linux-kernel - Re: [PATCH v2 1/2] mm/zsmalloc: change back to per-size

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Message-ID: <20240624085638.GB3130923@google.com>
Date: Mon, 24 Jun 2024 17:56:38 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: Andrew Morton <akpm@...ux-foundation.org>,
	Chengming Zhou <chengming.zhou@...ux.dev>
Cc: Minchan Kim <minchan@...nel.org>,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Yosry Ahmed <yosryahmed@...gle.com>, Nhat Pham <nphamcs@...il.com>,
	Yu Zhao <yuzhao@...gle.com>, Takero Funaki <flintglass@...il.com>,
	Chengming Zhou <zhouchengming@...edance.com>,
	Dan Carpenter <dan.carpenter@...aro.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] mm/zsmalloc: change back to per-size_class lock

On (24/06/21 15:15), Chengming Zhou wrote:
> This patch is almost the revert of the commit c0547d0b6a4b ("zsmalloc:
> consolidate zs_pool's migrate_lock and size_class's locks"), which
> changed to use a global pool->lock instead of per-size_class lock and
> pool->migrate_lock, was preparation for suppporting reclaim in zsmalloc.
> Then reclaim in zsmalloc had been dropped in favor of LRU reclaim in
> zswap.
> 
> In theory, per-size_class is more fine-grained than the pool->lock,
> since a pool can have many size_classes. As for the additional
> pool->migrate_lock, only free() and map() need to grab it to access
> stable handle to get zspage, and only in read lock mode.
> 
> Signed-off-by: Chengming Zhou <chengming.zhou@...ux.dev>

Reviewed-by: Sergey Senozhatsky <senozhatsky@...omium.org>