lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Sun, 26 Oct 2014 14:58:36 +0100 From: Mike Galbraith <umgwanakikbuti@...il.com> To: "Steinar H. Gunderson" <sgunderson@...foot.com> Cc: Thomas Gleixner <tglx@...utronix.de>, Linus Torvalds <torvalds@...ux-foundation.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Peter Zijlstra <peterz@...radead.org> Subject: Re: bisected: futex regression >= 3.14 - was - Slowdown due to threads bouncing between HT cores On Sun, 2014-10-26 at 14:16 +0100, Mike Galbraith wrote: > On Sun, 2014-10-26 at 11:39 +0100, Steinar H. Gunderson wrote: > > On Fri, Oct 24, 2014 at 06:38:41PM +0200, Mike Galbraith wrote: > > >>> Whew, good, futex.c is hard. Heads up chess guys <punt>. > > >> I wonder whether the barrier fix which got into 3.17 late fixes that > > >> issue as well. > > > Yes, it did. > > > > This is only about the lockup, right, not that the threads bounce around a > > lot and make things slower? > > Yes. I couldn't reproduce your results, on my 28 core+ht box, there was > little difference between pinned/unpinned. Maybe the box was too quite, > not enough random activity to motivate select_idle_sibling(). Can you try the below? --- kernel/sched/fair.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4477,6 +4477,12 @@ static int select_idle_sibling(struct ta return i; /* + * Don't bounce hefty tasks about, they may be hitting contention. + */ + if (p->se.load.weight - (p->se.load.weight/4) < p->se.avg.load_avg_contrib) + return target; + + /* * Otherwise, iterate the domains and find an elegible idle cpu. */ sd = rcu_dereference(per_cpu(sd_llc, target)); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists