Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752335Ab1CTTtX (ORCPT ); Sun, 20 Mar 2011 15:49:23 -0400 Received: from sj-iport-5.cisco.com ([171.68.10.87]:39869 "EHLO sj-iport-5.cisco.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752240Ab1CTTtV (ORCPT ); Sun, 20 Mar 2011 15:49:21 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AvsEABX3hU2tJV2d/2dsb2JhbAClbXeITZsxmw+CfoJlBIUzhzSDUQ X-IronPort-AV: E=Sophos;i="4.63,216,1299456000"; d="scan'208";a="349378082" Message-ID: <4D865A3E.9040605@cisco.com> Date: Sun, 20 Mar 2011 13:49:18 -0600 From: David Ahern User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.13) Gecko/20101209 Fedora/3.1.7-0.35.b3pre.fc14 Thunderbird/3.1.7 MIME-Version: 1.0 To: Thomas Gleixner CC: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, acme@ghostprotocols.net, mingo@elte.hu, peterz@infradead.org, fweisbec@gmail.com, paulus@samba.org Subject: Re: [PATCH 1/5] perf events: add support for realtime clock attribute References: <1300647277-8431-1-git-send-email-daahern@cisco.com> <1300647277-8431-2-git-send-email-daahern@cisco.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 802 Lines: 27 On 03/20/11 13:08, Thomas Gleixner wrote: > On Sun, 20 Mar 2011, David Ahern wrote: >> + >> + if (sample_type & PERF_SAMPLE_REALTIME) >> + data->realtime = ktime_to_ns(ktime_get_real()); > > That's going to live lock on any sample which happens to hit in a > xtime_lock write locked section. I knew why I suggested adding > tracepoints to the timekeeping code :) Hmmm.... Can you give an example of when perf samples could be generated with xtime write locked? What are the rules for when ktime_get_real can be invoked? David > > Thanks, > > tglx -- 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/