From patchwork Mon Apr 3 21:54:12 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anton Blanchard X-Patchwork-Id: 746666 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [103.22.144.68]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3vxmB92kT6z9s7n for ; Tue, 4 Apr 2017 07:55:29 +1000 (AEST) Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 3vxmB9200PzDqJl for ; Tue, 4 Apr 2017 07:55:29 +1000 (AEST) X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3vxm8z5DNCzDqGr for ; Tue, 4 Apr 2017 07:54:27 +1000 (AEST) Received: by ozlabs.org (Postfix, from userid 1010) id 3vxm8z4XVhz9s7r; Tue, 4 Apr 2017 07:54:27 +1000 (AEST) From: Anton Blanchard To: 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, npiggin@gmail.com Subject: [PATCH 1/3] cpuidle: powernv: Don't bounce between low and very low thread priority Date: Tue, 4 Apr 2017 07:54:12 +1000 Message-Id: <20170403215414.16951-1-anton@ozlabs.org> X-Mailer: git-send-email 2.11.0 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, linux-pm@vger.kernel.org Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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. Signed-off-by: Anton Blanchard Reviewed-by: Vaidyanathan Srinivasan --- drivers/cpuidle/cpuidle-powernv.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c index cda8f62d555b..9d9f164894eb 100644 --- a/drivers/cpuidle/cpuidle-powernv.c +++ b/drivers/cpuidle/cpuidle-powernv.c @@ -57,7 +57,6 @@ static int snooze_loop(struct cpuidle_device *dev, snooze_exit_time = get_tb() + snooze_timeout; ppc64_runlatch_off(); while (!need_resched()) { - HMT_low(); HMT_very_low(); if (snooze_timeout_en && get_tb() > snooze_exit_time) break;