On Tue, 07 Dec 2010 15:22:55 -0600 Eric Sandeen <sandeen@xxxxxxxxxx> wrote: > On 12/7/10 3:07 PM, Andrew Morton wrote: > > On Tue, 07 Dec 2010 11:51:05 -0600 > > Eric Sandeen <sandeen@xxxxxxxxxx> wrote: > > > >> The addition of 64k block capability in the rec_len_from_disk > >> and rec_len_to_disk functions added a bit of math overhead which > >> slows down file create workloads needlessly when the architecture > >> cannot even support 64k blocks, thanks to page size limits. > >> > >> The directory entry checking can also be optimized a bit > >> by sprinkling in some unlikely() conditions to move the > >> error handling out of line. > >> > >> bonnie++ sequential file creates on a 512MB ramdisk speeds up > >> from about 2200/s to about 2500/s, about a 14% improvement. > >> > > > > hrm, that's an improbably-large sounding improvement from eliminating > > just a few test-n-branches from a pretty heavyweight operation. > > And yet ... > > Yeah, I dunno. Part of it is that ext2_add_link does a linear > search, so when you do rec_len_from_disk 50,000 times on a dir, > that little bit adds up quite badly I suppose. oh yeah, that would do it. > Retesting at a bunch of different number-of-files in bonnie > (with a small sample size so probably a little noise) > > |files per sec| > files stock patched delta > 10,000 12300 14700 +19% > 20,000 6300 7600 +20% > 30,000 4200 5000 +20% > 40,000 3150 3700 +17% > 50,000 2500 3000 +20% > > (again all on a 512MB ramdisk) > > *shrug* I'll believe my lyin' eyes, I guess. :) > I bet other tweaks in there would yield similar goodliness. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
