Re: [PATCH v2] xdiff/xprepare: improve O(n*m) performance in xdl_cleanup_records()

From: Jeff King <peff@peff.net>
Date: Aug 17, 2011, 05:21 UTC
Message-ID: <20110817052147.GA11253@sigill.intra.peff.net>
In-Reply-To: <1313546037-4104-1-git-send-email-rctay89@gmail.com>

On Wed, Aug 17, 2011 at 09:53:57AM +0800, Tay Ray Chuan wrote:

Show 19 quoted lines

> > Could we have some benchmarks to let the readers get a feel of how much
> > improvement this patch brings in?
> 
> On my msysgit machine with Marat's problematic repo
> (git://slonopotamus.org/git-diff):
> 
>  rctay@TEST-123 /tmp/slono
>  $ time git show >/dev/null
> 
>  real    0m8.538s
>  user    0m0.000s
>  sys     0m0.031s
> 
>  rctay@TEST-123 /tmp/slono
>  $ time /git/git show >/dev/null
> 
>  real    0m0.672s
>  user    0m0.031s
>  sys     0m0.031s

Wait, what? It was using 0 seconds of user time before, but still taking 8.5 seconds? What was it doing? Did you actually warm up your disk cache before taking these measurements?

-Peff