Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758011Ab1EaHXW (ORCPT ); Tue, 31 May 2011 03:23:22 -0400 Received: from casper.infradead.org ([85.118.1.10]:48295 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752769Ab1EaHXV convert rfc822-to-8bit (ORCPT ); Tue, 31 May 2011 03:23:21 -0400 Subject: Re: perf: [patch] regression with PERF_EVENT_IOC_REFRESH From: Peter Zijlstra To: Vince Weaver Cc: Vince Weaver , linux-kernel@vger.kernel.org, mingo@elte.hu, paulus@samba.org, acme@redhat.com In-Reply-To: References: <1306182141.2497.5.camel@laptop> <1306233036.2497.15.camel@laptop> <1306578144.1200.1150.camel@twins> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Tue, 31 May 2011 09:23:13 +0200 Message-ID: <1306826593.2530.7.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 869 Lines: 21 On Mon, 2011-05-30 at 21:33 -0400, Vince Weaver wrote: > the problem was the mentioned commit tried to optimize the use of > watermark and wakeup_watermark without taking into account that > wakeup_watermark is a union with wakeup_events. Note that wake_events isn't related to IOC_REFRESH, wake_events is how much events to buffer in the mmap-buffer before issuing a wakeup. IOC_REFRESH increments event_limit, which is how many events to run before disabling yourself. What I gather is that due to that SIGIO bug (fixed by f506b3dc0e), you had to have both an mmap and a wakeup in order for that signal to arrive. -- 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/