Device-level IO blocking [LWN.net]

Device-level IO blocking

Posted Oct 2, 2007 9:11 UTC (Tue) by Jel (guest, #22988)
Parent article: Smarter write throttling

Device-level IO blocking doesn't seem granular enough. Isn't there some
way to manage disk writes with awareness of platters/heads and access
times, so that you essentially gain the performance benefits of RAID?

That would be a much nicer layer to queue IO at.

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Device-level IO blocking

Posted Oct 2, 2007 17:30 UTC (Tue) by njs (guest, #40338) [Link]

I doubt that would make much difference -- the goal is that the rate at which writes are queued should match the rate at which writes are completed. Since there is a buffer, these rates don't have to match in fine detail; they only have to match on average.

Even over long time periods, different devices will be more or less fast; but the differences within a device tend (I believe) to wash out over any time period longer than a few hundred milliseconds.