Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753714AbbHCNJs (ORCPT ); Mon, 3 Aug 2015 09:09:48 -0400 Received: from mail-wi0-f171.google.com ([209.85.212.171]:32933 "EHLO mail-wi0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753693AbbHCNJp (ORCPT ); Mon, 3 Aug 2015 09:09:45 -0400 Date: Mon, 3 Aug 2015 15:09:39 +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: <20150803130938.GD20269@lerouge> References: <1437669735-8786-1-git-send-email-fweisbec@gmail.com> <1437669735-8786-6-git-send-email-fweisbec@gmail.com> <20150803125717.GJ19282@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150803125717.GJ19282@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: 2144 Lines: 77 On Mon, Aug 03, 2015 at 02:57:17PM +0200, Peter Zijlstra wrote: > On Thu, Jul 23, 2015 at 06:42:10PM +0200, Frederic Weisbecker wrote: > > +void tick_nohz_set_tick_dependency(enum tick_dependency_bit bit) > > +{ > > + unsigned long prev; > > + > > + prev = __tick_nohz_set_tick_dependency(bit, &tick_dependency); > > + if (!prev) > > + tick_nohz_full_kick_all(); > > +} > > > +void tick_nohz_set_tick_dependency_cpu(enum tick_dependency_bit bit, int cpu) > > +{ > > + unsigned long prev; > > + struct tick_sched *ts; > > + > > + ts = per_cpu_ptr(&tick_cpu_sched, cpu); > > + > > + prev = __tick_nohz_set_tick_dependency(bit, &ts->tick_dependency); > > + if (!prev) > > + tick_nohz_full_kick_cpu(cpu); > > +} > > > +/* > > + * Local dependency must have its own flavour due to NMI-safe requirement > > + * on perf. > > + */ > > That doesn't make any sense: > > tick_nohz_set_tick_dependency_this_cpu(); > > (shees, you're nowhere near lazy enough, that's insane to type) is > almost identical to: > > tick_nohz_set_tick_dependency_cpu(.cpu = smp_processor_id()); > > The only difference is a _very_ slight reduction in cost for computing > the per-cpu offset. But the local one must be NMI-safe. Now I can do: if (cpu == smp_processor_id()) tick_nohz_full_kick() // NMI-safe else tick_nohz_full_kick_cpu(cpu); // not NMI-safe. > > > +void tick_nohz_set_tick_dependency_this_cpu(enum tick_dependency_bit bit) > > +{ > > + unsigned long prev; > > + struct tick_sched *ts; > > + > > + ts = this_cpu_ptr(&tick_cpu_sched); > > + > > + prev = __tick_nohz_set_tick_dependency(bit, &ts->tick_dependency); > > + if (!prev) > > + tick_nohz_full_kick(); > > +} > > > And on that naming; could we please shorten them, this is really > ridiculous, it has 'tick' in it twice. > > What's wrong with: > > tick_nohz_set_dep() > tick_nohz_set_dep_cpu() Right. Thanks. -- 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/