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From: Johannes Weiner <hannes@cmpxchg.org>
To: Yongmei Xie <yongmeixie@hotmail.com>
Cc: akpm@linux-foundation.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm:vmscan: fix extra adjustment for lruvec's nonresident_age in case of reactivation
Date: Tue, 21 Sep 2021 10:48:19 -0400	[thread overview]
Message-ID: <YUnwsyE87TViMNMz@cmpxchg.org> (raw)
In-Reply-To: <TYCP286MB1108D012DA436CA72029ACA7C5DF9@TYCP286MB1108.JPNP286.PROD.OUTLOOK.COM>

On Sun, Sep 19, 2021 at 11:25:09PM +0800, Yongmei Xie wrote:
> Before commit #31d8fcac, VM didn't increase nonresident_age (AKA inactive age for
> file pages) in shrink_page_list. When putback_inactive_pages was converged with
> move_pages_to_lru, both shrink_active_list and shrink_page_list use the same
> function to handle move pages to the appropriate lru under lru lock's protection.
> 
> At those day, VM didn't increase nonresident_age for second chance promotion.
> Commit #31d8fcac fix the problem. Definitely, we should account the activation
> for second chance. But move_pages_to_lru is used in reactivation in active lru
> as well for protecting code section. So I suggest to add another variable to
> tell whether reactivation or not.

This looks incorrect to me. We *should* count reactivations/rotations
on the active list toward nonresident age.

The nonresident age tracks the number of in-memory references in order
to later calculate the (minimum) reuse distance of refaulting pages.

If a page on the active list gets reactivated due to a reference, that
reference contributes to the distance of yet-to-refault pages.


  parent reply	other threads:[~2021-09-21 14:46 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 [this message]
     [not found]   ` <TYYP286MB11150330E283CC23CB16E40CC5A29@TYYP286MB1115.JPNP286.PROD.OUTLOOK.COM>
2021-10-01 16:43     ` Johannes Weiner
     [not found]       ` <TYYP286MB1115E3D67A88FFF1BFB68996C5B19@TYYP286MB1115.JPNP286.PROD.OUTLOOK.COM>
2021-10-07 16:34         ` 回复: " Johannes Weiner

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