From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934868AbcJMSRJ (ORCPT ); Thu, 13 Oct 2016 14:17:09 -0400 Received: from mx2.suse.de ([195.135.220.15]:34741 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934797AbcJMSQw (ORCPT ); Thu, 13 Oct 2016 14:16:52 -0400 Date: Thu, 13 Oct 2016 19:16:37 +0100 From: Mel Gorman To: Andi Kleen Cc: Andi Kleen , peterz@infradead.org, linux-mm@kvack.org, akpm@linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Don't touch single threaded PTEs which are on the right node Message-ID: <20161013181637.GF20573@suse.de> References: <1476288949-20970-1-git-send-email-andi@firstfloor.org> <20161013083910.GC20573@suse.de> <20161013180402.GI3078@tassilo.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20161013180402.GI3078@tassilo.jf.intel.com> 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 On Thu, Oct 13, 2016 at 11:04:02AM -0700, Andi Kleen wrote: > > > do { > > > oldpte = *pte; > > > @@ -94,6 +100,13 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd, > > > /* Avoid TLB flush if possible */ > > > if (pte_protnone(oldpte)) > > > continue; > > > + > > > + /* > > > + * Don't mess with PTEs if page is already on the node > > > + * a single-threaded process is running on. > > > + */ > > > + if (target_node == page_to_nid(page)) > > > + continue; > > > } > > > > > > > Check target_node != NUMA_NODE && target_node == page_to_nid(page) to > > avoid unnecessary page->flag masking and shifts? > > I didn't do this last change because I expect a potentially mispredicted > check is more expensive than some shifting/masking. > Ok, that's fair enough. For something that minor I expect it to be a case of "you win some you lose some" depending on workload, CPU and phase of the moon. Thanks. -- Mel Gorman SUSE Labs