a7481954f2f933acf85267578058b3
> Author: Yves Orton <demerphq@gmail.com>
> Date:   Sun Oct 30 11:02:57 2016 +0100
> 
>     fix #129802: sv_grow: remove the overallocation for COW exemption
> for powers of 2

> commit 7fdc4f5848180e5ae502e30ea783733d0da04086
> Author: Yves Orton <demerphq@gmail.com>
> Date:   Sun Oct 30 10:56:36 2016 +0100
> 
>     fix perl #129802 - overallocate in concat to ensure we can COW

> The first is potentially controversial. So it might get reverted. But
> I consider this ticket closed/fixed.

Many thanks for your work. Just in case you didn't notice, there was
earlier correspondence on this ticket including a comment from Dave with
pretty much the same conclusions.

As this seems to be a performance regression in 5.20 or so (and was
originally reported to Debian as one), is the fix something that could
be considered for the maint-* branches?
-- 
Niko Tyni   ntyni@debian.org

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