linux-kernel - Re: [PATCH 2/5] zsmalloc: Consolidate zs_pool's migrate_lock and size

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Message-ID: <Y1vrTI3G4xitvFEr@cmpxchg.org>
Date:   Fri, 28 Oct 2022 10:46:36 -0400
From:   Johannes Weiner <hannes@...xchg.org>
To:     Nhat Pham <nphamcs@...il.com>
Cc:     akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, minchan@...nel.org,
        ngupta@...are.org, senozhatsky@...omium.org, sjenning@...hat.com,
        ddstreet@...e.org, vitaly.wool@...sulko.com
Subject: Re: [PATCH 2/5] zsmalloc: Consolidate zs_pool's migrate_lock and
 size_class's locks

On Wed, Oct 26, 2022 at 01:06:10PM -0700, Nhat Pham wrote:
> Currently, zsmalloc has a hierarchy of locks, which includes a
> pool-level migrate_lock, and a lock for each size class. We have to
> obtain both locks in the hotpath in most cases anyway, except for
> zs_malloc. This exception will no longer exist when we introduce a LRU
> into the zs_pool for the new writeback functionality - we will need to
> obtain a pool-level lock to synchronize LRU handling even in zs_malloc.
> 
> In preparation for zsmalloc writeback, consolidate these locks into a
> single pool-level lock, which drastically reduces the complexity of
> synchronization in zsmalloc.
> 
> Suggested-by: Johannes Weiner <hannes@...xchg.org>
> Signed-off-by: Nhat Pham <nphamcs@...il.com>

Acked-by: Johannes Weiner <hannes@...xchg.org>