Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753514AbbHCNFn (ORCPT ); Mon, 3 Aug 2015 09:05:43 -0400 Received: from mail-wi0-f182.google.com ([209.85.212.182]:36044 "EHLO mail-wi0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751982AbbHCNFm (ORCPT ); Mon, 3 Aug 2015 09:05:42 -0400 Date: Mon, 3 Aug 2015 15:05:37 +0200 From: Frederic Weisbecker To: Peter Zijlstra Cc: LKML , Thomas Gleixner , Preeti U Murthy , Christoph Lameter , Ingo Molnar , Viresh Kumar , Rik van Riel Subject: Re: [PATCH 05/10] nohz: New tick dependency mask Message-ID: <20150803130535.GC20269@lerouge> References: <1437669735-8786-1-git-send-email-fweisbec@gmail.com> <1437669735-8786-6-git-send-email-fweisbec@gmail.com> <20150803124350.GH19282@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150803124350.GH19282@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1670 Lines: 36 On Mon, Aug 03, 2015 at 02:43:50PM +0200, Peter Zijlstra wrote: > On Thu, Jul 23, 2015 at 06:42:10PM +0200, Frederic Weisbecker wrote: > > +unsigned long __tick_nohz_set_tick_dependency(enum tick_dependency_bit bit, > > + unsigned long *dep) > > +{ > > + unsigned long prev; > > + unsigned long old = *dep; > > + unsigned long mask = BIT_MASK(bit); > > + > > + while ((prev = cmpxchg(dep, old, old | mask)) != old) { > > + old = prev; > > + cpu_relax(); > > + } > > + > > + return prev; > > +} > > That's typically called a fetch_or(). The function name, which is > entirely too long, also doesn't suggest a return value. Nice, I can export fetch_or() from sched code to atomic_fetch_or() like you just suggested and bring it to asm_generic if you like. Although given that function name, I fear some people may miss it when they need such a functionality. I mean, people are interested in a test_and_set_bit() that returns the whole value. test_and_or() would better recall the test_and_set() under the line. Now perhaps "test" rather suggests we are dealing with a mask test. So perhaps fetch_and_or() ? Of course having "and" then "or" in the same function name might be confusing but after all we have functions names starting with "test" then "and". Concerning the nohz function name, tick_nohz is a long prefix that is very likely to produce too long names. Perhaps I should trim tick_nohz to just nohz. -- 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/