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From: Yang Shi <yang.shi@linux.alibaba.com>
To: Oscar Salvador <osalvador@suse.de>,
	ying.huang@intel.com, hannes@cmpxchg.org, mhocko@suse.com,
	mgorman@techsingularity.net, kirill.shutemov@linux.intel.com,
	josef@toxicpanda.com, hughd@google.com, shakeelb@google.com,
	hdanton@sina.com, akpm@linux-foundation.org
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [v7 PATCH 1/2] mm: vmscan: remove double slab pressure by inc'ing sc->nr_scanned
Date: Tue, 11 Jun 2019 10:17:39 -0700	[thread overview]
Message-ID: <52ec93c6-a41b-e5aa-54f0-f508a5e30a09@linux.alibaba.com> (raw)
In-Reply-To: <d99fbe8f-9c80-d407-e848-0be00e3b8886@linux.alibaba.com>



On 6/11/19 10:12 AM, Yang Shi wrote:
>
>
> On 6/10/19 2:36 PM, Oscar Salvador wrote:
>> On Tue, 2019-05-28 at 14:44 +0800, Yang Shi wrote:
>>> The commit 9092c71bb724 ("mm: use sc->priority for slab shrink
>>> targets")
>>> has broken up the relationship between sc->nr_scanned and slab
>>> pressure.
>>> The sc->nr_scanned can't double slab pressure anymore.  So, it sounds
>>> no
>>> sense to still keep sc->nr_scanned inc'ed.  Actually, it would
>>> prevent
>>> from adding pressure on slab shrink since excessive sc->nr_scanned
>>> would
>>> prevent from scan->priority raise.
>> Hi Yang,
>>
>> I might be misunderstanding this, but did you mean "prevent from scan-
>> priority decreasing"?
>> I guess we are talking about balance_pgdat(), and in case
>> kswapd_shrink_node() returns true (it means we have scanned more than
>> we had to reclaim), raise_priority becomes false, and this does not let
>> sc->priority to be decreased, which has the impact that less pages will
>>   be reclaimed the next round.
>
> Yes, exactly.

BTW, for the scan priority, the smaller number the higher priority. So, 
either "raise" or "decrease" sounds correct. "raise" means the real 
priority, "decrease" means the number itself.

>
>>
>> Sorry for bugging here, I just wanted to see if I got this right.
>>
>>
>


      reply	other threads:[~2019-06-11 17:17 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-28  6:44 Yang Shi
2019-05-28  6:44 ` [v7 PATCH 2/2] mm: vmscan: correct some vmscan counters for THP swapout Yang Shi
2019-05-29  0:57   ` Huang, Ying
2019-06-10 21:36 ` [v7 PATCH 1/2] mm: vmscan: remove double slab pressure by inc'ing sc->nr_scanned Oscar Salvador
2019-06-11 17:12   ` Yang Shi
2019-06-11 17:17     ` Yang Shi [this message]

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