Messages in this thread | | | Date | Thu, 1 Oct 2009 20:36:55 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH 01/19] freezer: don't get over-anxious while waiting |
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> Freezing isn't exactly the most latency sensitive operation and > there's no reason to burn cpu cycles and power waiting for it to > complete. msleep(10) instead of yield(). This should improve > reliability of emergency hibernation.
i don't see how it improves reliability, but its probably ok.
Well... for hibernation anyway. I can imagine cgroup users where freeze is so fast that this matters. rjw cc-ed. pavel
> Signed-off-by: Tejun Heo <tj@kernel.org> > --- > kernel/power/process.c | 13 +++++++++---- > 1 files changed, 9 insertions(+), 4 deletions(-) > > diff --git a/kernel/power/process.c b/kernel/power/process.c > index cc2e553..9d26a0a 100644 > --- a/kernel/power/process.c > +++ b/kernel/power/process.c > @@ -41,7 +41,7 @@ static int try_to_freeze_tasks(bool sig_only) > do_gettimeofday(&start); > > end_time = jiffies + TIMEOUT; > - do { > + while (true) { > todo = 0; > read_lock(&tasklist_lock); > do_each_thread(g, p) { > @@ -62,10 +62,15 @@ static int try_to_freeze_tasks(bool sig_only) > todo++; > } while_each_thread(g, p); > read_unlock(&tasklist_lock); > - yield(); /* Yield is okay here */ > - if (time_after(jiffies, end_time)) > + if (!todo || time_after(jiffies, end_time)) > break; > - } while (todo); > + > + /* > + * We need to retry. There's no reason to be > + * over-anxious about it and waste power. > + */ > + msleep(10); > + } > > do_gettimeofday(&end); > elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start);
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