Subject: [linux-audio-dev] Re: high level laaga
From: Paul Davis (pbd_AT_Op.Net)
Date: Fri May 11 2001 - 23:30:55 EEST
>However if I interpret right the web page:
>
>"The benchmark times how long it takes to go from one process to another
>when the context switch is done by reading and writing data."
>
>Then I suppose this is not the pure context switch time, but it's
>cumulated with read/write syscall and copy time that seems to be
>significative. Note also that in current kernel code pipe needs a double
>copy (Manfred Spraul is improving that in recent past days).
>
>If (I underline "if") the cost is ~2 microseconds this means 0.1538% of
>CPU use per context switch.
No, lmbench is much better than this. Larry McVoy, who wrote lmbench,
knows what he's doing. Unless these guys misinterpreted the output of
lmbench, then the numbers you see are real context switch times, in
the sense of "the interval from when one process was switched from
until the next one is running".
For the moment I am assuming that the people who did this page
understood enough about to use lmbench to not make such a stupid
mistake.
>However I don't want that this discussion takes too much place: do you
>agree to choose to design one API suitable for both approaches?
If such an API was possible, I would prefer it. But as I've mentioned
before, its not clear to me that such a thing is possible without
compromising aspects of one or other approach.
--p
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