Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755248AbaFBQWo (ORCPT ); Mon, 2 Jun 2014 12:22:44 -0400 Received: from mga03.intel.com ([143.182.124.21]:32832 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752621AbaFBQWl convert rfc822-to-8bit (ORCPT ); Mon, 2 Jun 2014 12:22:41 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.98,957,1392192000"; d="scan'208";a="439902018" From: "Luck, Tony" To: Steven Rostedt CC: Borislav Petkov , "Chen, Gong" , "m.chehab@samsung.com" , "linux-acpi@vger.kernel.org" , LKML Subject: RE: [PATCH 5/7 v6] trace, RAS: Add eMCA trace event interface Thread-Topic: [PATCH 5/7 v6] trace, RAS: Add eMCA trace event interface Thread-Index: AQHPeilSOyJTIZwXt0erLrK7gz6USJtWk/0AgAASiACAAAYGgIACpdkAgAAMgACAAGDh4IAAmseAgAOtDFA= Date: Mon, 2 Jun 2014 16:22:19 +0000 Message-ID: <3908561D78D1C84285E8C5FCA982C28F3282545B@ORSMSX114.amr.corp.intel.com> References: <1400142646-10127-1-git-send-email-gong.chen@linux.intel.com> <1401247938-22125-1-git-send-email-gong.chen@linux.intel.com> <1401247938-22125-2-git-send-email-gong.chen@linux.intel.com> <20140528112832.5f83c66b@gandalf.local.home> <20140528163452.GF17196@pd.tnic> <20140528125625.6f6dcf7f@gandalf.local.home> <20140530092232.GA13495@gchen.bj.intel.com> <20140530100716.GE28131@pd.tnic> <3908561D78D1C84285E8C5FCA982C28F32823D2B@ORSMSX114.amr.corp.intel.com> <20140530210759.267a854e@gandalf.local.home> In-Reply-To: <20140530210759.267a854e@gandalf.local.home> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.22.254.140] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >> All of this stuff only applies to server systems - so quibbling over >> a handful of *bytes* in an error record on a system that has tens, >> hundreds or even thousands of *gigabytes* of memory seems >> a bit pointless. > > But there's still only a limited number of bytes in the ring buffer no > matter what the system, thus we still need to quibble over it. To which I'll counter that the trace ring buffer can handle tracing of events like page faults and context switches (can't it?) that happen at a rate of thousands per second. Our eMCA records will normally happen at a rate of X per month (where X may well be less than one). If there is a storm of errors - we disable CMCI interrupts and revert to polling. We declare a "storm" as just 15 events in a second. If we switch to polling, then we won't poll faster than once per second. So worst case is that we are seeing some steady flow of events that don't quite trigger the storm detector ... about 14 events per second. -Tony -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/