[darcs-users] darcs patch: fpstring.c: switch a memchr for memrchr

Gwern Branwen gwern0 at gmail.com
Fri Apr 25 22:53:26 UTC 2008


On 2008.04.25 13:42:04 -0700, Jason Dagit <dagit at codersbase.com> scribbled 1.9K characters:
>    On Fri, Apr 25, 2008 at 1:26 PM, Don Stewart <dons at galois.com> wrote:
>
>      gwern0:
>      > Fri Apr 25 16:01:53 EDT 2008  gwern0 at gmail.com
>      >   * fpstring.c: switch a memchr for memrchr
>      >   See <http://bugs.darcs.net/issue814>; memrchr speeds up is_funky quite a bit and thus
>      helps whatsnew -s. It doesn't seem to break (any more) tests.
>
>
>      memrchr isn't available on BSDs.
>
>    Furthermore, I didn't see enough tests in Gwern's bug update to convince me that the
>    difference in run-times is attributable to the use of memrchr.
>
>    Jason

I'm not sure how I could've tested it any more: I used a fresh darcs repo, made the simple change, compiled and installed, and tested it on a 9.5GB file 3 or 4 times, each time getting a roughly 40 or 50 second result from 'time'; I then in the same repo tested three or four times using my system's darcs binary (or installing from one of my other darcs darcs repos) and get roughly 1m30s timings.

A single change, which leads to an expected difference multiple times; what did I miss?

--
gwern
chaining DES Freeh INR 1080H M. Oratory 747 Fax UNICE
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