# [PATCH] Speed up commands that use rev-list when max-count is specified. 4 messages from 2010-03-21 to 2010-03-21. Participants: Benjamin C Meyer, Sverre Rabbelier, Mark Lodato, Benjamin Meyer. Thread: https://gitlist.dev/t/23116 ## Benjamin C Meyer, 2010-03-21 03:31 Subject: [PATCH] Speed up commands that use rev-list when max-count is specified. Message-ID: <1269142267-17127-1-git-send-email-bmeyer@rim.com> URL: https://gitlist.dev/e/1269142267-17127-1-git-send-email-bmeyer%40rim.com ``` Many command have code similar to the following: while ((commit = get_revision(rev)) != NULL) { ... } This results in and extra call to get_revision that first finds the next revision and then notices max-count is 0 and returns NULL. Adding a max-count check before any expensive work reduces the runtime of all of the commands the have this pattern. Depending on the use case this can have a big impact on the running time. Signed-off-by: Benjamin C Meyer --- revision.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/revision.c b/revision.c index 490b484..4673d70 100644 --- a/revision.c +++ b/revision.c @@ -2058,6 +2058,9 @@ static struct commit *get_revision_internal(struct rev_info *revs) struct commit *get_revision(struct rev_info *revs) { + if (revs->max_count == 0) + return NULL; + struct commit *c; struct commit_list *reversed; -- 1.7.0.2 ``` ## Sverre Rabbelier, 2010-03-21 11:12 Subject: Re: [PATCH] Speed up commands that use rev-list when max-count is specified. Message-ID: URL: https://gitlist.dev/e/fabb9a1e1003210412n58a3b951x1de4543f11b888c4%40mail.gmail.com In-Reply-To: <1269142267-17127-1-git-send-email-bmeyer@rim.com> ``` Heya, On Sun, Mar 21, 2010 at 04:31, Benjamin C Meyer wrote: > Depending on the use case this can have a big impact on the running time. Sounds promising, do you have any numbers? -- Cheers, Sverre Rabbelier ``` ## Mark Lodato, 2010-03-21 14:09 Subject: Re: [PATCH] Speed up commands that use rev-list when max-count is specified. Message-ID: URL: https://gitlist.dev/e/ca433831003210709k1da46c8docfdac358253625e%40mail.gmail.com In-Reply-To: <1269142267-17127-1-git-send-email-bmeyer@rim.com> ``` On Sat, Mar 20, 2010 at 11:31 PM, Benjamin C Meyer wrote: >  struct commit *get_revision(struct rev_info *revs) >  { > +       if (revs->max_count == 0) > +               return NULL; > + >        struct commit *c; >        struct commit_list *reversed; Declaring variables in the middle of a function is a C99 feature (and a GNU extension in C89 mode). I don't know if this is allowed in git code, but it would be easy enough to make this ANSI C89 compatible by putting your new statement after the variable declarations. ``` ## Benjamin Meyer, 2010-03-21 16:57 Subject: Re: [PATCH] Speed up commands that use rev-list when max-count is specified. Message-ID: <10BD5DAD-16FB-40FB-A77B-955EA0ECD4CB@meyerhome.net> URL: https://gitlist.dev/e/10BD5DAD-16FB-40FB-A77B-955EA0ECD4CB%40meyerhome.net In-Reply-To: ``` In the git repo a more extreme case doing something like git log -1 copy.c the patch will reduce the runtime by 70%. Running it on every top level file in git ('for f in *; log -1 $f; done') goes from 9 minutes to 8:30. -Benjamin Meyer On Mar 21, 2010, at 7:12 AM, Sverre Rabbelier wrote: > Heya, > > On Sun, Mar 21, 2010 at 04:31, Benjamin C Meyer wrote: >> Depending on the use case this can have a big impact on the running time. > > Sounds promising, do you have any numbers? > > -- > Cheers, > > Sverre Rabbelier > -- > To unsubscribe from this list: send the line "unsubscribe git" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html ```