From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id E6A15218ABD; Thu, 28 Aug 2025 14:10:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756390234; cv=none; b=FBn69poAk6gTRC0xHAx6PoaUH9XNcBJ3M5aVnE/BaYejnl3Q0+2yBbO0o15Xd0Bay4KoaVKRTLLAc+4zcbsnqiFhDSR950kDR1nZ6AvY0zLB+Hc6HCPkf740dR8+irPDc17aiR/TslG34iZrJcV8hEjWOSJ99RaaRIOEhuaEPns= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756390234; c=relaxed/simple; bh=JbfXuzndkTW2/wKmak9wb5k4WTaXXXZK9l9RYz1eD6M=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=SBa0eAZ17zixyNm/ezzu3+QcSVp4WO5ijlpJ6T2JOGVAZK91m+lplpf8WWYRXb81ThJzzAg+Zlz0UDQiVwMK1k/GRuTQTVwHOgsMXFOuLQjgV2jX8nw89GVoxTOaeXDmtQDXAEqgzYTdq9mDSZP971L0I/5+MRiAW6y9wg//ElQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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 E6FF31688; Thu, 28 Aug 2025 07:10:23 -0700 (PDT) Received: from e133380.arm.com (e133380.arm.com [10.1.197.68]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 95A893F694; Thu, 28 Aug 2025 07:10:26 -0700 (PDT) Date: Thu, 28 Aug 2025 15:10:23 +0100 From: Dave Martin To: James Morse 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 Subject: Re: [PATCH 02/33] drivers: base: cacheinfo: Add helper to find the cache size from cpu+level Message-ID: References: <20250822153048.2287-1-james.morse@arm.com> <20250822153048.2287-3-james.morse@arm.com> <2ac66605-ee6a-495b-a0fb-910926abd8b0@arm.com> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2ac66605-ee6a-495b-a0fb-910926abd8b0@arm.com> Hi James, On Wed, Aug 27, 2025 at 06:11:43PM +0100, James Morse wrote: > 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 Sure, that also works. Cheers ---Dave