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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 2131CC10DCE for ; Thu, 12 Mar 2020 22:21:01 +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 F0EB320637 for ; Thu, 12 Mar 2020 22:21:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F0EB320637 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 52C856EB45; Thu, 12 Mar 2020 22:20:59 +0000 (UTC) Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by gabe.freedesktop.org (Postfix) with ESMTPS id D2A1B6EB45 for ; Thu, 12 Mar 2020 22:20:55 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 12 Mar 2020 15:20:55 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,546,1574150400"; d="scan'208";a="237003977" Received: from adixit-mobl.amr.corp.intel.com (HELO adixit-arch.intel.com) ([10.251.157.219]) by orsmga008.jf.intel.com with ESMTP; 12 Mar 2020 15:20:54 -0700 Date: Thu, 12 Mar 2020 15:20:53 -0700 Message-ID: <87sgidw6yi.wl-ashutosh.dixit@intel.com> From: "Dixit, Ashutosh" To: Lionel Landwerlin In-Reply-To: References: <20200303221905.25866-1-umesh.nerlige.ramappa@intel.com> <20200303221905.25866-5-umesh.nerlige.ramappa@intel.com> <87tv2twezu.wl-ashutosh.dixit@intel.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM/1.14.9 (=?ISO-8859-4?Q?Goj=F2?=) APEL/10.8 EasyPG/1.0.0 Emacs/26 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Subject: Re: [Intel-gfx] [PATCH 4/7] drm/i915/perf: add new open param to configure polling of OA buffer X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: intel-gfx@lists.freedesktop.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Thu, 12 Mar 2020 13:37:12 -0700, Lionel Landwerlin wrote: > On 12/03/2020 21:27, Dixit, Ashutosh wrote: > > On Tue, 03 Mar 2020 14:19:02 -0800, Umesh Nerlige Ramappa wrote: > >> From: Lionel Landwerlin > >> > >> This new parameter let's the application choose how often the OA > >> buffer should be checked on the CPU side for data availability. Longer > >> polling period tend to reduce CPU overhead if the application does not > >> care about somewhat real time data collection. > >> > >> v2: Allow disabling polling completely with 0 value (Lionel) > >> v3: Version the new parameter (Joonas) > >> v4: Rebase (Umesh) > > Hi Lionel, I was thinking that one way to keep things simple for now (and > > fix the high cpu usage issue) would be to expose _ONLY_ this OA poll period > > parameter to user space. That is we don't expose the interrupt or the flush > > ioctl to user space at this time. This way the user will be able to > > configure the hrtimer frequency to a lower value to bring down the cpu > > usage. > > > > Also we would disallow disabling the timer (and internally also not use the > > interrupt). So everything will happen in exactly the same way as it used to > > (no other changes needed) but at a lower rate if the user so chooses. > > > > What do you think about this? > > > > Thanks! > > -- > > Ashutosh > > Sure, just make sure the users know about this. Ok, so the plan now is to just post and review/merge the first 4 patches mostly as is, except that the poll timer cannot be disabled. IMO this should solve the cpu usage issue. Then we can take up the remaining 3 interrupt and flush patches and see if they are really needed and move them forward if they are. > The fact that they can now select timer values that will potentially lead > to the loss of the buffer's data because it was overridden. I think you mean over-written. You are right but I think there is way around this and we can post that patch soon which I think will avoid this issue too. Thanks! -- Ashutosh _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx