Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933606AbWLFPH5 (ORCPT ); Wed, 6 Dec 2006 10:07:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933843AbWLFPH5 (ORCPT ); Wed, 6 Dec 2006 10:07:57 -0500 Received: from mout2.freenet.de ([194.97.50.155]:47382 "EHLO mout2.freenet.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933835AbWLFPH4 (ORCPT ); Wed, 6 Dec 2006 10:07:56 -0500 From: Karsten Wiese To: Ingo Molnar Subject: [PATCH -rt 0/3] Make trace_freerunning work; Take 2 Date: Wed, 6 Dec 2006 16:08:24 +0100 User-Agent: KMail/1.9.5 Cc: linux-kernel@vger.kernel.org References: <20061205220257.1AECF3E2420@elvis.elte.hu> <20061205221046.GB20587@elte.hu> In-Reply-To: <20061205221046.GB20587@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200612061608.24556.fzu@wemgehoertderstaat.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1444 Lines: 39 Am Dienstag, 5. Dezember 2006 23:10 schrieb Ingo Molnar: > > freerunning should behave the same way with regard to latency > measurement. I.e. report_latency() is still needed, and the kernel will > thus do a maximum search over all traces triggered via start/stop. > > the difference is in the recording of the last-largest-latency: > > - with !freerunning, the tracer stops recording after MAX_TRACE entries, > i.e. the "head" of the trace is preserved in the trace buffer. > > - with freerunning, the tracer never stops, it 'wraps around' after > MAX_TRACE entries and starts overwriting the oldest entries. I.e. the > "tail" of the trace is preserved in the trace buffer. > > depending on the situation, freerunning or !freerunning might be the > more useful mode. > > but there should be no difference in measurement. Following 3 patches try to implement the above. Tested on a UP only after this incantation: echo 0 > /proc/sys/kernel/wakeup_timing echo 1 > /proc/sys/kernel/trace_enabled echo 1 > /proc/sys/kernel/trace_user_triggered and for half of tests: echo 1 > /proc/sys/kernel/trace_freerunning or echo 0 > /proc/sys/kernel/trace_freerunning . Karsten - 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/