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]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8F573C02196 for ; Fri, 7 Feb 2025 09:54:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 22C25280002; Fri, 7 Feb 2025 04:54:17 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1DCBD280001; Fri, 7 Feb 2025 04:54:17 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 056E6280002; Fri, 7 Feb 2025 04:54:16 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id D7109280001 for ; Fri, 7 Feb 2025 04:54:16 -0500 (EST) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 7236B4A7FE for ; Fri, 7 Feb 2025 09:54:16 +0000 (UTC) X-FDA: 83092688112.02.897C7A8 Received: from mail-qk1-f182.google.com (mail-qk1-f182.google.com [209.85.222.182]) by imf13.hostedemail.com (Postfix) with ESMTP id 886FA20004 for ; Fri, 7 Feb 2025 09:54:14 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=gourry.net header.s=google header.b=ClCNVsSe; spf=pass (imf13.hostedemail.com: domain of gourry@gourry.net designates 209.85.222.182 as permitted sender) smtp.mailfrom=gourry@gourry.net; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1738922054; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=ICigtFivcifkpGmnUP0PlwlMfhS9Ngy2Rm3Uut/jeRA=; b=KFH4Lf8FDaU1MbC0ncZMAaH+RKPTzTCVVH5H1kAqvKCkzC4nCiCrdc0Qi7MF36LI4kIywD 5HTcJ8L8D8FA5tRc2jO6zmtp2d1l2s3fuDsNrUvzCAB4PUX3C6DY1itAYBWwqgIM4TIrSn Pvm3KAGtCOFR1h/OVbmeC7F435bFrW0= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=gourry.net header.s=google header.b=ClCNVsSe; spf=pass (imf13.hostedemail.com: domain of gourry@gourry.net designates 209.85.222.182 as permitted sender) smtp.mailfrom=gourry@gourry.net; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1738922054; a=rsa-sha256; cv=none; b=EOYePnpojAt0MHjozyMP+QXq+S8h1XDGRkA5lI5cSCfDyOeTf+JU7c/wx+djyuOcwEX4CX 4ZchSQeSm3EPq1Tm1uXUg0pTtigSFT3hpiGsgpF0OrXYv4ECUBbbJo0ZfxPu0gybiQeOD4 a9NMQdgedDSyIQER2gVQYICLAfLeMt0= Received: by mail-qk1-f182.google.com with SMTP id af79cd13be357-7b6f7d7e128so293377885a.1 for ; Fri, 07 Feb 2025 01:54:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gourry.net; s=google; t=1738922053; x=1739526853; darn=kvack.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=ICigtFivcifkpGmnUP0PlwlMfhS9Ngy2Rm3Uut/jeRA=; b=ClCNVsSeRKVAqqH76/7EqSA9Qlnv/w2oQXgXRvF6P7v50KeALc2C2I5XiVYURDiY5n iN3zVhTmGJ3j7Ho4EdiETkx/Ivw6QkjMQooFnYbGgSDBkY/RahhaEIqoVF88rZ7+RGq5 Fc7gBQGkaLprYSbFmHGoVknz3Ykdv6ho69/R6rFky+k7j8+LFIGswngQF+LEohM3TOKj lK5p3TkAvAcxae8mVmZiDY2R68E8bW5RhehdW1bAY+1GiT2OFValFFP6SMnKYcLqiq3U c1rSV7j08dmLU2MBG+AqyTAmlhRrSoQVkBkJwfe/oO5YH8JUivfz0x6eFUGNA32qb2Oi WERw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1738922053; x=1739526853; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=ICigtFivcifkpGmnUP0PlwlMfhS9Ngy2Rm3Uut/jeRA=; b=XhFXQGDojyBFDXLrotHwhN1+NASMseWNDIOLHrcBKrKter3qzob0PHnTr1yipjBHrU XdL0byoEsn1XBBjuoFPby+dmNkaZiDcf7BzonRHSAbSDMKATvFGVHnX5497be8hlGS3v uZA5nkWFKNJ1a3IaEpdu88oIF04FJtGNpFkemGVy1asZyRskWLCkPhnzFvQVSnFpCa8I n6qE2v+Zgucm0JcnCONyInXZHbOwH4rM/3xrKuzLsHfVEPJvfhC0XB3OC1BXzl3wmf4Q 10367BmeCBVwIkTjnZ0kzUh43+G8Fd/38YKNpyO58ADhCZUqQnlL2gb/H4Cxhe7NiUjR Vgqw== X-Forwarded-Encrypted: i=1; AJvYcCXF8C5kQWOZEsoBbby+hDwIO0VL1ThOH95aJtX6FGHnZ+sieGBYuPguJlpp8EU82TXXo11YFZo7qw==@kvack.org X-Gm-Message-State: AOJu0Yy5ngCps0D0FUT6ezMGiVYhKkzbpGjg4hrSYFy0XOFkSR3Ldwhf V6ArgP0+Oe6u5urTSCYGb4ZmtPmhIegkuCqBvCCGkSclW3mKn/IqIFyXPkLwDvU= X-Gm-Gg: ASbGncvD/y5hIM5aoMhqj7U+ThvL5Eh9w8J4QDLWCUm/us/1szXcEr+IJimlt+kIIxd Q+My7P8TPtBKyae4W1Aw0HoMeSRi4UbtDEmyo2IHNjtm5h8w9vDcGmcvGfsar8MoPG2cs47xi/A A/qAYNee4C6UdUo7emL9qp3dDL0uLIWDDdfjpncy4IU8yQu2JKScG5+GZKe4CswNs+ujyWiPfiz o/ojjkLY8/MkzHO8qtl4cTecpT09sUf547jfw1pRRCtds3Oqyrs6oZK018w91xYkdG0Gydi41Md HLt+RcbANPXDgwaXrVmsCfnezzd+wGtb15IhvlBiUWCcJ0/q31ULIEidPYUIUaexyAjHZDPOjQ= = X-Google-Smtp-Source: AGHT+IE935dLEAom6CKBRb6MFRAJjtVBwRQlplz4Q1/PpNm74NViOX4mql03TqBvBXafr+TIQ/4sPw== X-Received: by 2002:a05:620a:410c:b0:7b6:d273:9b4f with SMTP id af79cd13be357-7c047eb2f81mr350229385a.11.1738922053541; Fri, 07 Feb 2025 01:54:13 -0800 (PST) Received: from gourry-fedora-PF4VCD3F (pool-173-79-56-208.washdc.fios.verizon.net. [173.79.56.208]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7c041eb7f89sm167312585a.110.2025.02.07.01.54.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 07 Feb 2025 01:54:12 -0800 (PST) Date: Fri, 7 Feb 2025 04:54:10 -0500 From: Gregory Price To: Honggyu Kim Cc: Byungchul Park , kernel_team@skhynix.com, Matthew Wilcox , Hyeonggon Yoo <42.hyeyoo@gmail.com>, lsf-pc@lists.linux-foundation.org, linux-mm@kvack.org, linux-cxl@vger.kernel.org Subject: Re: [LSF/MM/BPF TOPIC] Restricting or migrating unmovable kernel allocations from slow tier Message-ID: References: <20250207072024.GA48419@system.software.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Stat-Signature: khgx9xwypsrfhky75okx57ufuz5i6np3 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 886FA20004 X-HE-Tag: 1738922054-203768 X-HE-Meta: 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 qsTjdl0z nrDmSajqCu93SZJ276hbDb7Yebor3Gc+9OnB5rOB+M95puJnqk6U/un3NBBAQniZmPI/aNJVgaXE4YNNXUob6g4MgykOnhcCMlxtE6b+cIspOBKi4HFt6E7tEqFTU6E/wRZ3KinvFbJpnEnNJI9lX3G+B1FK6fM+oOsBjdtwO8ytNsVLXv6LQrlCwZfqpLxIy0LX3yZ2vcGQrjH028PQ4YyU98rK3PTbdr8gtYRDd1EPxddkIiw3XqHzqXXvrBBbKSAcpO4wbxbjp+BhAPeQyIq3rirFM71icobpPc1MQ+H4VwaQ7mMHd3mcGMYHhF7QAOZptrwDo7tUVbUathqP5kVTqhHpwLdp04ZJ5JLAK07K8WCx3KfX5s+ppDeytiV/vsiZB1/jgM6sYn/u2xhTwNyr44g== X-Bogosity: Ham, tests=bogofilter, spamicity=0.038263, 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 Fri, Feb 07, 2025 at 06:34:43PM +0900, Honggyu Kim wrote: > On 2/7/2025 5:57 PM, Gregory Price wrote: > > > The default kernel stack size is like 16kb. You'd need like 100,000 > > threads to eat up 1.5GB, and 2048 threads only eats like 32MB. > > > > It's not an interesting amount of memory if you have a 20TB system. > > The amount might be small, but having those data in slow tier can > make performance degradation if it is heavily accessed. > > The number of accesses isn't linearly corelated to the size of the > memory region. > Right, I started by saying: [CXL is] "generally not fit for kernel use" I have the opinion that CXL memory should be defaulted to ZONE_MOVABLE, but I understand the pressure on ZONE_NORMAL means this may not be possible for large capacities. I don't think the solution is to make kernel memory migratable and allow kernel allocations on CXL. There's a reason most kernel allocations are not swappable. > Thanks, > Honggyu