From: Vlastimil Babka <vbabka@suse.cz>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Michal Hocko <mhocko@kernel.org>,
Mel Gorman <mgorman@techsingularity.net>,
David Rientjes <rientjes@google.com>,
Rik van Riel <riel@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 10/11] mm, compaction: require only min watermarks for non-costly orders
Date: Thu, 18 Aug 2016 14:20:10 +0200 [thread overview]
Message-ID: <7ae4baec-4eca-e70b-2a69-94bea4fb19fa@suse.cz> (raw)
In-Reply-To: <20160816064630.GH17448@js1304-P5Q-DELUXE>
On 08/16/2016 08:46 AM, Joonsoo Kim wrote:
> On Tue, Aug 16, 2016 at 08:36:12AM +0200, Vlastimil Babka wrote:
>> On 08/16/2016 08:16 AM, Joonsoo Kim wrote:
>>> On Wed, Aug 10, 2016 at 11:12:25AM +0200, Vlastimil Babka wrote:
>>>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>>>> index 621e4211ce16..a5c0f914ec00 100644
>>>> --- a/mm/page_alloc.c
>>>> +++ b/mm/page_alloc.c
>>>> @@ -2492,7 +2492,7 @@ int __isolate_free_page(struct page *page, unsigned int order)
>>>>
>>>> if (!is_migrate_isolate(mt)) {
>>>> /* Obey watermarks as if the page was being allocated */
>>>> - watermark = low_wmark_pages(zone) + (1 << order);
>>>> + watermark = min_wmark_pages(zone) + (1UL << order);
>>>
>>> This '1 << order' also needs some comment. Why can't we use
>>> compact_gap() in this case?
>>
>> This is just short-cutting the high-order watermark check to check
>> only order-0, because we already know the high-order page exists.
>> We can't use compact_gap() as that's too high to use for a single
>> allocation watermark, since we can be already holding some free
>> pages on the list. So it would defeat the gap purpose.
>
> Oops. I missed that. Thanks for clarifying it.
So let's expand the comment?
----8<----
next prev parent reply other threads:[~2016-08-18 12:20 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-10 9:12 [PATCH v6 00/11] make direct compaction more deterministic Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 01/11] mm, compaction: make whole_zone flag ignore cached scanner positions Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 02/11] mm, compaction: cleanup unused functions Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 03/11] mm, compaction: rename COMPACT_PARTIAL to COMPACT_SUCCESS Vlastimil Babka
2016-08-18 9:01 ` Michal Hocko
2016-08-10 9:12 ` [PATCH v6 04/11] mm, compaction: don't recheck watermarks after COMPACT_SUCCESS Vlastimil Babka
2016-08-16 6:12 ` Joonsoo Kim
2016-08-16 6:11 ` Vlastimil Babka
2016-08-18 11:59 ` Vlastimil Babka
2016-08-18 9:03 ` Michal Hocko
2016-08-10 9:12 ` [PATCH v6 05/11] mm, compaction: add the ultimate direct compaction priority Vlastimil Babka
2016-08-16 5:58 ` Joonsoo Kim
2016-08-18 12:23 ` Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 06/11] mm, compaction: more reliably increase " Vlastimil Babka
2016-08-16 6:07 ` Joonsoo Kim
2016-08-16 6:31 ` Vlastimil Babka
2016-08-18 9:10 ` Michal Hocko
2016-08-18 9:44 ` Vlastimil Babka
2016-08-18 9:48 ` Michal Hocko
2016-08-10 9:12 ` [PATCH v6 07/11] mm, compaction: use correct watermark when checking compaction success Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 08/11] mm, compaction: create compact_gap wrapper Vlastimil Babka
2016-08-16 6:15 ` Joonsoo Kim
2016-08-16 6:15 ` Vlastimil Babka
2016-08-16 6:41 ` Joonsoo Kim
2016-08-18 12:13 ` Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 09/11] mm, compaction: use proper alloc_flags in __compaction_suitable() Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 10/11] mm, compaction: require only min watermarks for non-costly orders Vlastimil Babka
2016-08-16 6:16 ` Joonsoo Kim
2016-08-16 6:36 ` Vlastimil Babka
2016-08-16 6:46 ` Joonsoo Kim
2016-08-18 12:20 ` Vlastimil Babka [this message]
2016-08-10 9:12 ` [PATCH v6 11/11] mm, vmscan: make compaction_ready() more accurate and readable Vlastimil Babka
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