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bug#46881: 28.0.50; pdumper dumping causes way too many syscalls
From: |
Eli Zaretskii |
Subject: |
bug#46881: 28.0.50; pdumper dumping causes way too many syscalls |
Date: |
Fri, 05 Mar 2021 14:06:55 +0200 |
> From: Pip Cet <pipcet@gmail.com>
> Date: Fri, 5 Mar 2021 09:54:32 +0000
> Cc: Daniel Colascione <dancol@dancol.org>, eggert@cs.ucla.edu,
> 46881@debbugs.gnu.org
>
> My patch:
>
> real 0m1.988s
> user 0m1.916s
> sys 0m0.073s
>
> fwrite-based patch:
>
> real 0m3.576s
> user 0m2.571s
> sys 0m1.006s
30% slowdown and 1.5 sec absolute time difference doesn't sound bad
enough to me to justify a homemade solution. I say let's go with
stdio.
> > > Also, we're not currently using fseek-and-write anywhere in Emacs.
> >
> > I don't see why this would be important.
>
> Because the stream returned by emacs_fopen might not be generally seekable?
I don't see how that could happen.
> > Since we open the file in
> > binary mode, fseek should work correctly even on non-Posix systems.
>
> I guess I should have used emacs_fopen :-)
Yes, of course. Especially as with fopen there are problems with
non-ASCII file names on MS-Windows.
> By preparing the data in memory and writing it in one go, which
> doesn't require any of the major complications of implementing
> buffered streams.
There are no complications I can see, not in our sources. (And you
don't actually write it in one go anyway, see emacs_full_write.)
So let's go with the stdio solution, please.
- bug#46881: 28.0.50; pdumper dumping causes way too many syscalls, (continued)
- bug#46881: 28.0.50; pdumper dumping causes way too many syscalls, Daniel Colascione, 2021/03/04
- bug#46881: 28.0.50; pdumper dumping causes way too many syscalls, Pip Cet, 2021/03/04
- bug#46881: 28.0.50; pdumper dumping causes way too many syscalls, Eli Zaretskii, 2021/03/05
- bug#46881: 28.0.50; pdumper dumping causes way too many syscalls, Pip Cet, 2021/03/05
- bug#46881: 28.0.50; pdumper dumping causes way too many syscalls, Eli Zaretskii, 2021/03/05
- bug#46881: 28.0.50; pdumper dumping causes way too many syscalls, Pip Cet, 2021/03/05
- bug#46881: 28.0.50; pdumper dumping causes way too many syscalls, Andrea Corallo, 2021/03/05
- bug#46881: 28.0.50; pdumper dumping causes way too many syscalls,
Eli Zaretskii <=
- bug#46881: 28.0.50; pdumper dumping causes way too many syscalls, Lars Ingebrigtsen, 2021/03/05
- bug#46881: 28.0.50; pdumper dumping causes way too many syscalls, Eli Zaretskii, 2021/03/05
- bug#46881: 28.0.50; pdumper dumping causes way too many syscalls, Pip Cet, 2021/03/05
- bug#46881: 28.0.50; pdumper dumping causes way too many syscalls, Pip Cet, 2021/03/05
- bug#46881: 28.0.50; pdumper dumping causes way too many syscalls, Daniel Colascione, 2021/03/05
- bug#46881: 28.0.50; pdumper dumping causes way too many syscalls, Eli Zaretskii, 2021/03/05
- bug#46881: 28.0.50; pdumper dumping causes way too many syscalls, Pip Cet, 2021/03/05
- bug#46881: 28.0.50; pdumper dumping causes way too many syscalls, Andreas Schwab, 2021/03/05
- bug#46881: 28.0.50; pdumper dumping causes way too many syscalls, Pip Cet, 2021/03/05