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From: Shakeel Butt To: Yosry Ahmed Cc: Hao Jia , Johannes Weiner , mhocko@kernel.org, tj@kernel.org, mkoutny@suse.com, roman.gushchin@linux.dev, Nhat Pham , akpm@linux-foundation.org, chengming.zhou@linux.dev, muchun.song@linux.dev, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Hao Jia Subject: Re: [PATCH v3 2/4] mm/zswap: Implement proactive writeback Message-ID: References: <20260526114601.67041-1-jiahao.kernel@gmail.com> <20260526114601.67041-3-jiahao.kernel@gmail.com> <6deeaea7-3cd1-4403-29fc-d2dc55c297f8@gmail.com> <6db27a22-cc7a-9a94-db3f-c912fd39aa32@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-HE-Tag: 1780581691-742935 X-HE-Meta: U2FsdGVkX1+SvOWubH70LFDFq7x9di3hsL1nUVlsoyI9nspKHdgPZNMnKF3xuvYjdKcgRbZeWCnND6k4YUCBnoFgrrmF4orM7fB5TrE2Kj9+GHEgp0w8doIPRiQnmk4bza7gYvo6gSww/nmEe9liUqC3GEBE2KdASNyesEd0uxjxdW2ld0TLUMPecSAEgnLU5L5YE0XFZkLopQrSMqmOzRYFB/Sd+PEk1ADuEOhxQzJwKTzvDZeNvwFSHHi0pDnGBGMm0XO8CeqJwHuAsnQ4jv0tomGoFK1QyWSwpjmTrVnthUkvS8Xt/g6lWVKpYDE5s11RWfeseFFKw10Zg8I9daWtpVwJqJ976rFRYmJv/GRtSJ9+X4hTetcvtsUIuiTd Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jun 03, 2026 at 10:36:07PM -0700, Yosry Ahmed wrote: > > >> But doesn't it make more sense to specify the compressed size, which is > > >> ultimately the amount of memory you actually want to reclaim. > > >> > > > > > > I personally prefer compressed size to pre-compressed size. That's > > > kinda what user cares about, no? > > > > > > One thing we can do is let users prescribe a compressed size, but > > > internally, we can multiply that by the average compression ratio. > > > That gives us a guesstimate of how many pages we need to reclaim, and > > > you can follow the rest of your implementation as is (perhaps with > > > short-circuit when we reach the goal with fewer pages reclaimed). > > > > Got it. I will change it to use the compressed size in the next version. > > > > Yosry, Nhat, should we continue using the zswap_writeback_only key to > > trigger proactive writeback? > > I *really* want the memcg maintainers to chime in here, it's > ultimately their call. > > Michal? Johannes? Shakeel? Roman? Anyone? :D Sorry for the delay, I will take a look in a day or two.