From patchwork Tue Oct 26 11:40:51 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sebastian Andrzej Siewior X-Patchwork-Id: 12584673 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C6A02C433EF for ; Tue, 26 Oct 2021 11:41:23 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9777460D07 for ; Tue, 26 Oct 2021 11:41:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 9777460D07 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id DD8246E595; Tue, 26 Oct 2021 11:41:08 +0000 (UTC) Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by gabe.freedesktop.org (Postfix) with ESMTPS id 2D5986E563; Tue, 26 Oct 2021 11:41:07 +0000 (UTC) From: Sebastian Andrzej Siewior DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1635248465; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=LA+90sHRZNpkk1aLLF2Masb7U0Mao+Pu/ydbc5UfYUo=; b=r4yecKMV13TAA5Va4ZX+PhCLo3gzrWGlIHu4dAd/1O8YnYc+sALWmeD99zk+v0iM+huwgV cDX7LHLpVvVAj9BQHefGXAQFEPkTLBkKqrRQ1FsHLnj2H/E1s3f5R7sKybtbF1CcbulsRR CMyLw2brqdByTzkYlmAewRZ9VYuy1uXywkLnbuy6dwiBYzXtvcfQv9JYyUSuUffVERfhly Gc77GKBouQ+YvGPD5bGSAZ0h9xrf/ZAsJ4fYxBaqBUUSBd7wNfx/5VePxN/JuJQZ3Ox6Ef hVRhZedMsU5Q1K+Y/kyXVEBvT2aAPHxB2rPU9PBW8Oy0oo9WqUDH7mbXNMZmog== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1635248465; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=LA+90sHRZNpkk1aLLF2Masb7U0Mao+Pu/ydbc5UfYUo=; b=ZH4PmHt50tqJOByqB3AB7KqMqdVo51sZAkdXShFANH/gSQASkCvkBM39Prav/cTzRwG4Vu +gZWcNVxnFWcIXAg== To: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Cc: Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , David Airlie , Daniel Vetter , Thomas Gleixner , Peter Zijlstra Subject: [PATCH v2 0/9] drm/i915: PREEMPT_RT related fixups. Date: Tue, 26 Oct 2021 13:40:51 +0200 Message-Id: <20211026114100.2593433-1-bigeasy@linutronix.de> MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" the following patches are from the PREEMPT_RT queue. It is mostly about disabling interrupts/preemption which leads to problems. Patches 1-4 are independent of PREEMPT_RT. Unfortunately DRM_I915_LOW_LEVEL_TRACEPOINTS had to be disabled because it acquires locks from within trace points. It has been pointed out in the previous post that this makes any kind of debugging impossible. Making the uncore.lock a raw_spinlock_t doubles the latencies in my limited testing [0]. I don't know the difference on other hardware. Also it worries me a little that wait_for_atomic() has 50ms as the upper spin/wait limit if the condition does not become true. I tested it on a SandyBridge with built-in i915 by using X, OpenGL and playing videos without noticing any warnings. However, some code paths were not entered. [0] https://lore.kernel.org/all/20211006164628.s2mtsdd2jdbfyf7g@linutronix.de/ Sebastian