Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754879AbZCLFw7 (ORCPT ); Thu, 12 Mar 2009 01:52:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751238AbZCLFwv (ORCPT ); Thu, 12 Mar 2009 01:52:51 -0400 Received: from smtp-out.google.com ([216.239.33.17]:11674 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751204AbZCLFwu (ORCPT ); Thu, 12 Mar 2009 01:52:50 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id: references:user-agent:mime-version:content-type:x-system-of-record; b=xhDVZCXd86LvMpagF/Pv6BIm7tRW9p7MiSIfv7Mii9Ae9bUXiu/RrSQ+g3VAk7Gj+ rHWNv5pvSOXlFvbuejzew== Date: Wed, 11 Mar 2009 22:51:12 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: "Paul E. McKenney" cc: Christoph Lameter , Andrew Morton , Pekka Enberg , Matt Mackall , Paul Menage , Randy Dunlap , linux-kernel@vger.kernel.org Subject: Re: [patch -mm] cpusets: add memory_slab_hardwall flag In-Reply-To: <20090312010330.GK7086@linux.vnet.ibm.com> Message-ID: References: <20090312010330.GK7086@linux.vnet.ibm.com> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 936 Lines: 20 On Wed, 11 Mar 2009, Paul E. McKenney wrote: > Adding synchronize_rcu() into a fast path would certainly be a problem, > but call_rcu() should be OK. If the data structure is updated often > (old elements removed and new elements added), then the cache misses > from elements that were removed, went cache-cold, and then were added > again could potentially cause trouble, but read-mostly data structures > should be OK. > > Or were you worried about some other aspect of RCU overhead? > Thanks for looking at this, Paul. My latest proposal actually replaces the need for the rcu with a per-task flag called PF_SLAB_HARDWALL (see http://marc.info/?l=linux-kernel&m=123665181400366). -- 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/