On Mon, Nov 16, 2015 at 8:11 AM, Victor Leschuk <vlesc...@accesssoftek.com> wrote: > "git grep" can now be configured (or told from the command line) > how many threads to use when searching in the working tree files. > > Changes to default behavior: number of threads now doesn't depend > on online_cpus(), e.g. if specific number is not configured > GREP_NUM_THREADS_DEFAULT (8) threads will be used even on 1-core CPU.
It's good that this behavior change (no longer consulting online_cpus()) is now mentioned[1] in the commit message, however, it's also important for people to understand why this change was made, but such explanation is missing here. It's important to justify the change in the commit message itself since only a few people were involved in the mailing list discussion which led to the change, and even those people may forget the reasoning at some point. Moreover, this change (dropping online_cpus()) is sufficiently significant and distinct from the overall purpose of the present patch (adding --threads and 'grep.threads') that it really deserves its own separate patch (as hinted by [1]), which would turn this into a 2-patch series. [1]: http://article.gmane.org/gmane.comp.version-control.git/281133/ > Signed-off-by: Victor Leschuk <vlesc...@accesssoftek.com> > --- > diff --git a/Documentation/config.txt b/Documentation/config.txt > @@ -1447,6 +1447,13 @@ grep.extendedRegexp:: > +grep.threads:: > + Number of grep worker threads, use it to tune up performance on > + your machines. Leave it unset (or set to 0) for default behavior, > + which for now is using 8 threads for all systems. You could drop "for now", which is redundant with the sentence which follows. > + Default behavior can be changed in future versions > + to better suit hardware and circumstances. "may change" might read better than "can be changed". > gpg.program:: > Use this custom program instead of "gpg" found on $PATH when > making or verifying a PGP signature. The program must support the > diff --git a/Documentation/git-grep.txt b/Documentation/git-grep.txt > @@ -53,6 +54,13 @@ grep.extendedRegexp:: > +grep.threads:: > + Number of grep worker threads, use it to tune up performance on > + your machines. Leave it unset (or set to 0) for default behavior, > + which for now is using 8 threads for all systems. > + Default behavior can be changed in future versions > + to better suit hardware and circumstances. Same comments as above. > @@ -227,6 +235,13 @@ OPTIONS > +--threads <num>:: > + Number of grep worker threads, use it to tune up performance on > + your machines. Leave it unset (or set to 0) for default behavior, > + which for now is using 8 threads for all systems. > + Default behavior can be changed in future versions > + to better suit hardware and circumstances. Ditto. Would it make more sense just to have the detailed description in one place and then reference it from the other places rather than repeating in all places? > diff --git a/builtin/grep.c b/builtin/grep.c > @@ -262,10 +265,19 @@ static int wait_all(void) > +static int grep_threads_config(const char *var, const char *value, void *cb) > +{ > + if (!strcmp(var, "grep.threads")) > + num_threads = git_config_int(var, value); /* Sanity check of > value will be perfomed later */ Nit: This is a pretty wide line. Perhaps the comment could be moved to its own line to stay below 80 columns? > + return 0; > +} > + > static int grep_cmd_config(const char *var, const char *value, void *cb) > { > int st = grep_config(var, value, cb); > - if (git_color_default_config(var, value, cb) < 0) > + if (grep_threads_config(var, value, cb) < 0) > + st = -1; > + else if (git_color_default_config(var, value, cb) < 0) > st = -1; Nit: Custom is to add new cases following existing ones, which would give you a less noisy diff. > return st; > } > @@ -832,14 +846,18 @@ int cmd_grep(int argc, const char **argv, const char > *prefix) > } > > #ifndef NO_PTHREADS > - if (list.nr || cached || online_cpus() == 1) > - use_threads = 0; > + if (list.nr || cached) > + num_threads = 0; /* Can not multi-thread object lookup */ > + else if (num_threads == 0) > + num_threads = GREP_NUM_THREADS_DEFAULT; /* User didn't > specify value, or just wants default behavior */ Nit: Overly wide line. > + else if (num_threads < 0) > + die("Invalid number of threads specified (%d)", num_threads); If you validate the value earlier, rather than delaying it until here, you can give a more useful error message which would state whence the bad value arose (config vs. command-line). This may or may not be a worthwhile improvement. > #else > - use_threads = 0; > + num_threads = 0; > #endif > > #ifndef NO_PTHREADS > - if (use_threads) { > + if (num_threads) { > if (!(opt.name_only || opt.unmatch_name_only || opt.count) > && (opt.pre_context || opt.post_context || > opt.file_break || opt.funcbody)) -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
