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=-8.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 A067BC63798 for ; Fri, 27 Nov 2020 14:40:36 +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 20E2E21D81 for ; Fri, 27 Nov 2020 14:40:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 20E2E21D81 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=chris-wilson.co.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 213B36EE03; Fri, 27 Nov 2020 14:40:35 +0000 (UTC) Received: from fireflyinternet.com (unknown [77.68.26.236]) by gabe.freedesktop.org (Postfix) with ESMTPS id 108DF6EDFD; Fri, 27 Nov 2020 14:40:32 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from localhost (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP (TLS) id 23134491-1500050 for multiple; Fri, 27 Nov 2020 14:40:29 +0000 MIME-Version: 1.0 In-Reply-To: <20201127120718.454037-158-matthew.auld@intel.com> References: <20201127120718.454037-1-matthew.auld@intel.com> <20201127120718.454037-158-matthew.auld@intel.com> Subject: Re: [Intel-gfx] [RFC PATCH 157/162] drm/i915: Improve accuracy of eviction stats From: Chris Wilson To: Matthew Auld , intel-gfx@lists.freedesktop.org Date: Fri, 27 Nov 2020 14:40:28 +0000 Message-ID: <160648802888.2925.2681758176898405257@build.alporthouse.com> User-Agent: alot/0.9 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: , Cc: dri-devel@lists.freedesktop.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Quoting Matthew Auld (2020-11-27 12:07:13) > From: Tvrtko Ursulin > > Current code uses jiffie time to do the accounting and then does: > > diff = jiffies - start; > msec = diff * 1000 / HZ; > ... > atomic_long_add(msec, &i915->time_swap_out_ms); > > If we assume jiffie can be as non-granular as 10ms and that the current > accounting records all evictions faster than one jiffie as infinite speed, > we can end up over-estimating the reported eviction throughput. > > Fix this by accumulating ktime_t and only dividing to more user friendly > granularity at presentation time (debugfs read). > > At the same time consolidate the code a bit and convert from multiple > atomics to single seqlock per stat. > > Signed-off-by: Tvrtko Ursulin > Cc: CQ Tang > Cc: Sudeep Dutt > Cc: Mika Kuoppala A lot of effort to fix up patches after the fact, might as well make it a real PMU interface. -Chris _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel