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SubjectRe: Calling current() from interrupt context
   Date: 	Tue, 10 Oct 2000 10:54:11 +0100 (BST)
From: Alan Cox <alan@lxorguk.ukuu.org.uk>

Having the stacks aligned also isnt good for the caches. If you are
bored some time instrument the cache lines that wake_up() touches
on a wake. Its very common to see most of them being on the same
line because each kernel thread waiting on the same event (eg poll
in apache) is at the same kernel and user stack depth.

Some of us actually have instrumented it :-) I added a coloring
mechanism to the task/kstack allocator on sparc64. It made no
noticable difference whatsoever to any real life measurement I
attempted.

In my experiments I tried both L1 cache and L2 cache coloring.

Later,
David S. Miller
davem@redhat.com
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