Messages in this thread | | | Date | Thu, 28 Aug 2008 12:40:03 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH] make poll_idle behave more like the other idle methods |
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On Thu, 28 Aug 2008, Ingo Molnar wrote: > * Joe Korty <joe.korty@ccur.com> wrote: > > > Make poll_idle() behave more like the other idle methods. > > > > Currently, poll_idle() returns immediately. The other > > idle methods all wait indefinately for some condition > > to come true before returning. poll_idle should emulate > > these other methods and also wait for a return condition, > > in this case, for need_resched() to become 'true'. > > > > Without this delay the idle loop spends all of its time > > in the outer loop that calls poll_idle. This outer loop, > > these days, does real work, some of it under rcu locks. > > That work should only be done when idle is entered and > > when idle exits, not continuously while idle is spinning. > > i'm wondering, what's the motivation, have you actually seen > anything bad/undesired happen due to that?
Hmm, two observations:
1) I think Joe is right that idle_poll should behave like any other idle function.
2) I wonder whether the work you observe is something we should investigate. The only code which does work in the idle loop is rcu_check_callbacks(). What kind of work load scenario do you have which makes the rcu_check_callbacks() called ?
Thanks,
tglx
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