Re: [PATCH 1/4, v2] x86: enlightenment for ticket spin locks - base implementation

From: Jan Beulich
Date: Wed Jun 30 2010 - 07:54:34 EST


>>> On 30.06.10 at 13:48, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> On Wed, 2010-06-30 at 12:43 +0100, Jan Beulich wrote:
>
>> It does tickle just the new owner - that's what the list is for.
>
> But if you have a FIFO list you don't need the ticket stuff and can
> implement a FIFO lock instead.

The list is LIFO (not FIFO, as only the most recently added entry is
a candidate for needing wakeup as long as there's no interrupt
re-enabling in irqsave lock paths), and is only used for tickling (not
for deciding who's going to be the next owner).

Jan

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