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Message-ID: <20141005161646.GB22223@mtj.dyndns.org> Date: Sun, 5 Oct 2014 12:16:46 -0400 From: Tejun Heo <tj@...nel.org> To: Alexander Gordeev <agordeev@...hat.com> Cc: linux-kernel@...r.kernel.org, linux-ide@...r.kernel.org Subject: Re: [PATCH RESEND v3 5/6] AHCI: Optimize single IRQ interrupt processing A bit of addition. On Sat, Oct 04, 2014 at 10:23:11PM -0400, Tejun Heo wrote: > Hmmm.... so, AFAICS, there's no real pros or cons of going either way, > right? The only thing which could be different is possibly slightly > lower latency in servicing other IRQs or RT tasks on the same CPU but > given that the ahci IRQ handler already doesn't do anything which > takes time, I'm doubtful whether that'd be anything measureable. > > I just don't get why ahci bothers with threaded irq, MMSI or not. I think the thing which bothers me is that due to softirq we end up bouncing the context twice. IRQ schedules threaded IRQ handler after doing minimal amount of work. The threaded IRQ handler gets scheduled and again it doesn't do much but basically just schedules block softirq to actually run completions which is the heavier part. Apparently this doesn't seem to hurt measureably but it's just weird. Why are we bouncing the context twice? Thanks. -- tejun -- 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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