From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Galbraith Subject: Re: [RFC PATCH 0/5] futex: introduce an optimistic spinning futex Date: Wed, 23 Jul 2014 06:55:03 +0200 Message-ID: <1406091303.5076.33.camel@marge.simpson.net> References: <1405956271-34339-1-git-send-email-Waiman.Long@hp.com> <8761iq3bp3.fsf@tassilo.jf.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <8761iq3bp3.fsf-KWJ+5VKanrL29G5dvP0v1laTQe2KTcn/@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Andi Kleen Cc: Waiman Long , Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Darren Hart , Davidlohr Bueso , Heiko Carstens , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Jason Low , Scott J Norton List-Id: linux-api@vger.kernel.org On Mon, 2014-07-21 at 09:42 -0700, Andi Kleen wrote: > FWIW the main problem is currently that switch-through-idle is so > slow. I think improving that would give a boost to far more > situations. Two high frequency idle enter/exit suckage spots: 1) nohz (tick) - it's expensive to start/stop tick on every micro-idle, throttle it or something. 2) ondemand governor - tweak silly default settings to reflect the reality that we routinely schedule communicating threads cross core. (3. seek/destroy fastpath cycles, damn things multiply over time) -Mike