Hello, On Wed, Apr 24, 2013 at 05:12:52PM +0530, Viresh Kumar wrote: > This patchset was called: "Create sched_select_cpu() and use it for workqueues" > for the first three versions. > > Earlier discussions over v3, v2 and v1 can be found here: > https://lkml.org/lkml/2013/3/18/364 > http://lists.linaro.org/pipermail/linaro-dev/2012-November/014344.html > http://www.mail-archive.com/linaro-dev@xxxxxxxxxxxxxxxx/msg13342.html > > V4 is here: > https://lkml.org/lkml/2013/3/31/55 > > Workqueues can be performance or power oriented. For performance we may want to > keep them running on a single cpu, so that it remains cache hot. For power we > can give scheduler the liberty to choose target cpu for running work handler. > > Later one (Power oriented WQ) can be achieved if the workqueue is allocated with > WQ_UNBOUND flag. Enabling CONFIG_WQ_POWER_EFFICIENT will set > 'wq_power_efficient' to 'true'. Setting 'power_efficient' boot param will > override value of 'wq_power_efficient' variable. When 'wq_power_efficient' is > set to 'true', we will convert WQ_POWER_EFFICIENT flag to WQ_UNBOUND on wq > allocation. And so scheduler will have the liberty to choose where to run this > work. > > Here we are migrating few users of workqueues to WQ_POWER_EFFICIENT. These > drivers are found to be very much active on idle or lightly busy system and > using WQ_POWER_EFFICIENT for these gave impressive results. > > These would be used in power saving mode only if relevant configs are enabled > at compile time or in bootargs. Otherwise behavior is unchanged. > > Setup: > ----- > - ARM Vexpress TC2 - big.LITTLE CPU > - Core 0-1: A15, 2-4: A7 > - rootfs: linaro-ubuntu-devel This patch set hit my tree now. I wonder if it makes sense to make WQ_POWER_EFFICIENT_DEFAULT depend on SMP. (Oh wait, big.LITTLE isn't SMP, so probably there is a better symbol to depend on?) Just my 2 cent Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
