lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Wed, 14 Nov 2007 14:43:33 -0500 From: "Alan D. Brunelle" <Alan.Brunelle@...com> To: Arjan van de Ven <arjan@...radead.org> Cc: Ingo Molnar <mingo@...e.hu>, Andrew Morton <akpm@...ux-foundation.org>, Rik van Riel <riel@...hat.com>, jens.axboe@...cle.com, linux-kernel@...r.kernel.org Subject: Re: [patch] Give kjournald a IOPRIO_CLASS_RT io priority Arjan van de Ven wrote: > On Wed, 14 Nov 2007 18:18:05 +0100 > Ingo Molnar <mingo@...e.hu> wrote: > > >> * Andrew Morton <akpm@...ux-foundation.org> wrote: >> >> >>> ooh, more performance testing. Thanks >>> >>> >>>> * The overwriter task (on an 8GiB file), average over 10 runs: >>>> o 2.6.24 - 300.88226 seconds >>>> o 2.6.24 + Arjan's patch - 403.85505 seconds >>>> >>>> * The read-a-different-kernel-tree task, average over 10 runs: >>>> o 2.6.24 - 46.8145945549 seconds >>>> o 2.6.24 + Arjan's patch - 39.6430601119 seconds >>>> >>>> * The large-linear-read task (on an 8GiB file), average over >>>> 10 runs: o 2.6.24 - 290.32522 seconds >>>> o 2.6.24 + Arjan's patch - 386.34860 seconds >>>> >>> These are *large* differences, making this a very signifcant >>> patch. Much care is needed now. >>> >> and the numbers suggest it's mostly a severe performance regression. >> That's not what i have expected - ho hum. Apologies for my earlier >> "please merge it already!" whining. >> > > that's.. not automatic; it depends on what the right thing is :-( > What for sure changes is that who gets to do IO changes. Some of the > tests we ran internally (we didn't publish yet because we saw REALLY > large variations for most of them even without any patch) show for > example that "dbench" got slower. But.. dbench gets slower when things > get more fair, and faster when things get unfair. What conclusion you > draw out of that is a whole different matter and depends on exactly > what the test is doing, and what is the right thing for the OS to do in > terms of who gets to do the IO. > > THis makes the patch more tricky than the one line change suggests, and > this is also why I haven't published a ton of data yet; it's hard to > get useful tests for this (and the variation of the 2.6.23+ kernels > makes it even harder to do anything meaningful ;-( ) > > > I'd also like to point out here that the run-to-run deviation was indeed quite large for both the unpatched- and patched-kernels, I'll report on that information with the next set of results... Alan - 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/
Powered by blists - more mailing lists