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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 896A1C4345F for ; Tue, 23 Apr 2024 15:45:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=4GyTfsZDOJFZY1FpVSe2Umt6WpmhVwTLJMOgu9+yPWQ=; b=SmLYOaW2HThqb+ /JvS6r2bu175wdywM3Y8J1TeaPb4DORdLh8b2KDNChdjY7lMLzYRxN+y8KS71K5csCM+6NuWVy94S UslFQToVC4STC2stZOp2WpqWfVe7XFXY2/kjDlxAIKDPYoT3Mcni0bq/Jt2AlOQJGP7Ju1dwxEBA1 wqkjBZ5vwMtl173V34fy47xmEQhdf9kVu28e3IwjD8X+F98yLeJ2Ipknwj4+QB7288aPLhRIS7IDP yp38w48vTph/K49NRj6hYQN00frKUOJmdyw+usbhIOtjKkpuU6/+syBMlw/aG7HY12JEz8abAFFeA rhotyjYnZa0T6MhIJZGg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rzIKZ-00000000ano-1qyW; Tue, 23 Apr 2024 15:45:15 +0000 Received: from mgamail.intel.com ([192.198.163.16]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rzIKW-00000000amo-2MnZ for linux-arm-kernel@lists.infradead.org; Tue, 23 Apr 2024 15:45:14 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1713887113; x=1745423113; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=MA9446VKnhvmz6/0EyeIfdr7SFbSysHM+adFvzkui6g=; b=TwVRIS75z8qcQD/dpNQAS0WNYBfMGMD7rofdKSuvGwfEMGMthfGGadID 9MfS6M1vC55/2YCRhLMt/aH4qE2AtzIf9cna6jdV2+qOLM38FfDdiTAkW Xq/cKB67qFvrxC1Gzr2CbBgKhjOXYqm7j28ktxUrR3CkpGweurvprFmu8 dOY/qSftChu315U08OXmnMTmbAMJZjBIo910hA5G+MGhfhBpjXRnEO2oj PfX35O11+emLi4mIxqqWoAuppCznsdfxgU9YZ9uACA+XHmimGN3QAuP26 Y4Uo+sgBm01H4AS5ND6TcmYQAZ9b3/ihcl8ViLmeClAXxhF26bdJ2ABZc w==; X-CSE-ConnectionGUID: oZTL3dQmSm+YQEX62q8PxQ== X-CSE-MsgGUID: 5F3XxuwXS2uEQoYIVtImIQ== X-IronPort-AV: E=McAfee;i="6600,9927,11053"; a="10021998" X-IronPort-AV: E=Sophos;i="6.07,222,1708416000"; d="scan'208";a="10021998" Received: from fmviesa003.fm.intel.com ([10.60.135.143]) by fmvoesa110.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Apr 2024 08:45:11 -0700 X-CSE-ConnectionGUID: mp1IFeV0RzGJ6l5msSO2OQ== X-CSE-MsgGUID: fRB2rqL4QYyVS/b1hmHg+g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,222,1708416000"; d="scan'208";a="28904442" Received: from tassilo.jf.intel.com (HELO tassilo) ([10.54.38.190]) by fmviesa003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Apr 2024 08:45:10 -0700 Date: Tue, 23 Apr 2024 08:42:42 -0700 From: Andi Kleen To: Ben Gainey Cc: peterz@infradead.org, mingo@redhat.com, acme@kernel.org, namhyung@kernel.org, will@kernel.org, james.clark@arm.com, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [RFC PATCH v2 0/4] A mechanism for efficient support for per-function metrics Message-ID: References: <20240422104929.264241-1-ben.gainey@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240422104929.264241-1-ben.gainey@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240423_084512_650219_75DF622C X-CRM114-Status: GOOD ( 12.24 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org > Cursory testing on a Xeon(R) W-2145 with a 300 *instruction* sample > window (with and without the patch) suggests this approach would work > for some counters. Calculating branch miss rates for example appears to > be correct when used with the instruction counter as the sampling event, > or at least this approach correctly identifies which functions in the > test benchmark are prone to poor predictability. On the other hand the > combination cycle and instructions counter does not appear to sample > correctly as a pair. With something like > > perf record -e '{cycles/period=999700,alt-period=300/,instructions}:uS' ... benchmark > > I often see very large CPI, the same affect is observed without the > patch enabled. No idea whats going on there, so any insight welcome... My guess would be that the PMI handler cleared L1 and there are stalls reloading the working set. You can check L1 miss events to confirm. Unfortunately with the period change it cannot use multi-record PEBS which would avoid the need for a PMI. -Andi _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel