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 84FE8223710; Wed, 27 Aug 2025 17:11:50 +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=1756314712; cv=none; b=R3c1VcOozZSrac/FQHLtjyiJAcZ57m0KcuHhIqcI01+yjam3fM2esPeIdpwhuqoMt5je38O3nnR4Vp8sk1njVRk4mlUqA9GrJe7zQLq6C8hw5s7q6uIBTXVuX3fAlqQHW76mLwgiXdFX11QiIJDDI3O1f4eClmN9wJWkcKoaXv4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756314712; c=relaxed/simple; bh=3aUjH47u8cHdPsl1BdlKxTzAA50pWkY6dUI3rJzJI2M=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=EftWHftbpJSOq0fzZVSQE1wNY9310WmufV8yvzfdlfbP9AWFb9lldjhzMTFgx2Dhlqw1hOaL0tmtRHomZocZQhh+fVnD6aLI22MzXZryaKpyD7JAlL9SDBdod8X2rhGZLymHwZgiw7jtuUJQH0fGz+5PQXqGUmXZSId2TpjuwkU= 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 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 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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