From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f199.google.com (mail-wr0-f199.google.com [209.85.128.199]) by kanga.kvack.org (Postfix) with ESMTP id 1E5E66B0285 for ; Tue, 19 Dec 2017 07:40:47 -0500 (EST) Received: by mail-wr0-f199.google.com with SMTP id l33so11362069wrl.5 for ; Tue, 19 Dec 2017 04:40:47 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id l38si2379982wre.522.2017.12.19.04.40.45 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 19 Dec 2017 04:40:46 -0800 (PST) Date: Tue, 19 Dec 2017 13:40:45 +0100 From: Michal Hocko Subject: Re: [PATCH v2 3/5] mm: enlarge NUMA counters threshold size Message-ID: <20171219124045.GO2787@dhcp22.suse.cz> References: <1513665566-4465-1-git-send-email-kemi.wang@intel.com> <1513665566-4465-4-git-send-email-kemi.wang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1513665566-4465-4-git-send-email-kemi.wang@intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Kemi Wang Cc: Greg Kroah-Hartman , Andrew Morton , Vlastimil Babka , Mel Gorman , Johannes Weiner , Christopher Lameter , YASUAKI ISHIMATSU , Andrey Ryabinin , Nikolay Borisov , Pavel Tatashin , David Rientjes , Sebastian Andrzej Siewior , Dave , Andi Kleen , Tim Chen , Jesper Dangaard Brouer , Ying Huang , Aaron Lu , Aubrey Li , Linux MM , Linux Kernel On Tue 19-12-17 14:39:24, Kemi Wang wrote: > We have seen significant overhead in cache bouncing caused by NUMA counters > update in multi-threaded page allocation. See 'commit 1d90ca897cb0 ("mm: > update NUMA counter threshold size")' for more details. > > This patch updates NUMA counters to a fixed size of (MAX_S16 - 2) and deals > with global counter update using different threshold size for node page > stats. Again, no numbers. To be honest I do not really like the special casing here. Why are numa counters any different from PGALLOC which is incremented for _every_ single page allocation? > --- > mm/vmstat.c | 13 +++++++++++-- > 1 file changed, 11 insertions(+), 2 deletions(-) > > diff --git a/mm/vmstat.c b/mm/vmstat.c > index 9c681cc..64e08ae 100644 > --- a/mm/vmstat.c > +++ b/mm/vmstat.c > @@ -30,6 +30,8 @@ > > #include "internal.h" > > +#define VM_NUMA_STAT_THRESHOLD (S16_MAX - 2) > + > #ifdef CONFIG_NUMA > int sysctl_vm_numa_stat = ENABLE_NUMA_STAT; > > @@ -394,7 +396,11 @@ void __inc_node_state(struct pglist_data *pgdat, enum node_stat_item item) > s16 v, t; > > v = __this_cpu_inc_return(*p); > - t = __this_cpu_read(pcp->stat_threshold); > + if (item >= NR_VM_NUMA_STAT_ITEMS) > + t = __this_cpu_read(pcp->stat_threshold); > + else > + t = VM_NUMA_STAT_THRESHOLD; > + > if (unlikely(v > t)) { > s16 overstep = t >> 1; > > @@ -549,7 +555,10 @@ static inline void mod_node_state(struct pglist_data *pgdat, > * Most of the time the thresholds are the same anyways > * for all cpus in a node. > */ > - t = this_cpu_read(pcp->stat_threshold); > + if (item >= NR_VM_NUMA_STAT_ITEMS) > + t = this_cpu_read(pcp->stat_threshold); > + else > + t = VM_NUMA_STAT_THRESHOLD; > > o = this_cpu_read(*p); > n = delta + o; > -- > 2.7.4 > -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org