On Sat, Jul 27, 2013 at 4:15 PM, Richard Hipp <d...@sqlite.org> wrote:
> > > On Sat, Jul 27, 2013 at 3:41 PM, Eric Rubin-Smith <eas....@gmail.com>wrote: > >> On Sat, Jul 27, 2013 at 3:23 PM, Richard Hipp <d...@sqlite.org> wrote: >> >>> What's the total size of all those files (how big is the checkout)? >>> >> >> [monk:repo.fossil] $ du -sch . >> 392M . >> 392M total >> > > > That would be the culprit. As one of several "self-checks" (see > http://www.fossil-scm.org/fossil/doc/trunk/www/selfcheck.wiki), Fossil > always computes an MD5 checksum over the entire check-out and compares that > to the content being checked in, to make sure they are identical. With a > 392MB checkout on an older machine, that might easily take a minute. > I tested this basic claim and do not believe it holds: [monk:~] $ head -c $(echo 392*1024*1024|bc) /dev/zero > foo [monk:~] $ du -sch foo 392M foo 392M total [monk:~] $ time md5sum foo c6d8f8fc5c75fd6ecceb4edf42f3ac4d foo real 0m1.324s user 0m0.998s sys 0m0.247s So just over a second to calculate that hash on the same box. I retried this after dropping kernel caches to test whether it's the disk, and it still only took 3.6 seconds to calculate the hash. Of course, that's just the time it takes to calculate the hash. Obviously it does not include the time spent concatenating the world together to send to your MD5 function. Perhaps there's a super-linear algorithm in that concatenation stuff? Turning off repo-cksum* **did* address the issue, at least by an order of magnitude: [monk:code] $ fossil setting repo-cksum off [monk:code] $ time fossil commit -m "test commit" New_Version: 4d3b92dca8a617d6004bbe4e9c158fc11882720d real 0m7.365s user 0m0.627s sys 0m0.398s Does this leave any serious gaps in fault-tolerance? The new performance is acceptable, though I'm still happy to keep digging around if you're still curious (either about what was taking so long, or about what is still taking 7 seconds, or both). Thanks Richard. Eric
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