Am 07.12.2011 05:24, schrieb Jeff King:
> On Tue, Dec 06, 2011 at 11:48:26PM +0100, René Scharfe wrote:
>
>> #ifndef NO_PTHREADS
>> - if (use_threads) {
>> + if (nr_threads > 0) {
>> grep_sha1_async(opt, name, sha1);
>> return 0;
>> } else
>
> Should this be "if (nr_threads > 1)"?
>
> As a user, I would do:
>
> git grep --threads=1 ...
>
> if I wanted a single-threaded process. Instead, we actually spawn a
> sub-thread and do all of the locking, which has a measurable cost:
Yes, the difference is measurable, and that's exactly how I like it to
be. :) A user can turn off threading with --threads=0 or (more
intuitively) --no-threads. And we can quantify the overhead.
> $ time git grep --threads=0 SIMPLE HEAD >/dev/null
> real 0m2.994s
> user 0m2.932s
> sys 0m0.060s
>
> $ time git grep --threads=1 SIMPLE HEAD >/dev/null
> real 0m3.407s
> user 0m3.392s
> sys 0m0.140s
>
> Should --threads=1 be equivalent to --threads=0?
We can do that if there's another way to calculate this difference, or
if it is not useful to know. I find your results interesting at least,
though. :)
René
--
To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html