From mboxrd@z Thu Jan 1 00:00:00 1970 From: Colin Cross Subject: [PATCH v3 05/16] freezer: shorten freezer sleep time using exponential backoff Date: Mon, 6 May 2013 16:50:10 -0700 Message-ID: <1367884221-20462-6-git-send-email-ccross@android.com> References: <1367884221-20462-1-git-send-email-ccross@android.com> Cc: Pavel Machek , "Rafael J. Wysocki" , Peter Zijlstra , Ingo Molnar , Andrew Morton , Mandeep Singh Baines , Colin Cross , Oleg Nesterov , linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Linus Torvalds , Tejun Heo , Len Brown To: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Return-path: In-Reply-To: <1367884221-20462-1-git-send-email-ccross-z5hGa2qSFaRBDgjK7y7TUQ@public.gmane.org> Sender: linux-nfs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org All tasks can easily be frozen in under 10 ms, switch to using an initial 1 ms sleep followed by exponential backoff until 8 ms. Also convert the printed time to ms instead of centiseconds. Acked-by: Pavel Machek Acked-by: Tejun Heo Signed-off-by: Colin Cross --- kernel/power/process.c | 26 +++++++++++++++----------- 1 file changed, 15 insertions(+), 11 deletions(-) diff --git a/kernel/power/process.c b/kernel/power/process.c index 98088e0..fc0df84 100644 --- a/kernel/power/process.c +++ b/kernel/power/process.c @@ -30,9 +30,10 @@ static int try_to_freeze_tasks(bool user_only) unsigned int todo; bool wq_busy = false; struct timeval start, end; - u64 elapsed_csecs64; - unsigned int elapsed_csecs; + u64 elapsed_msecs64; + unsigned int elapsed_msecs; bool wakeup = false; + int sleep_usecs = USEC_PER_MSEC; do_gettimeofday(&start); @@ -68,22 +69,25 @@ static int try_to_freeze_tasks(bool user_only) /* * We need to retry, but first give the freezing tasks some - * time to enter the refrigerator. + * time to enter the refrigerator. Start with an initial + * 1 ms sleep followed by exponential backoff until 8 ms. */ - msleep(10); + usleep_range(sleep_usecs / 2, sleep_usecs); + if (sleep_usecs < 8 * USEC_PER_MSEC) + sleep_usecs *= 2; } do_gettimeofday(&end); - elapsed_csecs64 = timeval_to_ns(&end) - timeval_to_ns(&start); - do_div(elapsed_csecs64, NSEC_PER_SEC / 100); - elapsed_csecs = elapsed_csecs64; + elapsed_msecs64 = timeval_to_ns(&end) - timeval_to_ns(&start); + do_div(elapsed_msecs64, NSEC_PER_MSEC); + elapsed_msecs = elapsed_msecs64; if (todo) { printk("\n"); - printk(KERN_ERR "Freezing of tasks %s after %d.%02d seconds " + printk(KERN_ERR "Freezing of tasks %s after %d.%03d seconds " "(%d tasks refusing to freeze, wq_busy=%d):\n", wakeup ? "aborted" : "failed", - elapsed_csecs / 100, elapsed_csecs % 100, + elapsed_msecs / 1000, elapsed_msecs % 1000, todo - wq_busy, wq_busy); if (!wakeup) { @@ -96,8 +100,8 @@ static int try_to_freeze_tasks(bool user_only) read_unlock(&tasklist_lock); } } else { - printk("(elapsed %d.%02d seconds) ", elapsed_csecs / 100, - elapsed_csecs % 100); + printk("(elapsed %d.%03d seconds) ", elapsed_msecs / 1000, + elapsed_msecs % 1000); } return todo ? -EBUSY : 0; -- 1.8.2.1 -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html