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 C21EEC43458 for ; Thu, 9 Jul 2026 10:15:31 +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=hF1OuSvsIS+NC39otbFE0b920oBAHgX+1bUMiTukbmE=; b=ySlBkSEZC2WjrC3GGaG1tG4OaD bpGs7umvShoWbA6rWdI52tPn4j+bqkqyx50mzp/LEEt4jEsvUweqNi04PBqfqTtWx7P4QRtNxGdOH 9VTvsEfKMf8njRP4xzavhx4HmO8cAKdv3Y4hPHRp2crTLgJUL3PUHIPRY+8KKUnjfcWsFuhJZcM6Q kxyYamuiMaTx1XzTz5Q8bRLta+QsKl+1X1KZVDLk/cOilDULQOOBAA2pO6B4v+x/AmI42ePI9Jkjt FbHZfmzUocm5uJHiC0LRb4r0iIXw6nt/pg+jurJGFowXtcjdSkLLsZQso9K+fwz89u7f8h8mXnRiw V9XLezcQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1whl17-00000001lBa-1JdV; Thu, 09 Jul 2026 09:26:01 +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 1whl15-00000001lB7-0hFF for linux-arm-kernel@lists.infradead.org; Thu, 09 Jul 2026 09:26:00 +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 E42F9357B; Thu, 9 Jul 2026 02:25:53 -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 57F2A3F66F; Thu, 9 Jul 2026 02:25:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1783589158; bh=r1QShwB/9V/I0bdqwOV4mWuyphrL3DCBdCUyGIHA03s=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=soghxfurEEX84ljf4uRd93H+Thd3S0QZKTyNgrf/Ga7kG0mU7NGwTqf5c5fm7BGmg ssRgcMOUX3GkElbF48HVNBWA7lbZD2IhMGp/DpGGXtU+Uq57HwQr8MPEgUzoiNJLu7 fDDtZKikUufCT/CUuIZD8Kr9mEAwoj3rR4YNMHKM= Message-ID: <0aa3bbbc-c0f0-404c-b03b-9113a1e91ce5@arm.com> Date: Thu, 9 Jul 2026 10:25:54 +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> <8d5d9c98-54df-44fe-8795-189554ea2399@intel.com> Content-Language: en-US From: Ben Horgan In-Reply-To: <8d5d9c98-54df-44fe-8795-189554ea2399@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-20260709_022559_259429_F3539EE9 X-CRM114-Status: GOOD ( 16.43 ) 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 7/7/26 15:51, Reinette Chatre wrote: > Hi Ben, > > On 7/7/26 1:35 AM, Ben Horgan wrote: >> 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. > No problem. > > When you respin, could you please add a snippet to the cover about expectations > how this series should be merged? This will be the first piece of work that > touches the x86 and Arm driver as well as resctrl fs code. So far I assumed it > will go in via tip but I think it will help to state this from Arm side. Yes, I was assuming that too. I'll make it explicit in the cover letter. > We still need a plan for if/when the Arm side touches the same code though. Thankfully > this work is small. I'm open to whatever works best for you and the others involved. Thanks, Ben > > Reinette