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From: Johannes Weiner <hannes@cmpxchg.org>
To: "解 咏梅" <yongmeixie@hotmail.com>
Cc: "akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: 回复: [PATCH] mm:vmscan: fix extra adjustment for lruvec's nonresident_age in case of reactivation
Date: Fri, 1 Oct 2021 12:43:56 -0400	[thread overview]
Message-ID: <YVc6zOy51aaRgw2y@cmpxchg.org> (raw)
In-Reply-To: <TYYP286MB11150330E283CC23CB16E40CC5A29@TYYP286MB1115.JPNP286.PROD.OUTLOOK.COM>

On Wed, Sep 22, 2021 at 02:27:24PM +0000, 解 咏梅 wrote:
> But now, move_pages_to_lru didn't increase nonresident age for active rotation.
> Back toinactive age, VM ONLY care about the pages left inactive lru, AKA activation and reclaiming.
> Anyway reactivation is rare case, so whatever it contributes to nonresident age or not is ok to me.
> 
> But I am interested the logic how to guess the pages will be referenced again in the future.
> If active reactivation does matter to nonresident age. why not active rotation? But, currently it doesn't.

Can you point me to the code you're referring to? Looking at
move_pages_to_lru(), any pages with PageActive() set count toward the
non-resident age. That means activations from the inactive list, as
well as rotations on the active list, increase the nonresident age.

As to your question which one is right: the original workingset patch
was wrong not to count activations and reactivations. If we see a page
referenced in memory, it means it's hotter than the page that's not
refaulting -> nonresident age increses.

So the code as it is now looks correct to me.

Thanks


  parent reply	other threads:[~2021-10-01 16:44 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-19 15:25 [PATCH] mm:vmscan: fix extra adjustment for lruvec's nonresident_age in case of reactivation Yongmei Xie
2021-09-20  3:11 ` 回复: " 解 咏梅
2021-09-21 14:48 ` Johannes Weiner
     [not found]   ` <TYYP286MB11150330E283CC23CB16E40CC5A29@TYYP286MB1115.JPNP286.PROD.OUTLOOK.COM>
2021-10-01 16:43     ` Johannes Weiner [this message]
     [not found]       ` <TYYP286MB1115E3D67A88FFF1BFB68996C5B19@TYYP286MB1115.JPNP286.PROD.OUTLOOK.COM>
2021-10-07 16:34         ` 回复: 回复: " Johannes Weiner

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