From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-x241.google.com (mail-pg0-x241.google.com [IPv6:2607:f8b0:400e:c05::241]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3vxpn04XFtzDqHJ for ; Tue, 4 Apr 2017 09:52:20 +1000 (AEST) Received: by mail-pg0-x241.google.com with SMTP id 79so33068350pgf.0 for ; Mon, 03 Apr 2017 16:52:20 -0700 (PDT) Date: Tue, 4 Apr 2017 09:52:07 +1000 From: Nicholas Piggin To: Anton Blanchard Cc: benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, svaidy@linux.vnet.ibm.com, ego@linux.vnet.ibm.com, rjw@rjwysocki.net, daniel.lezcano@linaro.org, linuxppc-dev@lists.ozlabs.org, linux-pm@vger.kernel.org Subject: Re: [PATCH 1/3] cpuidle: powernv: Don't bounce between low and very low thread priority Message-ID: <20170404095207.28fc5229@roar.ozlabs.ibm.com> In-Reply-To: <20170403215414.16951-1-anton@ozlabs.org> References: <20170403215414.16951-1-anton@ozlabs.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, 4 Apr 2017 07:54:12 +1000 Anton Blanchard wrote: > From: Anton Blanchard > > The core of snooze_loop() continually bounces between low and very > low thread priority. Changing thread priorities is an expensive > operation that can negatively impact other threads on a core. > > All CPUs that can run PowerNV support very low priority, so we can > avoid the change completely. This looks good. I have HMT_lowest() which does alt feature patching we can use for pseries and default idle code.