On Wed, Mar 23, 2011 at 1:33 PM, David Levin <le...@google.com> wrote: > > > On Wed, Mar 23, 2011 at 12:17 PM, Adam Barth <aba...@webkit.org> wrote: >> >> $ time git svn rebase >> [... update my working copy from changes during lunch (four revisions) >> ...] >> real 1m10.316s >> user 0m8.194s >> sys 0m16.400s >> >> $ time ./Tools/Scripts/generate-project-files >> real 0m4.339s >> user 0m3.888s >> sys 0m0.269s >> >> which is about 6.1% overhead on an almost trivial update. We can also >> reduce this overhead to zero in many cases by detecting that we don't >> need to re-generate the project files if the inputs to the generation >> process haven't changed. >> > It looks like you are using a slow mechanism for syncing. :) > TLDR version: 8% overhead for updating 191 revisions. 49% overhead for > trivial sync (3 revisions) -- in addition to the added complexity (when I > sync or switch branches in git). > Here's my results for updating 191 revisions (81605 through 81796). > > $ time git fetch && time git svn rebase > > fetch, svn rebase times > real 0m21.071s, 0m36.195s > user 0m2.271s, 0m3.205s > sys 0m0.497s, 0m9.428s > total 57 seconds for a nontrivial update. > $ time ./Tools/Scripts/generate-project-files > real 0m4.642s > user 0m4.243s > sys 0m0.322s > > An 8% overhead on a non-trivial sync. > > For a trivial update of 3 revisions: > real 0m3.490s, 0m6.017s > user 0m0.932s, 0m2.266s > sys 0m0.184s, 0m2.824s > For a total of 9.5 seconds. > > The generate project files step remained the same, so this adds a 49% > overhead for a trivial sync. > It also adds time (and complications) whenever I switch branches in git. > dave > PS For chromium, my experience is > $ time gclient runhooks --force > real 0m42.459s > user 0m29.236s > sys 0m2.543s > I don't know enough about chromium build system and gyp to know why it is an > order of magnitude slower, but this overhead is noticeable and annoying > there. I love the idea of a one project file system, but I have concerns > about project file generation on sync becoming the norm in WebKit. fwiw, I > checked how many gyp files were in chromium and it appeared within 20%. >
FWIW, with Chromium, the regular 'gclient sync' regenerates the project files even if it didn't update anything, which is a step that could probably be eliminated. Also, as far as I know, there's been little effort to profile and optimize gyp, so I bet we could probably speed things up a fair amount. -- Dirk _______________________________________________ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
