Messages in this thread |  | | | Date | Tue, 21 Apr 2009 23:01:47 -0700 | | From | Andrew Morton <> | | Subject | Re: [PATCH] memcg: remove trylock_page_cgroup |
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On Wed, 22 Apr 2009 13:41:08 +0900 KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > I expect that it will reliably fail if the caller is running as > > SCHED_FIFO and the machine is single-CPU, or if we're trying to yield > > to a SCHED_OTHER task which is pinned to this CPU, etc. The cond_resched() > > won't work. > > > Hm, signal_pending() is supported now (so special user scan use alaram()) > I used yield() before cond_resched() but I was told don't use it. > Should I replace cond_resched() with congestion_wait(HZ/10) or some ?
msleep(1) would be typical. That can also be used to give a predictable number of seconds for the timeout.
If 1 millisecond is too coarse then it's possible to sleep for much shorter intervals if the platform implements hi-res timers. We don't appear to have a handy interface to that (usleep, microsleep, nanosleep, etc?).
And an attempt to sleep for 1us will fall back to 1/HZ if the platform doesn't implement hi-res timers, so that loop will need to be turned into a do {} while(!timer_after(jiffies, start))) thing. Probably it should be converted to that anyway, to be better behaved/predictable, etc.
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