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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 877C8C43458 for ; Tue, 7 Jul 2026 08:36:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=mBkwwnHGuzcY60618y6u0CNrluVSVkNQLCREmDyHKaA=; b=oiHsD0CHyaz+PNdz/pqdpaAABD jFr6dIAYvoP0xJ5CLGJPs14M+q9b18rHyOKBtCa8bNtGYXX5B/7ybN8+cLEXNI0GHYK+JbMZweTqE qTaEq9AQKnUA2zS2uT3W5gspMlCfC9R+CEPVa619Vh+df+eLW12WR0DIR38lfjj5x0A3Z2x2D8/WJ w7dbVmOeDnmOYBkQcka6cTndb4Z36q5ZzAw9XBoRdexufK21mx1AIdjg1MCjRv1A093RbBKOBZCN1 DHBF0Xzbg0o/QjUjSGvVgye6DU7GW4C8LsjgZzibfbmG2EOjHaqYLIIV53da/foNj2cOklO5lXCad w6kq9e+w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wh1Hd-0000000EUiO-2OkH; Tue, 07 Jul 2026 08:36:01 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wh1HX-0000000EUhW-2KuU for linux-arm-kernel@lists.infradead.org; Tue, 07 Jul 2026 08:36:00 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id DDBCF2379; Tue, 7 Jul 2026 01:35:48 -0700 (PDT) Received: from [10.2.212.8] (e134344.arm.com [10.2.212.8]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 37E5E3F85F; Tue, 7 Jul 2026 01:35:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1783413353; bh=u3RlVTowKqTUJwgRzp3SA9YrCrbi3lk5EF2OOQEph4A=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=RQ6Y0C2Wptt8NGN3y917WJAMNoPF9+mkViw0HKaM+pw37cU5w3GN2wq/zSyBfkaPQ douyxLGmNgkVyeJzYO7uti42uJmucdVttqpysAYMQ9G+LnV4dh7WrDzO9Bbla8RDM6 pN19sG4XRgGtc5XGE2xYWPrh/LDVrceOe3vBzEcs= Message-ID: Date: Tue, 7 Jul 2026 09:35:49 +0100 MIME-Version: 1.0 User-Agent: Thunderbird Daily Subject: Re: [PATCH v4 2/3] arm_mpam: resctrl: Add pass-through resctrl_arch_preconvert_bw() To: Reinette Chatre Cc: james.morse@arm.com, fenghuay@nvidia.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, corbet@lwn.net, x86@kernel.org, linux-doc@vger.kernel.org, dave.martin@arm.com References: <20260706160639.2136674-1-ben.horgan@arm.com> <20260706160639.2136674-3-ben.horgan@arm.com> <4c520a28-9a72-4abd-8e5b-654a312c92fd@intel.com> Content-Language: en-US From: Ben Horgan In-Reply-To: <4c520a28-9a72-4abd-8e5b-654a312c92fd@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260707_013556_368676_EFFC0B3F X-CRM114-Status: GOOD ( 10.65 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Reinette, On 7/6/26 22:33, Reinette Chatre wrote: > Hi Ben, > > On 7/6/26 9:06 AM, Ben Horgan wrote: >> resctrl rounds up the percentage value of the MBA based on the bw_gran. As >> MPAM uses a binary fixed point fraction format for MBA rather than a >> decimal percentage, this introduces rounding errors. >> >> Without this additional rounding, if the user reads the value in an MB >> schema and then writes it back to the schema, the value in hardware won't >> change. However, with this additional rounding, this guarantee is broken >> for systems with mbw_wd < 7. >> >> resctrl is introducing resctrl_arch_preconvert_bw() to allow the arch code >> to specify the conversion resctrl does to the user-provided bandwidth >> value. Add the MPAM version of resctrl_arch_preconvert_bw(). This does no >> conversion. >> >> Signed-off-by: Ben Horgan >> Reviewed-by: Reinette Chatre >> > > Unfortunately the "---" separator is missing here. Another silly mistake.. sorry about that. I've corrected locally and will send a respin in a day or two. Thanks, Ben > >> Changes since v3: >> Parameter order switch (Reinette) >> Add Reinette's R-b >> --- > Reinette