From: Stefan Monnier <monnier@IRO.UMontreal.CA>
To: Paul Eggert <eggert@cs.ucla.edu>
Cc: emacs-devel@gnu.org
Subject: Re: Lisp_Marker size on 32bit systems
Date: Fri, 07 Sep 2018 08:16:51 -0400 [thread overview]
Message-ID: <jwv36ulsdut.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <06d01a4b-9d98-df5b-be8a-aeda449acad7@cs.ucla.edu> (Paul Eggert's message of "Fri, 7 Sep 2018 00:15:57 -0700")
> Although the first attached patch shrinks sizeof (struct Lisp_Maker) from 32
> to 24 bytes on x86 as requested, allocate_pseudovector still *allocates* 32
> bytes for the struct, as it rounds the size up to the next multiple of
> alignof (max_align_t), which is 16 on x86. It's not hard to change that to
> 8 (please see 2nd attached patch) but this causes a 20% CPU performance hit
> (!) to 'make compile-always' on my platform (AMD Phenom II X4 910e circa
> 2010, Fedora 28 x86-64, gcc -m32 -march=native), so I didn't install and
> can't recommend the 2nd attached patch.
Where does this 20% slow down come from?
Stefan
next prev parent reply other threads:[~2018-09-07 12:16 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-06 0:41 Lisp_Marker size on 32bit systems Stefan Monnier
2018-09-06 6:51 ` Paul Eggert
2018-09-06 12:17 ` Stefan Monnier
2018-09-07 7:15 ` Paul Eggert
2018-09-07 8:05 ` Eli Zaretskii
2018-09-07 13:45 ` Paul Eggert
2018-09-07 14:12 ` GDB and compiler-operations (was: Lisp_Marker size on 32bit systems) Stefan Monnier
2018-09-07 14:23 ` Eli Zaretskii
2018-09-07 15:16 ` GDB and compiler-operations Andreas Schwab
2018-09-07 15:48 ` GDB and compiler-operations (was: Lisp_Marker size on 32bit systems) Paul Eggert
2018-09-07 15:58 ` GDB and compiler-operations Stefan Monnier
2018-09-07 17:11 ` Eli Zaretskii
2018-09-07 17:15 ` Paul Eggert
2018-09-07 19:59 ` Tom Tromey
2018-09-07 14:19 ` Lisp_Marker size on 32bit systems Eli Zaretskii
2018-09-07 16:27 ` Paul Eggert
2018-09-07 17:16 ` Eli Zaretskii
2018-09-07 18:13 ` Paul Eggert
2018-09-07 18:32 ` Eli Zaretskii
2018-09-07 19:05 ` Paul Eggert
2018-09-07 19:22 ` Eli Zaretskii
2018-09-07 12:16 ` Stefan Monnier [this message]
2018-09-07 19:04 ` Paul Eggert
2018-09-07 19:45 ` Stefan Monnier
2018-09-07 21:03 ` Paul Eggert
2018-09-08 1:54 ` Stefan Monnier
2018-09-08 3:04 ` Paul Eggert
2018-09-08 3:10 ` Stefan Monnier
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