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 aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5B70ACCF9EE for ; Wed, 29 Oct 2025 09:24:16 +0000 (UTC) Received: from mx.denx.de (mx.denx.de [89.58.32.78]) by mx.groups.io with SMTP id smtpd.web11.2889.1761729852848404988 for ; Wed, 29 Oct 2025 02:24:13 -0700 Authentication-Results: mx.groups.io; dkim=pass header.i=@denx.de header.s=mx-20241105 header.b=eT4MzDqp; spf=pass (domain: denx.de, ip: 89.58.32.78, mailfrom: pavel@denx.de) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 12E37101E8B7F; Wed, 29 Oct 2025 10:24:08 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=denx.de; s=mx-20241105; t=1761729851; h=from:subject:date:message-id:to:cc:mime-version:content-type: in-reply-to:references; bh=lVCZbgtgGjI6qkEAr09WyO/TEYqUbefQ9L3sBSaPjB4=; b=eT4MzDqpcGP5T/7M47ncI5TdS6TM2sNPME3rkQuQVO3QBMh6WBLSDJoXgbWNZG+3LhFGMk +vwqxj4NXGsgZKlo+iSHTgCQQNlnjXD7MO3nXY0HLX7KrULvPLltULoG1rfE3MFMkSU/ew bnDAc+sUAH70hatACzH7w2OFSyYY2OhoVavbQmTnIGL7ywm2cEeKrXmy0H3BoewApdiA67 Xlw5CGXwbnfXgFtpz12/xUmvB2InKzDLP10eLrCRmWTlz9Mcs7PmC+crGPGAQ8PBdfr2zE FkvCooVXofGlN9D1QCBBITlMuXWOWlIe76IJS8s90W1W4ab7fv/3vyNnLLHzNw== Date: Wed, 29 Oct 2025 10:24:06 +0100 From: Pavel Machek To: Claudiu Cc: nobuhiro1.iwamatsu@toshiba.co.jp, cip-dev@lists.cip-project.org Subject: Re: [PATCH 6.12.y-cip] mm: page_alloc: Add kernel parameter to select maximum PCP batch scale number Message-ID: References: <20251027092658.84955-1-claudiu.beznea.uj@bp.renesas.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="mo7TAx6uuBYuI2Dr" Content-Disposition: inline In-Reply-To: <20251027092658.84955-1-claudiu.beznea.uj@bp.renesas.com> X-Last-TLS-Session-Version: TLSv1.3 List-Id: X-Webhook-Received: from li982-79.members.linode.com [45.33.32.79] by aws-us-west-2-korg-lkml-1.web.codeaurora.org with HTTPS for ; Wed, 29 Oct 2025 09:24:16 -0000 X-Groupsio-URL: https://lists.cip-project.org/g/cip-dev/message/20272 --mo7TAx6uuBYuI2Dr Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi! > Commit 52166607ecc9 ("mm: restrict the pcp batch scale factor to avoid > too long latency") introduced default PCP (Per-CPU Pageset) batch size as > a configuration flag. The configuration flag is CONFIG_PCP_BATCH_SCALE_MA= X. >=20 > The ARM64 defconfig has CONFIG_PCP_BATCH_SCALE_MAX=3D5. This defconfig > is used by a high range of SoCs. >=20 > The Renesas RZ/G3S SoC is a single CPU SoC, with L1$ (I-cache 32Kbytes, > D-cache 32 Kbytes), L3$ (256 Kbytes), but no L2$. It is currently used in > a configuration with 1 GiB RAM size. In this configuration, starting with > commit 52166607ecc9 ("mm: restrict the pcp batch scale factor to avoid too > long latency") the "bonnie++ -d /mnt -u root" benchmark takes ~14 minutes > while previously it took ~10 minutes. The /mnt directory is mounted on SD > card. Same behavior is reproduced on similar Renesas single core devices > (e.g., Renesas RZ/G2UL). bonnie++ version used was 1.04. >=20 > Add a new kernel parameter to allow systems like Renesas RZ/G3S to > continue have the same performance numbers with the default mainline =2E.. > This patch was posted as RFC at [1] but got no feedback. Starting with > kernel v6.17 the behaviour was restored by commits: >=20 > 18ebe55a9236 ("mm/readahead: terminate async readahead on natural boundar= y") > 38b0ece6d763 ("mm/filemap: allow arch to request folio size for exec > memory") Ok, so this is not mainline, because mainline has different solution. It is also not queued for stable. It introduces kernel parameter that will be special for -cip, not seen in mainline nor -stable. Presumably you'll be telling your customers to set the command line parameter. Would it make sense to ask them to tune the config instead? Best regards, Pavel > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -4734,6 +4734,12 @@ > for debug and development, but should not be > needed on a platform with proper driver support. > =20 > + pcp_batch_scale_max=3Dn > + Format: > + Range: 0,6 : number > + Default : CONFIG_PCP_BATCH_SCALE_MAX > + Used for setting the scale number for PCP batch scale algorithm. > + > pdcchassis=3D [PARISC,HW] Disable/Enable PDC Chassis Status codes at > boot time. > Format: { 0 | 1 } --=20 In cooperation with DENX Software Engineering GmbH, HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany --mo7TAx6uuBYuI2Dr Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EABECAB0WIQRPfPO7r0eAhk010v0w5/Bqldv68gUCaQHdNgAKCRAw5/Bqldv6 8gwBAJ9HvnmbUd6b2GgRDSRixajXu+jCzQCfaB4BItTefeMCvUP/dXJmZo2sYs0= =OzcA -----END PGP SIGNATURE----- --mo7TAx6uuBYuI2Dr--