On Wednesday, May 01, 2013 06:34:58 PM Colin Cross wrote: > On slow cpus the large number of task wakeups and context switches > triggered by freezing and thawing tasks can take a significant amount > of cpu time. This patch series reduces the amount of work done during > freezing tasks by avoiding waking up tasks that are already in a freezable > state. > > The first patch reduces the wasted time in try_to_freeze_tasks() by > starting with a 1 ms sleep during the first loop and backing off > up to an 8 ms sleep if all tasks are not frozen. > > The second patch modifies the freeze_task() function to skip tasks > that have set the PF_FREEZER_SKIP flag by calling freezer_do_not_count(). > These tasks will not enter the refrigerator during the suspend/resume > cycle unless they woken up by something else, in which case they will > enter the refrigerator in freezer_count() before they access any > resources that would not be available in suspend or deadlock with > another freezing/frozen task. > > The rest of the series adds a few more freezable helpers and converts the > top call sites that userspace tasks are usually blocked at to freezable > helpers. The list of call sites was collected on a Nexus 10 (ARM Exynos > 5250 SoC), but all the top call sites other than binder show up at the > top of the list on Ubuntu x86-64 as well. > > This series cuts the time for freezing tasks from 50 ms to 5 ms when > the cpu speed is locked at its lowest setting (200MHz), and reduces > the number of context switches and restarted syscalls from 1000 to > 25. > > v2 moves the skip check to freeze_task(), and expands the commit > messages.
The entire series makes sense to me, so are there any objections? Tejun, Oleg?? Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
