Re: [PATCH] sha1_name: cache readdir(3) results in find_short_object_filename()

> Am 23.06.2017 um 01:10 schrieb Jeff King:
> > On Thu, Jun 22, 2017 at 08:19:48PM +0200, René Scharfe wrote:
> > 
> >> Read each loose object subdirectory at most once when looking for unique
> >> abbreviated hashes.  This speeds up commands like "git log --pretty=%h"
> >> considerably, which previously caused one readdir(3) call for each
> >> candidate, even for subdirectories that were visited before.
> > 
> > Is it worth adding a perf test that's heavy on abbreviations?
> 
> Sure.  Here's a simple one.  It currently reports for me:
> 
> Test                        origin/master     origin/next              origin/pu
> ---------------------------------------------------------------------------------------------
> 4205.1: log with %H         0.44(0.41+0.02)   0.43(0.42+0.01) -2.3%    0.43(0.43+0.00) -2.3%
> 4205.2: log with %h         1.03(0.60+0.42)   1.04(0.64+0.39) +1.0%    0.57(0.55+0.01) -44.7%
> 4205.3: log with %T         0.43(0.42+0.00)   0.43(0.42+0.01) +0.0%    0.43(0.40+0.02) +0.0%
> 4205.4: log with %t         1.05(0.64+0.38)   1.05(0.61+0.42) +0.0%    0.59(0.58+0.00) -43.8%
> 4205.5: log with %P         0.45(0.42+0.02)   0.43(0.42+0.00) -4.4%    0.43(0.42+0.01) -4.4%
> 4205.6: log with %p         1.21(0.63+0.57)   1.17(0.68+0.47) -3.3%    0.59(0.58+0.00) -51.2%
> 4205.7: log with %h-%h-%h   1.05(0.64+0.39)   2.00(0.83+1.15) +90.5%   0.69(0.66+0.02) -34.3%
> 
> origin/next has fe9e2aefd4 (pretty: recalculate duplicate short hashes),
> while origin/pu has cc817ca3ef (sha1_name: cache readdir(3) results in
> find_short_object_filename()).