From: Junio C Hamano <gitster@pobox.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: "Erik Faye-Lund" <kusmabite@gmail.com>,
"Junio C Hamano" <gitster@pobox.com>,
git@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Peter Zijlstra" <a.p.zijlstra@chello.nl>,
"Arnaldo Carvalho de Melo" <acme@redhat.com>,
"Frédéric Weisbecker" <fweisbec@gmail.com>,
"Pekka Enberg" <penberg@cs.helsinki.fi>
Subject: Re: [PATCH] git gc: Speed it up by 18% via faster hash comparisons
Date: Thu, 28 Apr 2011 13:20:54 -0700 [thread overview]
Message-ID: <7v8vuu3z6h.fsf@alter.siamese.dyndns.org> (raw)
In-Reply-To: <20110428101902.GA17257@elte.hu> (Ingo Molnar's message of "Thu, 28 Apr 2011 12:19:02 +0200")
Ingo Molnar <mingo@elte.hu> writes:
> In any case, i'll retract the null case as it really isnt called that often in
> the tests i've done - updated patch below - it simply falls back on to hashcmp.
>
> Thanks,
>
> Ingo
>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Thanks, will queue this version.
> diff --git a/cache.h b/cache.h
> index 2674f4c..39fa9cd 100644
> --- a/cache.h
> +++ b/cache.h
> @@ -675,14 +675,24 @@ extern char *sha1_pack_name(const unsigned char *sha1);
> extern char *sha1_pack_index_name(const unsigned char *sha1);
> extern const char *find_unique_abbrev(const unsigned char *sha1, int);
> extern const unsigned char null_sha1[20];
> -static inline int is_null_sha1(const unsigned char *sha1)
> +
> +static inline int hashcmp(const unsigned char *sha1, const unsigned char *sha2)
> {
> - return !memcmp(sha1, null_sha1, 20);
> + int i;
> +
> + for (i = 0; i < 20; i++, sha1++, sha2++) {
> + if (*sha1 != *sha2)
> + return *sha1 - *sha2;
> + }
> +
> + return 0;
> }
> -static inline int hashcmp(const unsigned char *sha1, const unsigned char *sha2)
> +
> +static inline int is_null_sha1(const unsigned char *sha1)
> {
> - return memcmp(sha1, sha2, 20);
> + return !hashcmp(sha1, null_sha1);
> }
> +
> static inline void hashcpy(unsigned char *sha_dst, const unsigned char *sha_src)
> {
> memcpy(sha_dst, sha_src, 20);
next prev parent reply other threads:[~2011-04-28 20:21 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-27 22:51 [PATCH] git gc: Speed it up by 18% via faster hash comparisons Ingo Molnar
2011-04-27 23:10 ` Ingo Molnar
2011-04-27 23:18 ` Jonathan Nieder
2011-04-28 6:36 ` Ingo Molnar
2011-04-28 9:31 ` Jonathan Nieder
2011-04-28 10:36 ` Ingo Molnar
2011-04-28 9:32 ` Dmitry Potapov
2011-04-27 23:32 ` Junio C Hamano
2011-04-28 0:35 ` Ralf Baechle
2011-04-28 8:18 ` Bernhard R. Link
2011-04-28 9:42 ` Andreas Ericsson
2011-04-28 9:55 ` Erik Faye-Lund
2011-04-28 20:19 ` H. Peter Anvin
2011-04-28 6:27 ` Ingo Molnar
2011-04-28 9:17 ` Erik Faye-Lund
2011-04-28 9:33 ` Ingo Molnar
2011-04-28 9:37 ` Ingo Molnar
2011-04-28 9:50 ` Erik Faye-Lund
2011-04-28 10:10 ` Pekka Enberg
2011-04-28 10:19 ` Erik Faye-Lund
2011-04-28 10:30 ` Pekka Enberg
2011-04-28 11:59 ` Erik Faye-Lund
2011-04-28 12:12 ` Pekka Enberg
2011-04-28 12:36 ` Jonathan Nieder
2011-04-28 12:40 ` Erik Faye-Lund
2011-04-28 13:37 ` Ingo Molnar
2011-04-28 15:14 ` Ingo Molnar
2011-04-28 16:00 ` Erik Faye-Lund
2011-04-28 20:32 ` Ingo Molnar
2011-04-29 7:05 ` Alex Riesen
2011-04-29 16:24 ` H. Peter Anvin
2011-04-28 12:16 ` Tor Arntsen
2011-04-28 20:23 ` H. Peter Anvin
2011-04-28 12:17 ` Andreas Ericsson
2011-04-28 12:28 ` Erik Faye-Lund
2011-04-28 10:19 ` Ingo Molnar
2011-04-28 12:02 ` Nguyen Thai Ngoc Duy
2011-04-28 12:18 ` Erik Faye-Lund
2011-04-28 20:20 ` Junio C Hamano [this message]
2011-04-28 16:36 ` Dmitry Potapov
2011-04-28 8:52 ` Dmitry Potapov
2011-04-28 9:11 ` Ingo Molnar
2011-04-28 9:31 ` Dmitry Potapov
2011-04-28 9:44 ` Ingo Molnar
2011-04-28 9:38 ` Ingo Molnar
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: http://vger.kernel.org/majordomo-info.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=7v8vuu3z6h.fsf@alter.siamese.dyndns.org \
--to=gitster@pobox.com \
--cc=a.p.zijlstra@chello.nl \
--cc=acme@redhat.com \
--cc=fweisbec@gmail.com \
--cc=git@vger.kernel.org \
--cc=hpa@zytor.com \
--cc=kusmabite@gmail.com \
--cc=mingo@elte.hu \
--cc=penberg@cs.helsinki.fi \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).