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 6CA48CA0EFF for ; Wed, 27 Aug 2025 19:18:25 +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=V1juetUG9L2DfwKUfeLO13Y43g3gKpV1NTJQYnbTr2c=; b=gkXBaMtNpd4eeACcTjn7s7tiv/ xL/z+7bOCBFhthlOZXWNd8cuqrZC0lMIfEWFKSFZXyJS9VHUn946Oza4ylwEcLjSoM+AgtRViTyIr hbupVC07i0xLjCQ0s6xLk7b6xX3X6pj9LUxs5cZTRIiqX+Us/nhOvKEBPL4zAcvibdGl8chTRFhlZ 4mpzIJSon3H+MnV30ZsDaydKGsBwpgvUBZxDuGTo/Lw8MY9gjbjbH1gwZR+3R1ZVOos8Dme2WJrwa 0CASXcSLr5wE0FFxh4YaY0jBkwXTZLZ4f5My93CtVEXAgk90F26LN1wmffjLvLDerkIKNfQkKtKWt XJkkoKVg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1urLf1-0000000GatW-0i8y; Wed, 27 Aug 2025 19:18:19 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1urJgc-0000000GH6W-2WNn for linux-arm-kernel@lists.infradead.org; Wed, 27 Aug 2025 17:11:51 +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 88CCE15A1; Wed, 27 Aug 2025 10:11:41 -0700 (PDT) Received: from [10.1.196.42] (eglon.cambridge.arm.com [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E4A633F694; Wed, 27 Aug 2025 10:11:44 -0700 (PDT) Message-ID: <2ac66605-ee6a-495b-a0fb-910926abd8b0@arm.com> Date: Wed, 27 Aug 2025 18:11:43 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 02/33] drivers: base: cacheinfo: Add helper to find the cache size from cpu+level To: Dave Martin Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-acpi@vger.kernel.org, devicetree@vger.kernel.org, shameerali.kolothum.thodi@huawei.com, D Scott Phillips OS , carl@os.amperecomputing.com, lcherian@marvell.com, bobo.shaobowang@huawei.com, tan.shaopeng@fujitsu.com, baolin.wang@linux.alibaba.com, Jamie Iles , Xin Hao , peternewman@google.com, dfustini@baylibre.com, amitsinght@marvell.com, David Hildenbrand , Rex Nie , Koba Ko , Shanker Donthineni , fenghuay@nvidia.com, baisheng.gao@unisoc.com, Jonathan Cameron , Rob Herring , Rohit Mathew , Rafael Wysocki , Len Brown , Lorenzo Pieralisi , Hanjun Guo , Sudeep Holla , Krzysztof Kozlowski , Conor Dooley , Catalin Marinas , Will Deacon , Greg Kroah-Hartman , Danilo Krummrich References: <20250822153048.2287-1-james.morse@arm.com> <20250822153048.2287-3-james.morse@arm.com> Content-Language: en-GB From: James Morse In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250827_101150_681488_544447C5 X-CRM114-Status: GOOD ( 20.37 ) 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 Dave, On 27/08/2025 11:46, Dave Martin wrote: > Hi, > > On Fri, Aug 22, 2025 at 03:29:43PM +0000, James Morse wrote: >> MPAM needs to know the size of a cache associated with a particular CPU. >> The DT/ACPI agnostic way of doing this is to ask cacheinfo. >> >> Add a helper to do this. >> diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h >> index 2dcbb69139e9..e12d6f2c6a57 100644 >> --- a/include/linux/cacheinfo.h >> +++ b/include/linux/cacheinfo.h >> @@ -148,6 +148,21 @@ static inline int get_cpu_cacheinfo_id(int cpu, int level) >> return ci ? ci->id : -1; >> } >> >> +/** >> + * get_cpu_cacheinfo_size() - Get the size of the cache. >> + * @cpu: The cpu that is associated with the cache. >> + * @level: The level of the cache as seen by @cpu. >> + * >> + * Callers must hold the cpuhp lock. >> + * Returns the cache-size on success, or 0 for an error. >> + */ > > Nit: Maybe use the wording > > cpuhp lock must be held. > > in the kerneldoc here, to match the other helpers it sits alongside. > > Otherwise, looks reasonable. Sure, >> +static inline unsigned int get_cpu_cacheinfo_size(int cpu, int level) >> +{ >> + struct cacheinfo *ci = get_cpu_cacheinfo_level(cpu, level); >> + >> + return ci ? ci->size : 0; >> +} >> + > > Orphaned function? > > Can fs/resctrl/rdtgroup.c:rdtgroup_cbm_to_size() be ported to use this? > If so, this wouldn't just be dead code in this series. Ah - I thought the MPAM driver was pulling this value in, but its the resctrl glue code. I was trying to reduce the number of trees this touches - its probably best to kick this into the next series that adds the resctrl code as its pretty trivial. Thanks, James