From: Vlastimil Babka <vbabka@suse.cz>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Rik van Riel <riel@redhat.com>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Michal Hocko <mhocko@kernel.org>, Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 04/12] mm, page_alloc: Only check cpusets when one exists that can be mem-controlled
Date: Mon, 24 Aug 2015 22:53:37 +0200 [thread overview]
Message-ID: <55DB8451.4000102@suse.cz> (raw)
In-Reply-To: <20150824131616.GK12432@techsingularity.net>
On 24.8.2015 15:16, Mel Gorman wrote:
>>>
>>> return read_seqcount_retry(¤t->mems_allowed_seq, seq);
>>> @@ -139,7 +141,7 @@ static inline void set_mems_allowed(nodemask_t nodemask)
>>>
>>> #else /* !CONFIG_CPUSETS */
>>>
>>> -static inline bool cpusets_enabled(void) { return false; }
>>> +static inline bool cpusets_mems_enabled(void) { return false; }
>>>
>>> static inline int cpuset_init(void) { return 0; }
>>> static inline void cpuset_init_smp(void) {}
>>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>>> index 62ae28d8ae8d..2c1c3bf54d15 100644
>>> --- a/mm/page_alloc.c
>>> +++ b/mm/page_alloc.c
>>> @@ -2470,7 +2470,7 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
>>> if (IS_ENABLED(CONFIG_NUMA) && zlc_active &&
>>> !zlc_zone_worth_trying(zonelist, z, allowednodes))
>>> continue;
>>> - if (cpusets_enabled() &&
>>> + if (cpusets_mems_enabled() &&
>>> (alloc_flags & ALLOC_CPUSET) &&
>>> !cpuset_zone_allowed(zone, gfp_mask))
>>> continue;
>>
>> Here the benefits are less clear. I guess cpuset_zone_allowed() is
>> potentially costly...
>>
>> Heck, shouldn't we just start the static key on -1 (if possible), so that
>> it's enabled only when there's 2+ cpusets?
Hm wait a minute, that's what already happens:
static inline int nr_cpusets(void)
{
/* jump label reference count + the top-level cpuset */
return static_key_count(&cpusets_enabled_key) + 1;
}
I.e. if there's only the root cpuset, static key is disabled, so I think this
patch is moot after all?
> It's overkill for the amount of benefit.
>
next prev parent reply other threads:[~2015-08-24 20:53 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-24 12:09 [PATCH 00/12] Remove zonelist cache and high-order watermark checking v3 Mel Gorman
2015-08-24 12:09 ` [PATCH 01/12] mm, page_alloc: Remove unnecessary parameter from zone_watermark_ok_safe Mel Gorman
2015-08-24 12:09 ` [PATCH 02/12] mm, page_alloc: Remove unnecessary recalculations for dirty zone balancing Mel Gorman
2015-08-24 12:09 ` [PATCH 03/12] mm, page_alloc: Remove unnecessary taking of a seqlock when cpusets are disabled Mel Gorman
2015-08-26 10:25 ` Michal Hocko
2015-08-24 12:09 ` [PATCH 04/12] mm, page_alloc: Only check cpusets when one exists that can be mem-controlled Mel Gorman
2015-08-24 12:37 ` Vlastimil Babka
2015-08-24 13:16 ` Mel Gorman
2015-08-24 20:53 ` Vlastimil Babka [this message]
2015-08-25 10:33 ` Mel Gorman
2015-08-25 11:09 ` Vlastimil Babka
2015-08-26 13:41 ` Mel Gorman
2015-08-26 10:46 ` Michal Hocko
2015-08-24 12:09 ` [PATCH 05/12] mm, page_alloc: Remove unecessary recheck of nodemask Mel Gorman
2015-08-25 14:32 ` Vlastimil Babka
2015-08-24 12:09 ` [PATCH 06/12] mm, page_alloc: Use masks and shifts when converting GFP flags to migrate types Mel Gorman
2015-08-25 14:36 ` Vlastimil Babka
2015-08-24 12:09 ` [PATCH 07/12] mm, page_alloc: Distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd Mel Gorman
2015-08-24 18:29 ` Mel Gorman
2015-08-25 15:37 ` Vlastimil Babka
2015-08-26 14:45 ` Mel Gorman
2015-08-26 16:24 ` Vlastimil Babka
2015-08-26 18:10 ` Mel Gorman
2015-08-27 9:18 ` Vlastimil Babka
2015-08-25 15:48 ` Vlastimil Babka
2015-08-26 13:05 ` Michal Hocko
2015-09-08 6:49 ` Joonsoo Kim
2015-09-09 12:22 ` Mel Gorman
2015-09-18 6:25 ` Joonsoo Kim
2015-08-24 12:09 ` [PATCH 08/12] mm, page_alloc: Rename __GFP_WAIT to __GFP_RECLAIM Mel Gorman
2015-08-26 12:19 ` Vlastimil Babka
2015-08-24 12:09 ` [PATCH 09/12] mm, page_alloc: Delete the zonelist_cache Mel Gorman
2015-08-24 12:29 ` [PATCH 10/12] mm, page_alloc: Remove MIGRATE_RESERVE Mel Gorman
2015-08-24 12:29 ` [PATCH 11/12] mm, page_alloc: Reserve pageblocks for high-order atomic allocations on demand Mel Gorman
2015-08-26 12:44 ` Vlastimil Babka
2015-08-26 14:53 ` Michal Hocko
2015-08-26 15:38 ` Mel Gorman
2015-09-08 8:01 ` Joonsoo Kim
2015-09-09 12:32 ` Mel Gorman
2015-09-18 6:38 ` Joonsoo Kim
2015-09-21 10:51 ` Mel Gorman
2015-08-24 12:30 ` [PATCH 12/12] mm, page_alloc: Only enforce watermarks for order-0 allocations Mel Gorman
2015-08-26 13:42 ` Vlastimil Babka
2015-08-26 14:53 ` Mel Gorman
2015-08-28 12:10 ` Michal Hocko
2015-08-28 14:12 ` Mel Gorman
2015-09-08 8:26 ` Joonsoo Kim
2015-09-09 12:39 ` Mel Gorman
2015-09-18 6:56 ` Joonsoo Kim
2015-09-21 10:51 ` Mel Gorman
2015-09-30 8:51 ` Vitaly Wool
2015-09-30 13:52 ` Vlastimil Babka
2015-09-30 14:16 ` Vitaly Wool
2015-09-30 14:43 ` Vlastimil Babka
2015-09-30 15:18 ` Mel Gorman
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