From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 91101FEC10C for ; Tue, 24 Mar 2026 20:28:29 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 04FD06B0005; Tue, 24 Mar 2026 16:28:29 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 017EE6B0088; Tue, 24 Mar 2026 16:28:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E7FA26B008A; Tue, 24 Mar 2026 16:28:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id DA6C46B0005 for ; Tue, 24 Mar 2026 16:28:28 -0400 (EDT) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 7B1031B7DD4 for ; Tue, 24 Mar 2026 20:28:28 +0000 (UTC) X-FDA: 84582094296.07.773BC25 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf16.hostedemail.com (Postfix) with ESMTP id 74EC5180013 for ; Tue, 24 Mar 2026 20:28:26 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=qEQ6Bvve; spf=pass (imf16.hostedemail.com: domain of yosry@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=yosry@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1774384106; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=EaoaOeUX8AqjvVbZNt08iXK3Dxhpy3xpIWd3E46BrOc=; b=vb3O0u82JFp38Z6xC7R5mN7+L049OkptlRI8goNbb/BIw9nbinlRwj/58cRIMBi6dYqLfv RIRQKsmtF2udngfdTiQovnu3JStSWAuLqUnpYv1SFqoGzhzpHZUf5OC+BBEEgHLq+gGUm0 wAfrIt5bn7kzrBLhX5q7uZqaaloQlYU= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=qEQ6Bvve; spf=pass (imf16.hostedemail.com: domain of yosry@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=yosry@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774384106; a=rsa-sha256; cv=none; b=TuhhjaP/WLCMXLts1oN3ZOdhPA1sl6WxSjJ5KNZFI/7B8DX81tWRyW3vhcbeWiIOu/HHAf qXDxoDbmDhrSnOatpaMrkPm6VXSlfm7WsIRfyWWz0YJgpEk1HsnwhCv39yxe4e85TlODP8 1jsBkDVgAasblbNjsv14QfFgr9Wx8Lw= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 4DBC34453B for ; Tue, 24 Mar 2026 20:28:25 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 159E9C2BCC6 for ; Tue, 24 Mar 2026 20:28:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774384105; bh=EaoaOeUX8AqjvVbZNt08iXK3Dxhpy3xpIWd3E46BrOc=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=qEQ6Bvve7z1gj+IXfBVW9W2pdNfFAzOP8m4dc529uvDttkYLc6j2V1KA2Yt+3TjnF gmJXLXquo/GmHQdHo+/Yml3XJL/PWoNot3APu221nm0exgxGvdfNXJaVj7zCQSF0Z9 TbOqvKHYGPh5+jYG8vsKRGT0Ujnl0j5233cL/sSJDOXxbkX1TJe/TnqDOHhPEAPlsk EEb8tUCMCgR0XIFxzFh+E17Wo0E0hH2MQTJlVUp9j4wcJgJArVBhv/MmWPcr86B81p I5OIm6DMeezSf2c1MM0E+dmS8tzzJHBzLGRAtJsOuy+HJGKSx6N+j+4T8GmrrHVdj3 PAFz+CNP8DnsA== Received: by mail-ej1-f51.google.com with SMTP id a640c23a62f3a-b97ed4ad579so671073566b.3 for ; Tue, 24 Mar 2026 13:28:25 -0700 (PDT) X-Forwarded-Encrypted: i=1; AJvYcCXDoQV1RmfpcFvJfI5PuiIE86FyjF/W8Pw2kJakVCHWKq/ZIj/uu8OCiaS3guo3v9VAMzGDZTOREA==@kvack.org X-Gm-Message-State: AOJu0YzMs+UUtNDRXl0OIpliqhA0tC6UGy0wnRO6zz9FJ54032fkzS+p sRJBw8J+79UGubcOEJzf35jE0H1foVYFlB4/VXoQe+ibn6TjCOeMO/cFP2GDDlherh71GxJbKc/ Dqm+4RZyE+KlmmSLg2MKeV1TmNOJ19yo= X-Received: by 2002:a17:907:2da1:b0:b9a:7d8b:cda8 with SMTP id a640c23a62f3a-b9a7d8bd67amr54892466b.42.1774384103812; Tue, 24 Mar 2026 13:28:23 -0700 (PDT) MIME-Version: 1.0 References: <20260322061038.156146-1-liwang@redhat.com> <20260322091851.e965d3a2f0d6af5bd985407f@linux-foundation.org> In-Reply-To: From: Yosry Ahmed Date: Tue, 24 Mar 2026 13:28:12 -0700 X-Gmail-Original-Message-ID: X-Gm-Features: AaiRm53OGDgI98_zONp3zzOg_O6qapPTbqUwmQVzXx4u18gME0Yx7R3j1RulnCA Message-ID: Subject: Re: [PATCH v4 0/7] selftests/cgroup: improve zswap tests robustness and support large page sizes To: Li Wang Cc: Andrew Morton , longman@redhat.com, yosryahmed@google.com, nphamcs@gmail.com, hannes@cmpxchg.org, mhocko@kernel.org, mkoutny@suse.com, muchun.song@linux.dev, tj@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Stat-Signature: zf6zwprbjcj11c6qr5jrrrfsupjx8xau X-Rspamd-Queue-Id: 74EC5180013 X-Rspamd-Server: rspam09 X-HE-Tag: 1774384106-160518 X-HE-Meta: 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 g+zwzoqz HEy1Z14isI5sQF8T9vnaDIxU8xldFidGAlwQ035oXcuUDVkv1ABERhjx90irVi7XA1+VVanL0Uhs4cOX2INkyokkkK+/3I6HBNi10nYN4LjZbwwugEfgpGBNdM1VSAYf0ajU/TtzXTd4WYZSSsdtUoVF0cpPwIIgxJn36IBqYSu02E6BQEsveXtEPde6mPaQhXH6ndW8H4M7OWrkRLrqKWTSbUdHHc8BJuFreKrsO8SCXJOaJZNV5Gi/COK5qyfIwU3xOLBDve75/HkED1Vc3AgMhJtPqRBV5e2/Z Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > > Sashiko claims that 512 pages will end up consuming 11K to 15K in > > zswap with this setup, do you know what the actual number is? > > Not very sure, I guess each 64K page contains 1 byte of 'a' and 65535 byt= es > of zero. A single page like that compresses down to roughly 20=E2=80=9330= bytes > (a short literal plus a very long zero run, plus frame/header overhead). > So the estimate is roughly 512 =C3=97 25 bytes =E2=89=88 12.8 KB, which i= s where the > "11 to 15 kilobytes" ballpark comes from. > > > Especially with different compressors? If it's close to 64K, this > > might be a problem. > > Yes, good point, when I swith to use 'zstd' compressor, it doesn't work. > > > Maybe we can fill half of each page with increasing values? It should > > still be compressible but not too compressible. > > I tried, this method works on Lzo algorithm but not Zstd. > Anyway, I am still investigating. Do you mean the compressibility is still very high on zstd? I vaguely remember filling a page with repeating patterns (e.g. alphabet letters) seemed to produce a decent compression ratio, but I don't remember the specifics. I am pretty sure an LLM could figure out what values will work for different compression algorithms :)