Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752426Ab3CRNSO (ORCPT ); Mon, 18 Mar 2013 09:18:14 -0400 Received: from mail-qa0-f41.google.com ([209.85.216.41]:45880 "EHLO mail-qa0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750985Ab3CRNSM (ORCPT ); Mon, 18 Mar 2013 09:18:12 -0400 MIME-Version: 1.0 In-Reply-To: <1363612263.22553.12.camel@laptop> References: <20130318124847.GA2491@quad> <1363611569.22553.10.camel@laptop> <1363612263.22553.12.camel@laptop> Date: Mon, 18 Mar 2013 14:18:12 +0100 Message-ID: Subject: Re: [PATCH] perf: fix ring_buffer perf_output_space() boundary calculation From: Stephane Eranian To: Peter Zijlstra Cc: LKML , "mingo@elte.hu" , Jiri Olsa , =?UTF-8?B?RnLDqWTDqXJpYyBXZWlzYmVja2Vy?= Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1241 Lines: 29 On Mon, Mar 18, 2013 at 2:11 PM, Peter Zijlstra wrote: > On Mon, 2013-03-18 at 14:03 +0100, Stephane Eranian wrote: >> On Mon, Mar 18, 2013 at 1:59 PM, Peter Zijlstra wrote: >> > On Mon, 2013-03-18 at 13:48 +0100, Stephane Eranian wrote: >> >> if (!rb->writable) >> >> - return true; >> >> + return false; >> > >> > >> > writable means user writable (VM_WRITE); the difference is that a >> > !VM_WRITE buffer will simply over-write its own tail whereas a VM_WRITE >> > buffer will drop events. >> > >> > So returning true for !VM_WRITE makes sense, there's always space. >> > >> Ok, that was not so clear to me. I think this if() statment deserves a comment. >> I will add that in V2. > > Thanks; I suppose renaming the entire ->writable thing might be better > though. Something like ->overwrite or so. > Yes. And if you do this you invert the logic of the field. overwrite=1 -> !VM_WRITE overwrite=0 -> VM_WRITE -- 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/