Re: [PATCH 02/33] drivers: base: cacheinfo: Add helper to find the cache size from cpu+level
From: Dave Martin <Dave.Martin@arm.com>
Date: 2025-08-27 10:46:46
Also in:
linux-acpi, linux-devicetree, lkml
Hi, On Fri, Aug 22, 2025 at 03:29:43PM +0000, James Morse wrote:
quoted hunk ↗ jump to hunk
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. Signed-off-by: James Morse <james.morse@arm.com> --- Changes since v1: * Converted to kdoc. * Simplified helper to use get_cpu_cacheinfo_level(). --- include/linux/cacheinfo.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+)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.
+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. Cheers ---Dave