From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.11]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C0D501DDC0B; Thu, 21 Aug 2025 01:51:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755741105; cv=none; b=jkmeYjzO45vSjIHrSQdpjh9LJyG+rjfXZE6GtqNYW338nYuW2VyFFYdM3fRnDe0eCDOTKoJapun4ItXW7hz2PpcGzraYQvkPHbOJcu1qiNZUYDrS69NUwGoNaFwj0Fi4B6DJ3OPjTrzyARNXdO3rqnP0Egn75jDdUO8JqurMk3c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755741105; c=relaxed/simple; bh=4AKDPWqATzK1Hsj9qLvg8hUknNHF8JNcg5P0w4J1UCE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=FZ1eyob5gFkHuglZGY+/XE73K8Yf24w87wLhTQGU2/ibVcmMcf5KNGLfwoYsRU6EFkIxndbGd47UfMfdKWVWbb7kHDOLP2dsifJATrxkJkEaUfD0mkpa8lFJFWbtPiGjlqD3W2j/qqwjPT4KSDh9pV10YwPi/t5pdp1MJ4+xMIE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=GzJwQksa; arc=none smtp.client-ip=198.175.65.11 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="GzJwQksa" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1755741103; x=1787277103; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=4AKDPWqATzK1Hsj9qLvg8hUknNHF8JNcg5P0w4J1UCE=; b=GzJwQksaBjxw8jVF9vcnhokpRnwQoReT6ZN50z5NE95REMVl+GtSaC0y uuwguJuAOeKG0k/aM7IQNxa4GxsminkXWVT8mczmdyQq9G2Inif8s6toJ QKGvYo0r+lCF0LP2XORXQJoQ7f1AOvAEzRwuzx4hqWnYYZvk97OaT9QVo 8A/lonHwL4M8sX1PIh3goxVP/Z33XXiebAgKiVPZtgfC2+ZQw423PQ8Rm 8xK7iWVDaQwQJ97KPQfKtPPyvxVpgj8ZuSS0GdQ4t2T+jgm198hn5Jfix ZkeRQM0W1qrwoZvHijtg5HyPNZtXJ9Ax6SbVA3rlpSE4ES53++OVmOQIB w==; X-CSE-ConnectionGUID: bI4kJQrYQEmVw7iXpawabQ== X-CSE-MsgGUID: Js1e3nMtQxOOFWzgy/Sg2A== X-IronPort-AV: E=McAfee;i="6800,10657,11527"; a="68290614" X-IronPort-AV: E=Sophos;i="6.17,306,1747724400"; d="scan'208";a="68290614" Received: from orviesa008.jf.intel.com ([10.64.159.148]) by orvoesa103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Aug 2025 18:51:40 -0700 X-CSE-ConnectionGUID: T8b1BdI7TIiBzajZQD/6hA== X-CSE-MsgGUID: AWjOEuNzQ7mcc38JzYs6WA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.17,306,1747724400"; d="scan'208";a="168537534" Received: from tassilo.jf.intel.com (HELO tassilo) ([10.54.38.190]) by orviesa008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Aug 2025 18:51:33 -0700 Date: Wed, 20 Aug 2025 18:51:30 -0700 From: Andi Kleen To: "Mi, Dapeng" Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Ian Rogers , Adrian Hunter , Alexander Shishkin , Kan Liang , Eranian Stephane , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Dapeng Mi , kernel test robot Subject: Re: [Patch v3 3/7] perf/x86: Check if cpuc->events[*] pointer exists before accessing it Message-ID: References: <20250820023032.17128-1-dapeng1.mi@linux.intel.com> <20250820023032.17128-4-dapeng1.mi@linux.intel.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Aug 20, 2025 at 01:54:17PM +0800, Mi, Dapeng wrote: > > On 8/20/2025 1:44 PM, Andi Kleen wrote: > >> Andi, I didn't fully get the exact meaning about the "log" here. When > >> throttle is triggered, perf_event_throttle() has already called > >> perf_log_throttle() to log the throttle event although only for the group > >> leader. Is it enough? > > Throttle normally doesn't involve data loss, just less samples. But this > > is data loss, so it's an overflow. > > IIUC, there should be no data loss, the unprocessed PEBS records of these > throttled events would be still processed eventually by calling > intel_pmu_drain_pebs_buffer() when stopping the event. Makes sense. Thanks, -Andi