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 89266CD98C6 for ; Thu, 11 Jun 2026 04:35:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 750DE6B008C; Thu, 11 Jun 2026 00:35:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 728206B0092; Thu, 11 Jun 2026 00:35:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 665BB6B0093; Thu, 11 Jun 2026 00:35:57 -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 557806B008C for ; Thu, 11 Jun 2026 00:35:57 -0400 (EDT) Received: from smtpin30.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id BE316140471 for ; Thu, 11 Jun 2026 04:35:56 +0000 (UTC) X-FDA: 84866369112.30.6610739 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf08.hostedemail.com (Postfix) with ESMTP id 16AB7160002 for ; Thu, 11 Jun 2026 04:35:54 +0000 (UTC) Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=jKw6Or8P; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf08.hostedemail.com: domain of harry@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=harry@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1781152555; 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=RBtM2K5HAboXGskkkhCTAIlRz7iBBSjZG1WoOi7K0cE=; b=efGVXPG3QE2Oyv6qDFbPYsn4N+HvAx64b1okfCArTNpNbYbuKJGrA8YhiZIRqceryCM+M+ KmI6pFjMJASwLBTORI8CPD1oGAa8c9m/NmRBdkgN9JD5lCFtnxlV3M0RISY/AZjzXEIPt8 qi0kqBqs8nYdY07BUNTSWSkrTV8m8kc= ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=jKw6Or8P; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf08.hostedemail.com: domain of harry@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=harry@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1781152555; b=8iqhIhwBXCK3rw8bFoVDPBUxTJeWB68uGBF+Rs8CkS9j9HkQGL4QsWU9gf6fVyWO8SeQ7M Xqr1F0di1/mJeJcwhzKKFDpntYY275tnVAc7zz2vSKMb5+913pk93oivxcOSwQ5s01Xghx 5mjJy82Ats4J3ci6j6m2XxtpNLCwiuQ= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id EF49640328; Thu, 11 Jun 2026 04:35:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85FB31F00893; Thu, 11 Jun 2026 04:35:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781152553; bh=RBtM2K5HAboXGskkkhCTAIlRz7iBBSjZG1WoOi7K0cE=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=jKw6Or8PUn8mM8QSyoHKukGjtNmlEqJLvHQXxCKMjvgSAlvbSPoDtHTLOYjUPSQMX NUGcsOnXvnSQEF/D4RZYRH72AtZFetepAJKnJFaN1FEZ7g7HCyUnLnMtcm6u9tXYPQ J2txDzG1CviQKZVz4dEtzlCb2+gdfMWMpgzsAVtrBe3kSoI0sc44MW4S+ABd2tYW2b W2HW+2LV+fu86k7mBZNf0HAtKphWM17UmDjwWB7Km+tLcDq2sBDTdF+hpHZE1+55C9 B4Q2y19JfLFCQfy9+KiN88LL7a4COOlpBWE8DaGGgb8+3iCH1aCWlZyZmF671FzsPS gmIH6I0Fm7TzQ== Message-ID: Date: Thu, 11 Jun 2026 13:35:46 +0900 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/5] mm/khugepaged: use slab cache instead of normal kmalloc To: Luka Bai , "Vlastimil Babka (SUSE)" Cc: linux-mm@kvack.org, Andrew Morton , David Hildenbrand , Lorenzo Stoakes , Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kairui Song , Qi Zheng , Shakeel Butt , Axel Rasmussen , Yuanchu Xie , Wei Xu , Rik van Riel , Jann Horn , Johannes Weiner , linux-kernel@vger.kernel.org, Luka Bai References: <20260531-thp_collapse_hint-v1-0-e7f8c2035621@tencent.com> <20260531-thp_collapse_hint-v1-2-e7f8c2035621@tencent.com> Content-Language: en-US From: Harry Yoo In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="------------s0FuOZXCRkHyas8wwz3tzD0p" X-Rspamd-Queue-Id: 16AB7160002 X-Rspam-User: X-Stat-Signature: rk1fenx5xy9i8xhpskhwmyr1aot6muj1 X-Rspamd-Server: rspam09 X-HE-Tag: 1781152554-288371 X-HE-Meta: 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 BAVfYH44 a4wi7jXZEI6mqw7dAKnSDdO6u03TR8ouaMjpQpAxipV23IcWaAgzB5d3GcIKKWGqk2Ct7v8XJ9/cHGCcy0qrOk6iOxeAwNCi2khJTf2IVVW1jQ8uk7O8XMOaY1WMQf2D4se7AUcWyOp4VnhnQ0Yo0NSf01duN3CEYZdStmvGLKSOO9UsAUOIVJois382C/2GFsRMVEFe8moNpg3F6owVrV9Fjcmf1UZX3FT7+hVJSOXu8ijDqtWPik9xEAMrGD8rPXDdO4co5wg0jIzP3CSvcflUSwJAOEWTfXI3xDhBv+6fWVtqYukZsG1Q3ZrGkxzkORimJug9w3xEUtF2DJ32qJKwPTeNL9g15c/OnMTVd6WhN4+cvfaJLB/Ig+Njw3Bz9Sa6yBPe0rOEVgc4GqDxlHLQDQnuXJ8skEEJJpqCxsszuhSY/8kWjszoUxrTMEdKQt5AU7vMHmJFIK28a8hNKzNg5lOLpID33xw/k Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --------------s0FuOZXCRkHyas8wwz3tzD0p Content-Type: multipart/mixed; boundary="------------JMw89MqN6K3e0LGsnFwEl6z0"; protected-headers="v1" From: Harry Yoo To: Luka Bai , "Vlastimil Babka (SUSE)" Cc: linux-mm@kvack.org, Andrew Morton , David Hildenbrand , Lorenzo Stoakes , Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kairui Song , Qi Zheng , Shakeel Butt , Axel Rasmussen , Yuanchu Xie , Wei Xu , Rik van Riel , Jann Horn , Johannes Weiner , linux-kernel@vger.kernel.org, Luka Bai Message-ID: Subject: Re: [PATCH 2/5] mm/khugepaged: use slab cache instead of normal kmalloc References: <20260531-thp_collapse_hint-v1-0-e7f8c2035621@tencent.com> <20260531-thp_collapse_hint-v1-2-e7f8c2035621@tencent.com> In-Reply-To: --------------JMw89MqN6K3e0LGsnFwEl6z0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 6/11/26 12:16 PM, Luka Bai wrote: > =E5=9C=A8 Tue, Jun 09, 2026 at 12:26:18PM +0200=EF=BC=8CVlastimil Babka= (SUSE) =E5=86=99=E9=81=93=EF=BC=9A >> On 5/31/26 06:23, Luka Bai wrote: >>> From: Luka Bai >>> >>> We added a kmem slab cached called collapse_hint_cache for >>> khugepaged collapse hint, to improve the performance in allocation >>> and freeing for the hint structs. >>> >>> Signed-off-by: Luka Bai >> >> Khugepaged isn't exactly a hotpath? Adding own cache comes with memory= >> overhead, so this doesn't seem like a sufficient reason to do that. >> > Hi Vlastimil, >=20 > Thanks for the review :). >=20 > Yeah Khugepaged is not a hotpath. But in my implementation we will allo= cate > those khugepaged collapse hint structs in other paths like walk_mm() an= d > lru_gen_look_around(), which may be called more frequently under memory= > pressure. I'm a little afraid that directly using kmalloc may compromis= e > the performance of reclaimation... What do you think? Thanks. :) What makes you think using kmalloc compromises the performance under memory pressure? > Best regards, > Luka --=20 Cheers, Harry / Hyeonggon --------------JMw89MqN6K3e0LGsnFwEl6z0-- --------------s0FuOZXCRkHyas8wwz3tzD0p Content-Type: application/pgp-signature; name="OpenPGP_signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="OpenPGP_signature.asc" -----BEGIN PGP SIGNATURE----- iHUEARYKAB0WIQQQ1ub6gR5ogjaKRmOGXBN6rc5S1gUCaio7IgAKCRCGXBN6rc5S 1iGEAQCcjg+KNn4s7QndYuB9qY/SnSuBzaTEp6GosQ8dG2oEhQD9Gf4bo4jevpE4 1qR5mrl3EDcwM1nWunUMATpFPfo4vwU= =7p8w -----END PGP SIGNATURE----- --------------s0FuOZXCRkHyas8wwz3tzD0p--