Re: Make pipe data structure be a circular list of pages, ratherthan

From: Linus Torvalds
Date: Sat Jan 08 2005 - 23:08:59 EST




On Sat, 8 Jan 2005, Linus Torvalds wrote:
>
> Short and sweet: the latency changes are in the noise for SMP, but can be
> seen on UP. I'll look at it a bit more: since I had to add the coalescing
> code anyway, I might also decide to re-use a buffer page rather than free
> it immediately, since that may help latency for small writes.

Side note: the SMP numbers seem to fluctuate wildly making any
benchmarking a bit suspect. They probably depend very much on just how
things get scheduled, and on inter-CPU cache behaviour.

In contrast, the UP numbers are a lot more reliable, so I'll try to make
sure that everything looks good on UP - which definitely means that I'll
work to make sure that latency looks good too.

Linus
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