Re: pipe performance regression on ia64

From: David Mosberger
Date: Tue Jan 18 2005 - 13:32:04 EST


>>>>> On Tue, 18 Jan 2005 10:11:26 -0800 (PST), Linus Torvalds <torvalds@xxxxxxxx> said:

Linus> I don't know how to make the benchmark look repeatable and
Linus> good, though. The CPU affinity thing may be the right thing.

Perhaps it should be split up into three cases:

- producer/consumer pinned to the same CPU
- producer/consumer pinned to different CPUs
- producer/consumer lefter under control of the scheduler

The first two would let us observe any changes in the actual pipe
code, whereas the 3rd case would tell us which case the scheduler is
leaning towards (or if it starts doing something real crazy, like
reschedule the tasks on different CPUs each time, we'd see a bandwith
lower than case 2 and that should ring alarm bells).

--david
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