From: Jeff King <peff@peff•net>
To: mhagger@alum•mit.edu
Cc: Junio C Hamano <gitster@pobox•com>, git@vger•kernel.org
Subject: Re: [PATCH] find_containing_dir(): allocate strbuf less extravagantly
Date: Tue, 22 May 2012 13:34:48 -0400 [thread overview]
Message-ID: <20120522173448.GD11600@sigill.intra.peff.net> (raw)
In-Reply-To: <1337692566-3718-1-git-send-email-mhagger@alum.mit.edu>
On Tue, May 22, 2012 at 03:16:06PM +0200, mhagger@alum•mit.edu wrote:
> From: Michael Haggerty <mhagger@alum•mit.edu>
>
> It might seem like allocating a fixed-length buffer of uninitialized
> memory should be pretty cheap even if the buffer is of size PATH_MAX.
> But empirically, it is measurably faster to allocated only the strlen
> of the input string.
>
> Thanks to Peff for pointing out a performance regression in this area
> that might be fixed by this patch.
>
> Signed-off-by: Michael Haggerty <mhagger@alum•mit.edu>
> ---
> I am not able to reproduce performance regressions as bad as those
> observed by Peff. It seems to depend on the amount of memory
> pressure. The smaller regression that I *did* see is fixed by this
> patch, reducing the time for "git fetch . refs/*:refs/*" from 10.1 s
> to 9.3 s. The change is sensible in any case, but we will have to
> wait for Peff's verdict about whether it fixes the whole problem for
> him, too.
I see a similar small improvement. So I think it is worth doing, but it
does not fix the main regression I found.
-Peff
next prev parent reply other threads:[~2012-05-22 17:34 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-22 13:16 [PATCH] find_containing_dir(): allocate strbuf less extravagantly mhagger
2012-05-22 17:34 ` Jeff King [this message]
2012-05-22 18:50 ` [PATCH 1/3] refs: convert parameter of search_ref_dir() to length-limited string René Scharfe
2012-05-22 18:50 ` [PATCH 2/3] refs: convert parameter of create_dir_entry() " René Scharfe
2012-05-22 18:50 ` [PATCH 3/3] refs: use strings directly in find_containing_dir() René Scharfe
2012-05-22 21:27 ` Junio C Hamano
2012-05-22 22:11 ` René Scharfe
2012-05-22 22:18 ` Junio C Hamano
2012-05-23 16:20 ` René Scharfe
2012-05-23 16:56 ` Junio C Hamano
2012-05-23 17:15 ` René Scharfe
2012-05-24 4:34 ` Michael Haggerty
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