Re: [PATCH] speed up SATA

From: Jeff Garzik
Date: Tue Mar 30 2004 - 12:54:33 EST

Timothy Miller wrote:

Jens Axboe wrote:

- The optimal_sectors calculation is just an average of previous maximum
with current maximum. The scheme has a number of break down points,
for instance writes starving reads will give you a bad read execution
time, further limiting ->optimal_sectors[READ]

I did look through your code a bit, but one thing to be concerned with is that going only on max throughput might be fooled by cache hits on the drive.

If you are taking your samples over time, that shouldn't matter... if the system workload is such that you are hitting the drive cache the majority of the time, you're not being "fooled" by cache hits, the patch would be taking those cache hits into account.

If the system isn't hitting the drive cache the majority of the time, statistical sampling will automatically notice that too...


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