Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751357AbZL1NEM (ORCPT ); Mon, 28 Dec 2009 08:04:12 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751026AbZL1NEM (ORCPT ); Mon, 28 Dec 2009 08:04:12 -0500 Received: from bombadil.infradead.org ([18.85.46.34]:36901 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750913AbZL1NEL (ORCPT ); Mon, 28 Dec 2009 08:04:11 -0500 Subject: Re: perf: counter and event question From: Peter Zijlstra To: Tim Blechmann Cc: linux-kernel@vger.kernel.org In-Reply-To: <4B38A707.4060904@klingt.org> References: <4B389391.8050303@klingt.org> <1261999573.7135.83.camel@laptop> <4B38A707.4060904@klingt.org> Content-Type: text/plain; charset="UTF-8" Date: Mon, 28 Dec 2009 14:03:33 +0100 Message-ID: <1262005413.7135.98.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 857 Lines: 22 On Mon, 2009-12-28 at 13:39 +0100, Tim Blechmann wrote: > On 12/28/2009 12:26 PM, Peter Zijlstra wrote: > > On Mon, 2009-12-28 at 12:16 +0100, Tim Blechmann wrote: > >> like it is impossible to sample instructions with a period of 1? > > > > Pretty much, imagine the cpu getting a trap every cycle. > > is this a hardware restriction? a slowdown is acceptable for me, as long > as i am able to collect a huge number of samples accurately ... Large number of samples and sample interval are only related through the runtime of your application. Use a sensible period (~10k ins) and run a 'little' longer. -- 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/