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Message-id: <4127129.ClfhyhZXo5@amdc1032> Date: Thu, 11 Sep 2014 15:36:31 +0200 From: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com> To: Alexander Gordeev <agordeev@...hat.com> Cc: Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org, linux-ide@...r.kernel.org Subject: Re: [PATCH RESEND 0/1] AHCI: Optimize interrupt processing Hi, On Thursday, September 11, 2014 02:42:49 PM Alexander Gordeev wrote: > The numbers are taken by running 'dd if=/dev/sd{a,b} of=/dev/null' > in parallel. All time values are in us. > > Before this update host lock average holdtime was 2.45 and > average waittime was 1.24. After the update average holdtime > dropped to 0.29 (about eight times) while average waittime > decreased to 0.58 (about two times). > > Also, port events are handled with local interrupts enabled > and compete on individual per-port locks with average holdtime > 1.25 and average waittime 1.48. So combined average holdtime > spent while holding host and port locks decreased from 2.45 to > 0.29 + 1.25 = 1.54 (about 1.6 times). > > The downside of this change is introduction of a kernel thread. > > The upside is shorter access time to port locks and moving port > interrupts handling out of the hardware interrupt context. IMHO it would be great to put the above results into the patch description (it now looks a bit skimpy). Best regards, -- Bartlomiej Zolnierkiewicz Samsung R&D Institute Poland Samsung Electronics -- 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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