GNU bug report logs - #46881
28.0.50; pdumper dumping causes way too many syscalls

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Package: emacs;

Reported by: Pip Cet <pipcet <at> gmail.com>

Date: Tue, 2 Mar 2021 20:35:01 UTC

Severity: normal

Found in version 28.0.50

Done: Mattias Engdegård <mattiase <at> acm.org>

Bug is archived. No further changes may be made.

Full log

Message #8 received at 46881 <at> debbugs.gnu.org (full text, mbox):

From: Pip Cet <pipcet <at> gmail.com>
To: 46881 <at> debbugs.gnu.org
Subject: Re: bug#46881: 28.0.50; pdumper dumping causes way too many syscalls
Date: Tue, 2 Mar 2021 20:45:04 +0000

[Message part 1 (text/plain, inline)]
On Tue, Mar 2, 2021 at 8:35 PM Pip Cet <pipcet <at> gmail.com> wrote:
> I've looked into the problem, and it seems easy to solve and worth it
> in terms of debuggability and performance.

Very rough benchmarks, but this seems to be clearly worth it:

Performance:
With patch:
real    0m3.861s
user    0m3.776s
sys    0m0.085s

Without patch:
real    0m7.001s
user    0m4.476s
sys    0m2.511s

Number of syscalls:
With patch: 415442
Without patch: 2028307

> Patch will be attached once this has a bug number.

And here's the patch. Testing would be very appreciated.

I'm unsure about the precise usage of dump_off vs ptrdiff_t here; I
don't think it matters, but suggestions, nitpicks, and comments, on
this or any other aspect, would be very appreciated.

Pip

[0001-Prepare-pdumper-dump-file-in-memory-write-it-in-one-.patch (text/x-patch, attachment)]
This bug report was last modified 4 years and 34 days ago.

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