From: Vlastimil Babka <vbabka@suse.cz> To: Michal Hocko <mhocko@suse.com> Cc: linux-mm@kvack.org, Mel Gorman <mgorman@suse.de>, Andrew Morton <akpm@linux-foundation.org>, Joonsoo Kim <js1304@gmail.com>, Jia He <hejianet@gmail.com>, Taku Izumi <izumi.taku@jp.fujitsu.com>, Johannes Weiner <hannes@cmpxchg.org> Subject: Re: [PATCH 1/2] mm: fix remote numa hits statistics Date: Mon, 2 Jan 2017 16:07:05 +0100 Message-ID: <cd358060-7a68-2033-8e8a-5ab188099de7@suse.cz> (raw) In-Reply-To: <20170102144634.GB18048@dhcp22.suse.cz> On 01/02/2017 03:46 PM, Michal Hocko wrote: > On Mon 02-01-17 15:16:23, Vlastimil Babka wrote: >> On 12/21/2016 09:06 AM, Michal Hocko wrote: >>> From: Michal Hocko <mhocko@suse.com> >>> >>> Jia He has noticed that b9f00e147f27 ("mm, page_alloc: reduce branches >>> in zone_statistics") has an unintentional side effect that remote node >>> allocation requests are accounted as NUMA_MISS rathat than NUMA_HIT and >>> NUMA_OTHER if such a request doesn't use __GFP_OTHER_NODE. There are >>> many of these potentially because the flag is used very rarely while >>> we have many users of __alloc_pages_node. >>> >>> Fix this by simply ignoring __GFP_OTHER_NODE (it can be removed in a >>> follow up patch) and treat all allocations that were satisfied from the >>> preferred zone's node as NUMA_HITS because this is the same node we >>> requested the allocation from in most cases. If this is not the local >>> node then we just account it as NUMA_OTHER rather than NUMA_LOCAL. >>> >>> One downsize would be that an allocation request for a node which is >>> outside of the mempolicy nodemask would be reported as a hit which is a >>> bit weird but that was the case before b9f00e147f27 already. >>> >>> Reported-by: Jia He <hejianet@gmail.com> >>> Fixes: b9f00e147f27 ("mm, page_alloc: reduce branches in zone_statistics") >>> Signed-off-by: Michal Hocko <mhocko@suse.com> >> >> cbmc tells me that this patch is not equal to pre-commit b9f00e147f27 >> (in situation where __GFP_OTHER_NODE is not passed, as that's the only >> relevant scenario after your patch), which seems unintended. >> >> counter example: >> numa_node_id() == 1 >> preferred_zone on node 0 >> allocated from zone on node 1 >> >> pre-b9f00e147f27: >> allocated zone (node 1) increased NUMA_MISS and NUMA_LOCAL >> preferred zone (node 0) increased NUMA_FOREIGN >> >> (that looks correct to me) >> >> your patch: >> allocated zone (node 1) increased NUMA_MISS >> preferred zone (node 0) increased NUMA_FOREIGN >> >> i.e. it's missing NUMA_LOCAL on node 1, which is IMHO wrong as this was >> an allocation local to the CPU (albeit a MISS wrt the preferred node). > > I guess the following should fix that, right? Yes, it does. With that, you can add: Reviewed-by: Vlastimil Babka <vbabka@suse.cz> (which is a lie, since the computer did that ;) > --- > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 647e940e6921..ea60dc06d280 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2587,17 +2587,18 @@ int __isolate_free_page(struct page *page, unsigned int order) > static inline void zone_statistics(struct zone *preferred_zone, struct zone *z) > { > #ifdef CONFIG_NUMA > - if (z->node == preferred_zone->node) { > - enum zone_stat_item local_stat = NUMA_LOCAL; > + enum zone_stat_item local_stat = NUMA_LOCAL; > > + if (z->node != numa_node_id()) > + local_stat = NUMA_OTHER; > + > + if (z->node == preferred_zone->node) > __inc_zone_state(z, NUMA_HIT); > - if (z->node != numa_node_id()) > - local_stat = NUMA_OTHER; > - __inc_zone_state(z, local_stat); > - } else { > + else { > __inc_zone_state(z, NUMA_MISS); > __inc_zone_state(preferred_zone, NUMA_FOREIGN); > } > + __inc_zone_state(z, local_stat); > #endif > } > > -- 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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply index Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-12-12 5:59 [PATCH RFC 0/1] mm, page_alloc: fix incorrect zone_statistics data Jia He 2016-12-12 5:59 ` [PATCH RFC 1/1] " Jia He 2016-12-20 9:18 ` Michal Hocko 2016-12-20 13:10 ` Mel Gorman 2016-12-20 13:26 ` Michal Hocko 2016-12-20 14:28 ` Mel Gorman 2016-12-20 14:35 ` Michal Hocko 2016-12-20 14:49 ` Vlastimil Babka 2016-12-20 14:54 ` Mel Gorman 2016-12-21 7:57 ` Michal Hocko 2016-12-21 8:06 ` [PATCH 1/2] mm: fix remote numa hits statistics Michal Hocko 2016-12-21 8:06 ` [PATCH 2/2] mm: get rid of __GFP_OTHER_NODE Michal Hocko 2017-01-02 14:18 ` Vlastimil Babka 2016-12-29 11:46 ` [PATCH 1/2] mm: fix remote numa hits statistics Mel Gorman 2016-12-29 12:28 ` Michal Hocko 2017-01-02 14:16 ` Vlastimil Babka 2017-01-02 14:46 ` Michal Hocko 2017-01-02 15:07 ` Vlastimil Babka [this message] 2016-12-20 14:42 ` [PATCH RFC 1/1] mm, page_alloc: fix incorrect zone_statistics data Mel Gorman 2016-12-20 15:13 ` Vlastimil Babka 2016-12-21 3:01 ` hejianet 2016-12-20 12:31 ` Mel Gorman 2016-12-21 3:07 ` hejianet 2017-01-02 15:30 [PATCH 0/2] numa node stats alternative fix Michal Hocko 2017-01-02 15:30 ` [PATCH 1/2] mm: fix remote numa hits statistics Michal Hocko
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=cd358060-7a68-2033-8e8a-5ab188099de7@suse.cz \ --to=vbabka@suse.cz \ --cc=akpm@linux-foundation.org \ --cc=hannes@cmpxchg.org \ --cc=hejianet@gmail.com \ --cc=izumi.taku@jp.fujitsu.com \ --cc=js1304@gmail.com \ --cc=linux-mm@kvack.org \ --cc=mgorman@suse.de \ --cc=mhocko@suse.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
Linux-mm Archive on lore.kernel.org Archives are clonable: git clone --mirror https://lore.kernel.org/linux-mm/0 linux-mm/git/0.git # If you have public-inbox 1.1+ installed, you may # initialize and index your mirror using the following commands: public-inbox-init -V2 linux-mm linux-mm/ https://lore.kernel.org/linux-mm \ linux-mm@kvack.org public-inbox-index linux-mm Example config snippet for mirrors Newsgroup available over NNTP: nntp://nntp.lore.kernel.org/org.kvack.linux-mm AGPL code for this site: git clone https://public-inbox.org/public-inbox.git