Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756033AbbFQBEt (ORCPT ); Tue, 16 Jun 2015 21:04:49 -0400 Received: from mail-pa0-f51.google.com ([209.85.220.51]:36292 "EHLO mail-pa0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751235AbbFQBEl (ORCPT ); Tue, 16 Jun 2015 21:04:41 -0400 Message-ID: <5580C7A7.5040705@plumgrid.com> Date: Tue, 16 Jun 2015 18:04:39 -0700 From: Alexei Starovoitov User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Steven Rostedt CC: Daniel Wagner , paulmck@linux.vnet.ibm.com, Daniel Wagner , LKML Subject: Re: call_rcu from trace_preempt References: <557F509D.2000509@plumgrid.com> <20150615230702.GB3913@linux.vnet.ibm.com> <557F7764.5060707@plumgrid.com> <20150616021458.GE3913@linux.vnet.ibm.com> <557FB7E1.6080004@plumgrid.com> <20150616122733.GG3913@linux.vnet.ibm.com> <558018DD.1080701@monom.org> <55805AC5.8020507@plumgrid.com> <20150616133709.6c53645d@gandalf.local.home> <5580C054.2080809@plumgrid.com> <20150616204711.0e6ea1d7@grimm.local.home> In-Reply-To: <20150616204711.0e6ea1d7@grimm.local.home> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 719 Lines: 16 On 6/16/15 5:47 PM, Steven Rostedt wrote: > Do what I do in tracing. Use a bit (per cpu?) test. > > Add the element to the list (that will be a cmpxchg, but I'm not sure > you can avoid it), then check the bit to see if the irq work is already > been activated. If not, then activate the irq work and set the bit. > Then you will not have any more cmpxchg in the fast path. you mean similar to what rb_wakeups() and friends are doing? makes sense. starting to study it... -- 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/