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From: Yosry Ahmed To: Sergey Senozhatsky Cc: Vitaly Wool , Vlastimil Babka , hannes@cmpxchg.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Christoph Hellwig Subject: Re: [PATCH 0/3] mm: remove zpool Message-ID: References: <20250829162212.208258-1-hannes@cmpxchg.org> <20250904093325.2768507-1-vitaly.wool@konsulko.se> <7b1ca42d-1b89-44f4-bffb-e6b09f86fdc5@suse.cz> <1d42c513-cc83-4f08-a10c-cbd6206070f4@konsulko.se> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: 472C71C0007 X-Rspamd-Server: rspam05 X-Stat-Signature: caku3kiouor4czuaqye67py1byb6pxqt X-Rspam-User: X-HE-Tag: 1757448751-269303 X-HE-Meta: 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 rNpghJtV WZwUTwBKsL6mWLtN/P05wM8D3Faclog2Tw3yazHoLb9QxD/sH8tVbv24DexE2EjFfJpRtE87bdvzD8F4qaZxheQRqWl+ZwgpQTZVtWsXQTGvOFxXTup6QOHkUfJVn8ApK5f4GDYSnAXGu+yqWLOsjIM8omYLVa3fvV2uYE25/AOludg06g3I9WipYErVu4u1NbzcsWLyG3obRBoo= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Sep 08, 2025 at 09:18:01PM +0900, Sergey Senozhatsky wrote: > On (25/09/06 14:25), Sergey Senozhatsky wrote: > > On (25/09/05 19:57), Yosry Ahmed wrote: > > > I think Android uses zram+zsmalloc with 16K pages. Perhaps Sergey could > > > confirm. > > > > I'm not working on android directly, > > > > I can confirm that android uses zram+zsmalloc. As of 16K pages, there > > was a way to toggle 16k pages on android (via system settings), I don't > > know if this is the default now. > > While I don't know what zsmalloc struggles Vitaly is referring to in > particular, off the top of my head, zsmalloc does memcpy()'s for objects > that span multiple pages, when zsmalloc kmap()'s both physical pages and > memcpy()'s chunks of the object into a provided buffer. With 16K pages > we can have rather larger compressed objects, so those memcpy() are likely > more visible. Attacking this would be a good idea, I guess. Yeah I personally think attacking whatever problems zsmalloc has with 16K pages is the way to go.