On Thu, 2008-01-10 at 00:43 +0200, Pekka J Enberg wrote: > Hi Matt, > > On Wed, 9 Jan 2008, Matt Mackall wrote: > > I kicked this around for a while, slept on it, and then came up with > > this little hack first thing this morning: > > > > ------------ > > slob: split free list by size > > > > [snip] > > > And the results are fairly miraculous, so please double-check them on > > your setup. The resulting statistics change to this: > > [snip] > > > So the average jumped by 714k from before the patch, became much more > > stable, and beat SLUB by 287k. There are also 7 perfectly filled pages > > now, up from 1 before. And we can't get a whole lot better than this: > > we're using 259 pages for 244 pages of actual data, so our total > > overhead is only 6%! For comparison, SLUB's using about 70 pages more > > for the same data, so its total overhead appears to be about 35%. > > Unfortunately I only see a slight improvement to SLOB (but it still gets > beaten by SLUB): > > [ the minimum, maximum, and average are captured from 10 individual runs ] > > Free (kB) Used (kB) > Total (kB) min max average min max average > SLUB (no debug) 26536 23868 23892 23877.6 2644 2668 2658.4 > SLOB (patched) 26548 23456 23708 23603.2 2840 3092 2944.8 > SLOB (vanilla) 26548 23472 23640 23579.6 2908 3076 2968.4 > SLAB (no debug) 26544 23316 23364 23343.2 3180 3228 3200.8 > SLUB (with debug) 26484 23120 23136 23127.2 3348 3364 3356.8
With your kernel config and my lguest+busybox setup, I get: SLUB: MemFree: 24208 kB MemFree: 24212 kB MemFree: 24212 kB MemFree: 24212 kB MemFree: 24216 kB MemFree: 24216 kB MemFree: 24220 kB MemFree: 24220 kB MemFree: 24224 kB MemFree: 24232 kB avg: 24217.2 SLOB with two lists: MemFree: 24204 kB MemFree: 24260 kB MemFree: 24260 kB MemFree: 24276 kB MemFree: 24288 kB MemFree: 24292 kB MemFree: 24312 kB MemFree: 24320 kB MemFree: 24336 kB MemFree: 24396 kB avg: 24294.4 Not sure why this result is so different from yours. Hacked this up to three lists to experiment and we now have: MemFree: 24348 kB MemFree: 24372 kB MemFree: 24372 kB MemFree: 24372 kB MemFree: 24372 kB MemFree: 24380 kB MemFree: 24384 kB MemFree: 24404 kB MemFree: 24404 kB MemFree: 24408 kB avg: 24344.4 Even the last version is still using about 250 pages of storage for 209 pages of data, so it's got about 20% overhead still. -- Mathematics is the supreme nostalgia of our time. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
