From: "Gautham R. Shenoy" <e...@linux.vnet.ibm.com> Hi,
Currently the cacheinfo code on powerpc indexes the "cache" objects (modelling the L1/L2/L3 caches) where the key is device-tree node corresponding to that cache. On some of the POWER server platforms thread-groups within the core share different sets of caches (Eg: On SMT8 POWER9 systems, threads 0,2,4,6 of a core share L1 cache and threads 1,3,5,7 of the same core share another L1 cache). On such platforms, there is a single device-tree node corresponding to that cache and the cache-configuration within the threads of the core is indicated via "ibm,thread-groups" device-tree property. Since the current code is not aware of the "ibm,thread-groups" property, on the aforementoined systems, cacheinfo code still treats all the threads in the core to be sharing the cache because of the single device-tree node (In the earlier example, the cacheinfo code would says CPUs 0-7 share L1 cache). In this patch series, we make the powerpc cacheinfo code aware of the "ibm,thread-groups" property. We indexe the "cache" objects by the key-pair (device-tree node, thread-group id). For any CPUX, for a given level of cache, the thread-group id is defined to be the first CPU in the "ibm,thread-groups" cache-group containing CPUX. For levels of cache which are not represented in "ibm,thread-groups" property, the thread-group id is -1. We can now remove the helper function get_shared_cpu_map() and index_dir_to_cpu() since the cache->shared_cpu_map contains the correct satate of the thread-siblings sharing the cache. This has been tested on a SMT8 POWER9 system where L1 cache is split between groups of threads in the core and on an SMT8 POWER10 system where L1 and L2 caches are split between groups of threads in a core. With this patch series, on POWER10 SMT8 system, we see the following reported via sysfs: $ grep . /sys/devices/system/cpu/cpu[89]/cache/index[0123]/shared_cpu_list /sys/devices/system/cpu/cpu8/cache/index0/shared_cpu_list:8,10,12,14 /sys/devices/system/cpu/cpu8/cache/index1/shared_cpu_list:8,10,12,14 /sys/devices/system/cpu/cpu8/cache/index2/shared_cpu_list:8,10,12,14 /sys/devices/system/cpu/cpu8/cache/index3/shared_cpu_list:8-15 /sys/devices/system/cpu/cpu9/cache/index0/shared_cpu_list:9,11,13,15 /sys/devices/system/cpu/cpu9/cache/index1/shared_cpu_list:9,11,13,15 /sys/devices/system/cpu/cpu9/cache/index2/shared_cpu_list:9,11,13,15 /sys/devices/system/cpu/cpu9/cache/index3/shared_cpu_list:8-15 $ ppc64_cpu --smt=4 $ grep . /sys/devices/system/cpu/cpu[89]/cache/index[0123]/shared_cpu_list /sys/devices/system/cpu/cpu8/cache/index0/shared_cpu_list:8,10 /sys/devices/system/cpu/cpu8/cache/index1/shared_cpu_list:8,10 /sys/devices/system/cpu/cpu8/cache/index2/shared_cpu_list:8,10 /sys/devices/system/cpu/cpu8/cache/index3/shared_cpu_list:8-11 /sys/devices/system/cpu/cpu9/cache/index0/shared_cpu_list:9,11 /sys/devices/system/cpu/cpu9/cache/index1/shared_cpu_list:9,11 /sys/devices/system/cpu/cpu9/cache/index2/shared_cpu_list:9,11 /sys/devices/system/cpu/cpu9/cache/index3/shared_cpu_list:8-11 $ ppc64_cpu --smt=2 $ grep . /sys/devices/system/cpu/cpu[89]/cache/index[0123]/shared_cpu_list /sys/devices/system/cpu/cpu8/cache/index0/shared_cpu_list:8 /sys/devices/system/cpu/cpu8/cache/index1/shared_cpu_list:8 /sys/devices/system/cpu/cpu8/cache/index2/shared_cpu_list:8 /sys/devices/system/cpu/cpu8/cache/index3/shared_cpu_list:8-9 /sys/devices/system/cpu/cpu9/cache/index0/shared_cpu_list:9 /sys/devices/system/cpu/cpu9/cache/index1/shared_cpu_list:9 /sys/devices/system/cpu/cpu9/cache/index2/shared_cpu_list:9 /sys/devices/system/cpu/cpu9/cache/index3/shared_cpu_list:8-9 $ ppc64_cpu --smt=1 $ grep . /sys/devices/system/cpu/cpu[89]/cache/index[0123]/shared_cpu_list /sys/devices/system/cpu/cpu8/cache/index0/shared_cpu_list:8 /sys/devices/system/cpu/cpu8/cache/index1/shared_cpu_list:8 /sys/devices/system/cpu/cpu8/cache/index2/shared_cpu_list:8 /sys/devices/system/cpu/cpu8/cache/index3/shared_cpu_list:8 Gautham R. Shenoy (2): powerpc/cacheinfo: Lookup cache by dt node and thread-group id powerpc/cacheinfo: Remove the redundant get_shared_cpu_map() arch/powerpc/include/asm/smp.h | 3 + arch/powerpc/kernel/cacheinfo.c | 121 ++++++++++++++++++++-------------------- 2 files changed, 62 insertions(+), 62 deletions(-) -- 1.9.4
