From: Michal Hocko <mhocko@kernel.org>
To: Kemi Wang <kemi.wang@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
Mel Gorman <mgorman@techsingularity.net>,
Johannes Weiner <hannes@cmpxchg.org>,
Christopher Lameter <cl@linux.com>,
YASUAKI ISHIMATSU <yasu.isimatu@gmail.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Nikolay Borisov <nborisov@suse.com>,
Pavel Tatashin <pasha.tatashin@oracle.com>,
David Rientjes <rientjes@google.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Dave <dave.hansen@linux.intel.com>,
Andi Kleen <andi.kleen@intel.com>,
Tim Chen <tim.c.chen@intel.com>,
Jesper Dangaard Brouer <brouer@redhat.com>,
Ying Huang <ying.huang@intel.com>, Aaron Lu <aaron.lu@intel.com>,
Aubrey Li <aubrey.li@intel.com>, Linux MM <linux-mm@kvack.org>,
Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 3/5] mm: enlarge NUMA counters threshold size
Date: Tue, 19 Dec 2017 13:40:45 +0100 [thread overview]
Message-ID: <20171219124045.GO2787@dhcp22.suse.cz> (raw)
In-Reply-To: <1513665566-4465-4-git-send-email-kemi.wang@intel.com>
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
next prev parent reply other threads:[~2017-12-19 12:40 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-19 6:39 [PATCH v2 0/5] mm: NUMA stats code cleanup and enhancement Kemi Wang
2017-12-19 6:39 ` [PATCH v2 1/5] mm: migrate NUMA stats from per-zone to per-node Kemi Wang
2017-12-19 12:28 ` Michal Hocko
2017-12-20 5:32 ` kemi
2017-12-19 6:39 ` [PATCH v2 2/5] mm: Extends local cpu counter vm_diff_nodestat from s8 to s16 Kemi Wang
2017-12-19 12:38 ` Michal Hocko
2017-12-20 3:05 ` kemi
2017-12-19 16:05 ` Christopher Lameter
2017-12-19 16:20 ` Michal Hocko
2017-12-19 17:21 ` Christopher Lameter
2017-12-20 6:45 ` kemi
2017-12-19 6:39 ` [PATCH v2 3/5] mm: enlarge NUMA counters threshold size Kemi Wang
2017-12-19 12:40 ` Michal Hocko [this message]
2017-12-20 5:52 ` kemi
2017-12-20 10:12 ` Michal Hocko
2017-12-20 10:21 ` kemi
2017-12-21 8:06 ` kemi
2017-12-21 8:17 ` Michal Hocko
2017-12-21 8:23 ` kemi
2017-12-21 8:59 ` Michal Hocko
2017-12-21 10:31 ` kemi
2017-12-22 12:31 ` Michal Hocko
2017-12-21 17:10 ` Christopher Lameter
2017-12-22 2:06 ` kemi
2017-12-26 19:05 ` Christopher Lameter
2017-12-19 6:39 ` [PATCH v2 4/5] mm: use node_page_state_snapshot to avoid deviation Kemi Wang
2017-12-19 12:43 ` Michal Hocko
2017-12-20 6:07 ` kemi
2017-12-20 10:06 ` Michal Hocko
2017-12-20 10:24 ` kemi
2017-12-20 15:58 ` Christopher Lameter
2017-12-21 1:39 ` kemi
2017-12-19 6:39 ` [PATCH v2 5/5] mm: Rename zone_statistics() to numa_statistics() Kemi Wang
2017-12-19 12:44 ` Michal Hocko
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