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SubjectRe: wait queue question
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V Ganesh <ganesh@vxindia.veritas.com> writes:

> is there any need we maintain wait queues as circular lists ?
> the only reason I can think of is that we might have to remove an
> element without knowing which list it belongs to. but __remove_wait_queue
> is passed the address of the list head and just ignores it, going the full
> circle every time. seems to me that it might be slightly faster, on the
> average, to use good old linear null-terminated lists. plus we would
> avoid the hairiness of WAIT_QUEUE_HEAD.

About two years ago, in the days of 2.0.30 and 2.1.43, I carefully
tuned __{add,remove}_wait_queue in kernel-typical contexts for
gcc-2.7.2 on i586s & K5s for speed and size. I had a version of
__remove_wait_queue using the wait_queue argument too. It didn't
crash linux in my configuration, but I decided not to use it, as it
could have exposed broken kernel-code and I didn't want to risk to
break anything.

Using the list argument to remove_wait_queue in my opinion is not
something to do in the 2.2.x series.

Christian.

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