Messages in this thread |  | | | Date | Tue, 21 Dec 2010 20:17:33 +0200 | | From | Avi Kivity <> | | Subject | Re: [RFC PATCH 15/15] nohz_task: Procfs interface |
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On 12/21/2010 07:05 PM, Frederic Weisbecker wrote: > > > > For an example of a per-cpu flag that is checked on every exit with > > zero additional overhead on the flag clear case, look at > > TIF_USER_RETURN_NOTIFY. > > Right, but the problem is actually that if we want to automate the nohz > attribute on every tasks, then you need you have this flag set for > all of these threads. > > No problem with that, but if nobody wants the nohz attribute, we don't > need to force that slow path.
When the scheduler detects the task is all alone, it sets the flag; when it blocks, or if another task joins, it drops the flag (at most one task per cpu has the flag set).
Does that work?
-- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.
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