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Date:   Tue, 3 Jan 2023 04:57:30 +0000
From:   Thomas =?utf-8?Q?Wei=C3=9Fschuh?= <thomas@t-8ch.de>
To:     Nhat Pham <nphamcs@gmail.com>
Cc:     akpm@linux-foundation.org, hannes@cmpxchg.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, minchan@kernel.org,
        ngupta@vflare.org, senozhatsky@chromium.org, sjenning@redhat.com,
        ddstreet@ieee.org, vitaly.wool@konsulko.com, linux@weissschuh.net
Subject: Re: [PATCH v7 0/6] Implement writeback for zsmalloc
Message-ID: <20230103045730.2ctv3n2ckzzmdzdx@snowball.t-8ch.de>
References: <20221128191616.1261026-1-nphamcs@gmail.com>
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Hi,

On Mon, Nov 28, 2022 at 11:16:09AM -0800, Nhat Pham wrote:
> Unlike other zswap's allocators such as zbud or z3fold, zsmalloc
> currently lacks the writeback mechanism. This means that when the zswap
> pool is full, it will simply reject further allocations, and the pages
> will be written directly to swap.
> 
> This series of patches implements writeback for zsmalloc. When the zswap
> pool becomes full, zsmalloc will attempt to evict all the compressed
> objects in the least-recently used zspages.

Then this part of Documentation/admin-guide/mm/zswap.rst should probably
also be updated at some point:

    However, zsmalloc does not implement compressed page eviction, so
    once zswap fills it cannot evict the oldest page, it can only reject
    new pages.

Thomas