Re: [RFC] buddy optimizations.

From: Linus Torvalds (
Date: Wed May 24 2000 - 16:58:02 EST

In article <>,
Manfred Spraul <> wrote:
>I'm still testing our memory allocators, and I added a per-cpu linked
>list for order==0 to page_alloc:

Manfred, if you _really_ want to speed up the buddy allocator on an SMP
machine, there's a much simpler way: make sure that the
"test_and_change_bit()" thing is not run with the "lock" prefix.

That should speed things up quite noticeably, it doesn't need a locked
access because the per-zone spinlock already guarantees serialization.

Should give you about 10 cycles per bit-change (how many there are
depends on how deep in the buddy system it coalesces..)


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