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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 5288EFCA17A for ; Mon, 9 Mar 2026 18:55:58 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 9C72310E58D; Mon, 9 Mar 2026 18:55:57 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=sina.com header.i=@sina.com header.b="ymqM37cY"; dkim-atps=neutral X-Greylist: delayed 323 seconds by postgrey-1.36 at gabe; Thu, 05 Mar 2026 23:15:25 UTC Received: from r3-23.sinamail.sina.com.cn (r3-23.sinamail.sina.com.cn [202.108.3.23]) by gabe.freedesktop.org (Postfix) with ESMTPS id 6291D10EC85 for ; Thu, 5 Mar 2026 23:15:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sina.com; s=201208; t=1772752525; bh=Shl+BiZngOGxg1GDTZ6fLo/PO0+5Oaw5mzBqiPTjjjQ=; h=From:Subject:Date:Message-ID; b=ymqM37cYXL5cx2FbwSffTjCRopCatOi5pDbD1+TwGtL+RJA//7UyXXl67ldUXzqZA M8GSqqTE/IoaVUWp/nKCs1PsqecK6QCzlwED0Vj6Fp3evZW1Q5dFDnPFzBhKlLupmH MmQOPgGvamdAXpow/y7pHcb4Fc0i6cJlaCpoexqE= X-SMAIL-HELO: localhost.localdomain Received: from unknown (HELO localhost.localdomain)([114.249.62.144]) by sina.com (10.54.253.31) with ESMTP id 69AA0D4600005D81; Thu, 6 Mar 2026 07:09:59 +0800 (CST) X-Sender: hdanton@sina.com X-Auth-ID: hdanton@sina.com Authentication-Results: sina.com; spf=none smtp.mailfrom=hdanton@sina.com; dkim=none header.i=none; dmarc=none action=none header.from=hdanton@sina.com X-SMAIL-MID: 3628436816224 X-SMAIL-UIID: 0D0675C103F64A02951E9EFE8FA1D363-20260306-070959-1 From: Hillf Danton To: Chia-I Wu Cc: Matthew Brost , DRI , intel-xe@lists.freedesktop.org, Danilo Krummrich , Philipp Stanner , Boris Brezillon , LKML Subject: Re: drm_sched run_job and scheduling latency Date: Fri, 6 Mar 2026 07:09:46 +0800 Message-ID: <20260305230948.679-1-hdanton@sina.com> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit X-Mailman-Approved-At: Mon, 09 Mar 2026 18:55:56 +0000 X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" On Wed, Mar 04, 2026 at 02:51:39PM -0800, Chia-I Wu wrote: > Hi, > > Our system compositor (surfaceflinger on android) submits gpu jobs > from a SCHED_FIFO thread to an RT gpu queue. However, because > workqueue threads are SCHED_NORMAL, the scheduling latency from submit > to run_job can sometimes cause frame misses. We are seeing this on > panthor and xe, but the issue should be common to all drm_sched users. > > Using a WQ_HIGHPRI workqueue helps, but it is still not RT (and won't > meet future android requirements). It seems either workqueue needs to > gain RT support, or drm_sched needs to support kthread_worker. > As RT means (in general) to some extent that the game of eevdf is played in __userspace__, but you are not PeterZ, so any issue like frame miss is understandably expected. Who made the workqueue worker a victim if the CPU cycles are not tight? Who is the new victim of a RT kthread worker? As RT is not free, what did you pay for it, given fewer RT success on market?