Andi Kleen wrote:
On Mon, Dec 12, 2005 at 03:14:53PM +1100, Nick Piggin wrote:
Cool. That is a patch that should go on top of mine, because most of
my patch is aimed at moving modifications under interrupts-off sections,
That's obsolete then.
No it isn't.
With local_t you don't need to turn off interrupts
anymore.
Then you can't use __local_xxx, and so many architectures will use
atomic instructions (the ones who don't are the ones with tripled
cacheline footprint of this structure).
Sure i386 and x86-64 are happy, but this would probably slow down
most other architectures.
However I'm still worried about the use of locals tripling the cacheline
size of a hot-path structure on some 64-bit architectures. Probably we
should get them to try to move to the atomic64 scheme before using
local_t here.
I think the right fix for those is to just change the fallback local_t
to disable interrupts again - that should be a better tradeoff and
when they have a better alternative they can implement it in the arch.
Probably right.
(in fact i did a patch for that too, but considered throwing it away
again because I don't have a good way to test it)
Yep, it will be difficult to test.
--
SUSE Labs, Novell Inc.
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