From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 16878C3A5A2 for ; Tue, 3 Sep 2019 13:09:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E71942341E for ; Tue, 3 Sep 2019 13:09:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729295AbfICNJe convert rfc822-to-8bit (ORCPT ); Tue, 3 Sep 2019 09:09:34 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:60192 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729119AbfICNJd (ORCPT ); Tue, 3 Sep 2019 09:09:33 -0400 Received: from bigeasy by Galois.linutronix.de with local (Exim 4.80) (envelope-from ) id 1i58Ys-0000gh-Mb; Tue, 03 Sep 2019 15:09:30 +0200 Date: Tue, 3 Sep 2019 15:09:30 +0200 From: Sebastian Andrzej Siewior To: Clark Williams Cc: bigeasy@linutronix.com, tglx@linutronix.com, linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PREEMPT_RT PATCH 2/3] i915: convert all irq_locks spinlocks to raw spinlocks Message-ID: <20190903130930.isctetjvzckgubuh@linutronix.de> References: <20190820003319.24135-1-clark.williams@gmail.com> <20190820003319.24135-3-clark.williams@gmail.com> <20190903080335.pe45dmgmjvdvbyd4@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8BIT In-Reply-To: <20190903080335.pe45dmgmjvdvbyd4@linutronix.de> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019-09-03 10:03:35 [+0200], To Clark Williams wrote: > anything in a brief test. What I saw however is that switching to > fullscreen while playing a video gives me ~0.5 to ~2ms latency. This is > has nothing to do with this change, I have to dig deeper… It might be > one of the preempt_disable() section I just noticed. > I would prefer to keep the lock non-raw unless there is actual need for > it. That latency spike is caused by the iommu, qi_submit_sync() to be exact. Without the iomm I don't see much difference between the two patches… Sebastian