On Tuesday, March 11, 2014 03:35:06 PM Rik van Riel wrote: > On 03/07/2014 07:12 AM, Rafael J. Wysocki wrote: > > On Wednesday, February 26, 2014 01:46:25 AM Rafael J. Wysocki wrote: > >> On Monday, February 24, 2014 08:29:30 AM Tuukka Tikkanen wrote: > >>> This set of patches makes some minor changes to menu governor and the poll > >>> idle state. > >>> > >>> Patch 1 is simply a rename of a variable to make the name better represent > >>> the contained information. > >>> > >>> Patch 2 fixes calculating actual residency in cases where the entered > >>> state > >>> is different from the state decided by the menu governor. > >>> > >>> Patch 3 makes sure the menu governor timer coefficients are not updated > >>> with values that might cause a coefficient to reach a value greater than > >>> unity. > >>> > >>> Patch 4 fixes calculation actual residency in cases where the entered > >>> state > >>> does not support measuring residency. In such cases the residency time > >>> is taken from time remaining until next timer expiry. The timer is > >>> expected > >>> to go off at the start of exit latency, not after it. Therefore the exit > >>> latency must not be substracted from the assumed value. > >>> > >>> Patch 5 moves the performance multiplier based comparison out of the state > >>> selection loop by changing it into a latency requirement. This allows > >>> using a generic state selection function accepting only (duration, > >>> latency) > >>> tuple as input. The change is possible by noting that performance > >>> multiplier > >>> is used only to check for a minimum predicted idle duration to exit > >>> latency > >>> ratio. As predicted idle duration is a constant for the loop, the maximum > >>> allowed latency can be calculated outside of the loop. > >>> > >>> Patch 6 prevents using negative values from tick_nohz_get_sleep_length() > >>> in the menu governor. If unchecked, the negative values are used as huge > >>> unsigned values. Negative values occur fairly often (e.g. on x86_64 I've > >>> seen this happen several times per minute) on a busy system, allowing > >>> the deepest state to win the selection while the shallowest should be > >>> picked. > >>> > >>> Patch 7 adds CPUIDLE_FLAG_TIME_VALID to poll_idle. I do not know of any > >>> platfrom where cpu_relax() would break ktime_get() and in fact poll_idle > >>> uses ktime_get itself. > >>> (Note: poll_idle updates dev->last_residency for some reason. Does it ever > >>> get called without going through cpuidle_enter_state, which will overwrite > >>> the value? Even if some state redirects to this state, the call will > >>> eventually return to the framework. The redundant time measurement could > >>> be removed, unless there is some obscure way of getting called on some > >>> platform that I am unable to figure out.) > >>> > >>> Tuukka Tikkanen (7): > >>> Cpuidle: rename expected_us to next_timer_us in menu governor > >>> Cpuidle: Use actual state latency in menu governor > >>> Cpuidle: Ensure menu coefficients stay within domain > >>> Cpuidle: Do not substract exit latency from assumed sleep length > >>> Cpuidle: Move perf multiplier calculation out of the selection loop > >>> Cpuidle: Deal with timer expiring in the past > >>> Cpuidle: poll state can measure residency > >>> > >>> drivers/cpuidle/driver.c | 2 +- > >>> drivers/cpuidle/governors/menu.c | 85 > >>> ++++++++++++++++++++++++-------------- > >>> 2 files changed, 54 insertions(+), 33 deletions(-) > >> > >> I'm queuing this series up for 3.15. > > > > Patch [6/7] dropped, because of the Len's objection. > > Did a replacement for patch 6/7 (fix the timer code so it > does not return a negative expiry time) get written and > merged somewhere? :)
Not that I know of. > I have been looking at the menu governor too recently, > but at a different aspect. I'll send out an RFC patch > soon (which will probably be shot down, and start > a discussion). OK -- 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/
