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Date: Tue, 15 May 2007 22:04:10 +0200 From: "Kacper Wysocki" <kacperw@...ine.no> To: linux-kernel@...r.kernel.org, ck@....kolivas.org Subject: Re: [ck] Swap prefetch tester On 5/14/07, Con Kolivas <kernel@...ivas.org> wrote: > On Monday 14 May 2007 12:10, Con Kolivas wrote: > > I've had a few requests for a standalone patch implementing swap prefetch > > for mainline. > > > > Here is a patch that is a current rollup that should apply and work for > > vanilla 2.6.21 (ie not a -ck kernel): > > > > http://ck.kolivas.org/patches/swap-prefetch/2.6.21-swap_prefetch-38.patch > Oh and here is the swap prefetch tester: > http://ck.kolivas.org/patches/swap-prefetch/sp_tester.c Some results on my 5-year-old dual AMD2400+ with 1GB mem: ***This one done while in X, 2.6.21.1-reiser4-ck1, sp ON Ram 1034228000 Swap 1959920000 Total ram to be malloced: 1551342000 bytes Starting first malloc of 775671000 bytes Starting 1st read of first malloc Touching this much ram takes 6333 milliseconds Starting second malloc of 775671000 bytes Completed second malloc and free Sleeping for 600 seconds Important part - starting reread of first malloc Completed read of first malloc Timed portion 103277 milliseconds ***This one done while in X, 2.6.21.1-reiser4-ck-sp38, sp ON Ram 1034228000 Swap 1959920000 Total ram to be malloced: 1551342000 bytes Starting first malloc of 775671000 bytes Starting 1st read of first malloc Touching this much ram takes 11674 milliseconds Starting second malloc of 775671000 bytes Completed second malloc and free Sleeping for 600 seconds Important part - starting reread of first malloc Completed read of first malloc Timed portion 24660 milliseconds ...a nice order of magnitude better! Very happy you fixed this Con. But the time to touch was so different (11674 vs 6333ms) that I decided to get out of X, and also check the difference when SP is off. # ./sp_tester; echo 0 > /proc/sys/vm/swap_prefetch ; ./sp_tester ***This one done in the console at runlevel 2, 2.6.21.1-reiser4-ck-sp38, sp ON Ram 1034228000 Swap 1959920000 Total ram to be malloced: 1551342000 bytes Starting first malloc of 775671000 bytes Starting 1st read of first malloc Touching this much ram takes 5709 milliseconds Starting second malloc of 775671000 bytes Completed second malloc and free Sleeping for 600 seconds Important part - starting reread of first malloc Completed read of first malloc Timed portion 22243 milliseconds ***This one done in the console at runlevel 2, 2.6.21.1-reiser4-ck-sp38, sp OFF Ram 1034228000 Swap 1959920000 Total ram to be malloced: 1551342000 bytes Starting first malloc of 775671000 bytes Starting 1st read of first malloc Touching this much ram takes 5816 milliseconds Starting second malloc of 775671000 bytes Completed second malloc and free Sleeping for 600 seconds Important part - starting reread of first malloc Completed read of first malloc Timed portion 28641 milliseconds Have I understood correctly that there are more prefetch improvements in ck2 than just the sp38 patch? I'll post more results if I ever manage to tear myself from the computer for 10 minutes when I'm home - it looks like I have a yiff daemon running at 7% cpu all the time which might have affected the results. Speaking of "feel", the net effect of swap prefetch for me seems to be that I don't notice it - that is, I don't notice my programs behaving sluggishly when I come back to the computer. Excellent! -K - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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