From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
To: Jeff King <peff@peff.net>
Cc: git@vger.kernel.org, "Junio C Hamano" <gitster@pobox.com>,
"Benjamin Kramer" <benny.kra@googlemail.com>,
"René Scharfe" <l.s.r@web.de>
Subject: Re: [PATCH v4 3/3] regex: use regexec_buf()
Date: Sun, 25 Sep 2016 16:01:54 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.20.1609251600120.129229@virtualbox> (raw)
In-Reply-To: <20160921220310.5wk76qdsjyhvstk4@sigill.intra.peff.net>
Hi Peff,
On Wed, 21 Sep 2016, Jeff King wrote:
> On Wed, Sep 21, 2016 at 08:24:14PM +0200, Johannes Schindelin wrote:
>
> > The new regexec_buf() function operates on buffers with an explicitly
> > specified length, rather than NUL-terminated strings.
> >
> > We need to use this function whenever the buffer we want to pass to
> > regexec() may have been mmap()ed (and is hence not NUL-terminated).
> >
> > Note: the original motivation for this patch was to fix a bug where
> > `git diff -G <regex>` would crash. This patch converts more callers,
> > though, some of which explicitly allocated and constructed
> > NUL-terminated strings (or worse: modified read-only buffers to insert
> > NULs).
>
> Nice. I probably would have split these into their own patch, but I
> think it is OK here.
True. I guess I was a little lazy...
> > @@ -228,18 +227,16 @@ static long ff_regexp(const char *line, long len,
> > len--;
> > }
> >
> > - line_buffer = xstrndup(line, len); /* make NUL terminated */
> > -
>
> Nice to see this one going away in particular, since it's called quite a
> lot. According to perf, "git log -p" on git.git drops about 1.5 million
> malloc calls (about 9% of the total). And here are best-of-five results
> for that same command:
>
> [before]
> real 0m14.676s
> user 0m13.988s
> sys 0m0.676s
>
> [after]
> real 0m14.394s
> user 0m13.624s
> sys 0m0.760s
>
> Not a _huge_ improvement, but more significant than the run-to-run
> noise.
Oh, that's nice! As you guessed, my aim was not to improve performance,
but it is a pretty side effect...
Thanks for testing!
Dscho
next prev parent reply other threads:[~2016-09-25 14:02 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-05 15:44 [PATCH 0/3] Fix a segfault caused by regexec() being called on mmap()ed data Johannes Schindelin
2016-09-05 15:45 ` [PATCH 1/3] Demonstrate a problem: our pickaxe code assumes NUL-terminated buffers Johannes Schindelin
2016-09-06 18:43 ` Jeff King
2016-09-08 7:53 ` Johannes Schindelin
2016-09-05 15:45 ` [PATCH 2/3] diff_populate_filespec: NUL-terminate buffers Johannes Schindelin
2016-09-06 7:06 ` Jeff King
2016-09-06 16:02 ` Johannes Schindelin
2016-09-06 18:41 ` Jeff King
2016-09-07 18:31 ` Junio C Hamano
2016-09-08 7:52 ` Johannes Schindelin
2016-09-08 7:49 ` Johannes Schindelin
2016-09-08 8:22 ` Jeff King
2016-09-08 16:57 ` Junio C Hamano
2016-09-08 18:22 ` Johannes Schindelin
2016-09-08 18:48 ` Jeff King
2016-09-05 15:45 ` [PATCH 3/3] diff_grep: add assertions verifying that the buffers are NUL-terminated Johannes Schindelin
2016-09-06 7:08 ` Jeff King
2016-09-06 16:04 ` Johannes Schindelin
2016-09-05 19:10 ` [PATCH 0/3] Fix a segfault caused by regexec() being called on mmap()ed data Junio C Hamano
2016-09-06 7:12 ` Jeff King
2016-09-06 14:06 ` Johannes Schindelin
2016-09-06 18:29 ` Jeff King
2016-09-08 7:29 ` Johannes Schindelin
2016-09-08 8:00 ` Jeff King
2016-09-09 10:09 ` Johannes Schindelin
2016-09-09 17:46 ` Junio C Hamano
2016-09-06 13:21 ` Johannes Schindelin
2016-09-06 6:58 ` Jeff King
2016-09-06 14:13 ` Johannes Schindelin
2016-09-08 7:31 ` [PATCH v2 " Johannes Schindelin
2016-09-08 7:31 ` [PATCH v2 2/3] Introduce a function to run regexec() on non-NUL-terminated buffers Johannes Schindelin
2016-09-08 8:04 ` Jeff King
2016-09-09 9:45 ` Johannes Schindelin
2016-09-09 9:59 ` Jeff King
2016-09-08 7:31 ` [PATCH v2 1/3] Demonstrate a problem: our pickaxe code assumes NUL-terminated buffers Johannes Schindelin
2016-09-08 7:31 ` [PATCH v2 3/3] Use the newly-introduced regexec_buf() function Johannes Schindelin
2016-09-08 7:54 ` Johannes Schindelin
2016-09-08 8:10 ` Jeff King
2016-09-08 8:14 ` Jeff King
2016-09-08 8:35 ` Jeff King
2016-09-08 19:06 ` Ramsay Jones
2016-09-08 19:53 ` Jeff King
2016-09-08 21:30 ` Junio C Hamano
2016-09-08 7:33 ` [PATCH v2 0/3] Fix a segfault caused by regexec() being called on mmap()ed data Johannes Schindelin
2016-09-08 8:13 ` Jeff King
2016-09-08 7:57 ` [PATCH v3 " Johannes Schindelin
2016-09-08 7:57 ` [PATCH v3 1/3] Demonstrate a problem: our pickaxe code assumes NUL-terminated buffers Johannes Schindelin
2016-09-08 7:58 ` [PATCH v3 2/3] Introduce a function to run regexec() on non-NUL-terminated buffers Johannes Schindelin
2016-09-08 17:03 ` Junio C Hamano
2016-09-08 7:59 ` [PATCH v3 3/3] Use the newly-introduced regexec_buf() function Johannes Schindelin
2016-09-08 17:09 ` Junio C Hamano
2016-09-09 9:52 ` Johannes Schindelin
2016-09-09 9:57 ` Jeff King
2016-09-09 10:41 ` Johannes Schindelin
2016-09-09 17:49 ` Junio C Hamano
2016-09-21 18:23 ` [PATCH v4 0/3] Fix a segfault caused by regexec() being called on mmap()ed data Johannes Schindelin
2016-09-21 18:23 ` [PATCH v4 1/3] regex: -G<pattern> feeds a non NUL-terminated string to regexec() and fails Johannes Schindelin
2016-09-21 18:24 ` [PATCH v4 2/3] regex: add regexec_buf() that can work on a non NUL-terminated string Johannes Schindelin
2016-09-21 19:17 ` Junio C Hamano
2016-09-22 18:38 ` Johannes Schindelin
2016-09-21 18:24 ` [PATCH v4 3/3] regex: use regexec_buf() Johannes Schindelin
2016-09-21 19:18 ` Junio C Hamano
2016-09-21 20:09 ` Junio C Hamano
2016-09-21 22:03 ` Jeff King
2016-09-25 14:01 ` Johannes Schindelin [this message]
2016-09-21 22:04 ` [PATCH v4 0/3] Fix a segfault caused by regexec() being called on mmap()ed data Jeff King
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