On Sat, Jan 07, 2017 at 09:38:36PM +0100, Samuel Thibault wrote: > Hello, > > Please backport > commit ab522e33f91799661aad47bebb691f241a9f6bb8 > ('sched/fair: Fix fixed point arithmetic width for shares and effective load') > to 4.8. As 4.8-stable is about to go end-of-life on Monday (tomorrow), can't you just use 4.9 instead? > It was apparently not backported as of 4.8.16, while it fixes a huge > performance regression in our tests, see the graphs between 19320.5 and > 19451.5 on > > http://starpu.gforge.inria.fr/testing/trunk/benchmarks/tasks_size_overhead_total_lws-200.png > > which happened to be using a kernel without this fix. > > FTR, here is the patch again. > > Samuel > > commit ab522e33f91799661aad47bebb691f241a9f6bb8 > Author: Dietmar Eggemann <dietmar.eggemann@xxxxxxx> > Date: Mon Aug 22 15:00:41 2016 +0100 > > sched/fair: Fix fixed point arithmetic width for shares and effective load > > Since commit: > > 2159197d6677 ("sched/core: Enable increased load resolution on 64-bit kernels") > > we now have two different fixed point units for load: > > - 'shares' in calc_cfs_shares() has 20 bit fixed point unit on 64-bit > kernels. Therefore use scale_load() on MIN_SHARES. > > - 'wl' in effective_load() has 10 bit fixed point unit. Therefore use > scale_load_down() on tg->shares which has 20 bit fixed point unit on > 64-bit kernels. > > Signed-off-by: Dietmar Eggemann <dietmar.eggemann@xxxxxxx> > Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> > Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> > Cc: Mike Galbraith <efault@xxxxxx> > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Link: http://lkml.kernel.org/r/1471874441-24701-1-git-send-email-dietmar.eggemann@xxxxxxx > Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> I would need an ack from the developers of the patch before I could take this into a stable kernel, but again, it's a bit late for 4.8, so I don't think we should worry about it anymore, do you? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html