From: Jeff King Date: Fri, 02 Nov 2012 15:26:16 GMT Subject: Re: [PATCH] update-index/diff-index: use core.preloadindex to improve performance Message-ID: <20121102152616.GD11170@sigill.intra.peff.net> In-Reply-To: On Tue, Oct 30, 2012 at 10:50:42AM +0100, karsten.blees@dcon.de wrote: > 'update-index --refresh' and 'diff-index' (without --cached) don't honor > the core.preloadindex setting yet. Porcelain commands using these (such as > git [svn] rebase) suffer from this, especially on Windows. > > Use read_cache_preload to improve performance. > > Additionally, in builtin/diff.c, don't preload index status if we don't > access the working copy (--cached). > > Results with msysgit on WebKit repo (2GB in 200k files): > > | update-index | diff-index | rebase > ----------------+--------------+------------+--------- > msysgit-v1.8.0 | 9.157s | 10.536s | 42.791s > + preloadindex | 9.157s | 10.536s | 28.725s > + this patch | 2.329s | 2.752s | 15.152s > + fscache [1] | 0.731s | 1.171s | 8.877s Cool numbers. On my quad-core SSD Linux box, I saw a few speedups, too. Here are the numbers for "update-index --refresh" on the WebKit repo (all are wall clock time, best-of-five): | before | after -----------+--------+-------- cold cache | 4.513s | 2.059s warm cache | 0.252s | 0.164s Not as dramatic, but still nice. I wonder how a spinning disk would fare on the cold-cache case, though. I also tried it with all but one CPU disabled, and the warm cache case was a little bit slower. Still, I don't think we need to worry about performance regressions, because people who don't have a setup suitable for it will not turn on core.preloadindex in the first place. And if they have it on, the more places we use it, probably the better. -Peff -- *** Please reply-to-all at all times *** *** (do not pretend to know who is subscribed and who is not) *** *** Please avoid top-posting. *** The msysGit Wiki is here: https://github.com/msysgit/msysgit/wiki - Github accounts are free. You received this message because you are subscribed to the Google Groups "msysGit" group. To post to this group, send email to msysgit@googlegroups.com To unsubscribe from this group, send email to msysgit+unsubscribe@googlegroups.com For more options, and view previous threads, visit this group at http://groups.google.com/group/msysgit?hl=en_US?hl=en