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

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From:
demerphq
Date:
November 4, 2016 14:41
Subject:
Re: [perl #129802] COW performance problems with regexps
Message ID:
CANgJU+VGZbJY9QBW8zKwkS1qD-npn7-9MCXMkZbeS-rhb=WYHg@mail.gmail.com
On 4 November 2016 at 11:20, Niko Tyni <ntyni@debian.org> wrote:
> 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.

You are welcome. It is always a pleasure working with you Debian folks.

> 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?

Just to repeat what I said in reply to Tony, unless the power-of-2
issue gets reverted I would assume that these patches are fine for
backport.

Yves

-- 
perl -Mre=debug -e "/just|another|perl|hacker/"

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