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From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Rik van Riel <riel@redhat.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Mel Gorman <mgorman@techsingularity.net>,
	Laura Abbott <lauraa@codeaurora.org>,
	Minchan Kim <minchan@kernel.org>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Michal Nazarewicz <mina86@mina86.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Linux Memory Management List <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v5 0/6] Introduce ZONE_CMA
Date: Thu, 1 Sep 2016 15:01:43 +0900	[thread overview]
Message-ID: <20160901060142.GA25364@js1304-P5Q-DELUXE> (raw)
In-Reply-To: <87eg54rx1w.fsf@linux.vnet.ibm.com>

On Thu, Sep 01, 2016 at 11:17:23AM +0530, Aneesh Kumar K.V wrote:
> Joonsoo Kim <iamjoonsoo.kim@lge.com> writes:
> 
> > On Tue, Aug 30, 2016 at 04:09:37PM +0530, Aneesh Kumar K.V wrote:
> >> Joonsoo Kim <js1304@gmail.com> writes:
> >> 
> >> > 2016-08-29 18:27 GMT+09:00 Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>:
> >> >> js1304@gmail.com writes:
> >> >>
> >> >>> From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> >> >>>
> >> >>> Hello,
> >> >>>
> >> >>> Changes from v4
> >> >>> o Rebase on next-20160825
> >> >>> o Add general fix patch for lowmem reserve
> >> >>> o Fix lowmem reserve ratio
> >> >>> o Fix zone span optimizaion per Vlastimil
> >> >>> o Fix pageset initialization
> >> >>> o Change invocation timing on cma_init_reserved_areas()
> >> >>
> >> >> I don't see much information regarding how we interleave between
> >> >> ZONE_CMA and other zones for movable allocation. Is that explained in
> >> >> any of the patch ? The fair zone allocator got removed by
> >> >> e6cbd7f2efb433d717af72aa8510a9db6f7a7e05
> >> >
> >> > Interleaving would not work since the fair zone allocator policy is removed.
> >> > I don't think that it's a big problem because it is just matter of
> >> > timing to fill
> >> > up the memory. Eventually, memory on ZONE_CMA will be fully used in
> >> > any case.
> >> 
> >> Does that mean a CMA allocation will now be slower because in most case we
> >> will need to reclaim ? The zone list will now have ZONE_CMA in the
> >> beginning right ?
> >
> > ZONE_CMA will be used first but I don't think that CMA allocation will
> > be slower. In most case, memory would be fully used (usually
> > by page cache). So, we need reclaim or migration in any case.
> 
> Considering that the upstream kernel doesn't allow migration of THP
> pages, this would mean that migrate will fail in most case if we have
> THP enabled and the THP allocation request got satisfied via ZONE_CMA.
> Isn't that going to be a problem ?

I think that it is a separate problem. Once we restore utilization of
CMA area, it would become a problem in any case. It is just hidden by
utilization bug and should be handled separately. I guess that it's
not that hard to fix that problem.

Thanks.

  reply	other threads:[~2016-09-01  6:10 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-29  5:07 [PATCH v5 0/6] Introduce ZONE_CMA js1304
2016-08-29  5:07 ` [PATCH v5 1/6] mm/page_alloc: don't reserve ZONE_HIGHMEM for ZONE_MOVABLE request js1304
2016-09-16  3:14   ` Aneesh Kumar K.V
2016-09-22  5:30     ` Joonsoo Kim
2016-09-21  9:06   ` Vlastimil Babka
2016-08-29  5:07 ` [PATCH v5 2/6] mm/cma: introduce new zone, ZONE_CMA js1304
2016-08-30 10:35   ` Aneesh Kumar K.V
2016-08-30 12:40     ` Aneesh Kumar K.V
2016-08-31  7:58       ` Joonsoo Kim
2016-09-21  9:11   ` Vlastimil Babka
2016-08-29  5:07 ` [PATCH v5 3/6] mm/cma: populate ZONE_CMA js1304
2016-09-21  9:20   ` Vlastimil Babka
2016-09-22  5:45     ` Joonsoo Kim
2016-09-22  6:50       ` Joonsoo Kim
2016-09-22 15:59         ` Vlastimil Babka
2016-09-28  5:34           ` Joonsoo Kim
2016-08-29  5:07 ` [PATCH v5 4/6] mm/cma: remove ALLOC_CMA js1304
2016-08-29  5:07 ` [PATCH v5 5/6] mm/cma: remove MIGRATE_CMA js1304
2016-08-29  5:07 ` [PATCH v5 6/6] mm/cma: remove per zone CMA stat js1304
2016-08-29  9:27 ` [PATCH v5 0/6] Introduce ZONE_CMA Aneesh Kumar K.V
2016-08-30  8:21   ` Joonsoo Kim
2016-08-30 10:39     ` Aneesh Kumar K.V
2016-08-31  8:03       ` Joonsoo Kim
2016-09-01  5:47         ` Aneesh Kumar K.V
2016-09-01  6:01           ` Joonsoo Kim [this message]
2016-09-21 14:47           ` Aneesh Kumar K.V
2016-09-22  5:32             ` Joonsoo Kim

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