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SubjectRe: cciss updates for 2.6.6xxx [1/2]
mikem@beardog.cca.cpqcorp.net wrote:
> This patch adds per logical device queues to the HP cciss driver. It currently only implements a single lock but when time permits I will provide that funtionality. Thanks to Jeff Garzik for providing some sample code.
> This patch built against 2.6.5. Please consider this for inclusion.


I appreciate the credit but I don't see that it addressed my original
objection -- the starvation issue.

Do you cap the number of per-array requests a "1024 / n_arrays", or
something like that? You mentioned that the hardware has a maximum of
1024 outstanding commands, for all devices. The two typical solutions
are a round-robin queue (see carmel.c) or limiting each array such that
if all arrays are full of commands, the total outstanding never exceeds
1024.

This patch may be OK for -mm, I would rather not see it go upstream --
it seems to me you are choosing to decrease stability to obtain a
performance increase. I think you can increase performance without
decreasing stability.

Jeff



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