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bug#36597: 27.0.50; rehash hash tables eagerly in pdumper
From: |
Pip Cet |
Subject: |
bug#36597: 27.0.50; rehash hash tables eagerly in pdumper |
Date: |
Sun, 14 Jul 2019 15:01:47 +0000 |
On Sun, Jul 14, 2019 at 2:40 PM Paul Eggert <eggert@cs.ucla.edu> wrote:
> Although I like the simplicity of eager rehashing, I'm not yet sold on the
> performance implications. On my usual (cd lisp && make compile-always)
> benchmark, the patch hurt user+system CPU time performance by 1.5%. Admittedly
> just one benchmark, but still....
Indeed, that's plenty of small Emacs processes not doing very much.
It's not the case we ought to be optimizing for, I think, but the
performance concerns should be taken seriously. One way to avoid the
performance problems entirely is preferred-address loading of hash
dumps, but that has security implications...
> Also, must we expose Vpdumper_hash_tables to Lisp? Surely it'd be better to
> keep
> it private to pdumper.c.
Oops, I agree absolutely. Will remove that.
> I'll CC: to Daniel to see whether he has any insights about improvements in
> this
> area.
Sure; I sent the original email to Daniel, too, of course.
> PS. I ran that benchmark on my home desktop, an Intel Xeon E3-1225 v2 running
> Ubunto 18.04.2. To run it, I rebased your patch and also removed the
> no-longer-used PDUMPER_CHECK_REHASHING macro that my GCC complained about
> (wonder why that didn't happen for you?), resulting in the attached patch
> against current master 8ff09154a29a1151afb2902267ca35f89ebda73c.
Some GCC versions complain about it, some don't, I think.
- bug#36597: 27.0.50; rehash hash tables eagerly in pdumper, Pip Cet, 2019/07/11
- bug#36597: 27.0.50; rehash hash tables eagerly in pdumper, Paul Eggert, 2019/07/14
- bug#36597: 27.0.50; rehash hash tables eagerly in pdumper,
Pip Cet <=
- bug#36597: 27.0.50; rehash hash tables eagerly in pdumper, Paul Eggert, 2019/07/14
- bug#36597: 27.0.50; rehash hash tables eagerly in pdumper, Pip Cet, 2019/07/14
- bug#36597: 27.0.50; rehash hash tables eagerly in pdumper, Pip Cet, 2019/07/15
- bug#36597: 27.0.50; rehash hash tables eagerly in pdumper, Pip Cet, 2019/07/19
- bug#36597: 27.0.50; rehash hash tables eagerly in pdumper, Eli Zaretskii, 2019/07/19
- bug#36597: 27.0.50; rehash hash tables eagerly in pdumper, Pip Cet, 2019/07/20
- bug#36597: 27.0.50; rehash hash tables eagerly in pdumper, Paul Eggert, 2019/07/20
- bug#36597: 27.0.50; rehash hash tables eagerly in pdumper, Pip Cet, 2019/07/21
- bug#36597: 27.0.50; rehash hash tables eagerly in pdumper, Paul Eggert, 2019/07/21
- bug#36597: 27.0.50; rehash hash tables eagerly in pdumper, Pip Cet, 2019/07/21