On 08/28/2018 11:40 AM, Will Deacon wrote: > On Fri, Aug 24, 2018 at 05:05:59PM -0600, Shuah Khan (Samsung OSG) wrote: >> Add NUMA emulation support to emulate NUMA on non-NUMA platforms. A new >> CONFIG_NUMA_EMU option enables NUMA emulation and a new kernel command >> line option "numa=fake=N" allows users to specify the configuration for >> emulation. >> >> When NUMA emulation is enabled, a flat (non-NUMA) machine will be split >> into virtual NUMA nodes when booted with "numa=fake=N", where N is the >> number of nodes, the system RAM will be split into N equal chunks and >> assigned to each node. >> >> Emulated nodes are bounded by MAX_NUMNODES and the number of memory block >> count to avoid splitting memory blocks across NUMA nodes. >> >> If NUMA emulation init fails, it will fall back to dummy NUMA init. >> >> This is tested on Raspberry Pi3b+ with ltp NUMA test suite, numactl, and >> numastat tools. In addition, tested in conjunction with cpuset cgroup to >> verify cpuset.cpus and cpuset.mems assignments. >> >> Signed-off-by: Shuah Khan (Samsung OSG) <[email protected]> >> --- >> arch/arm64/Kconfig | 9 +++ >> arch/arm64/include/asm/numa.h | 8 +++ >> arch/arm64/mm/Makefile | 1 + >> arch/arm64/mm/numa.c | 4 ++ >> arch/arm64/mm/numa_emu.c | 109 ++++++++++++++++++++++++++++++++++ >> 5 files changed, 131 insertions(+) >> create mode 100644 arch/arm64/mm/numa_emu.c > > Hmm, is this just for debugging and kernel development? If so, it's quite a > lot of code just for that. Can't you achieve the same thing by faking up the > firmware tables? > > Will >
The main intent is to use numa emulation in conjunction with cpusets for coarse memory management similar to x86_64 use-case for the same. I verified the restricted/unrestricted using cpuset cgroup to verify cpuset.cpus and cpuset.mems assignments. I could see the Restricted/Unrestricted case memory usage differences. Using this it will be possible to restrict memory usage by a class of processes or a workload or set aside memory for a workload. This adds the same feature supported by x86_64 as described in x86/x86_64/fake-numa-for-cpusets Using numa=fake and CPUSets for Resource Management I could see the Restricted/Unrestricted case memory usage differences with this patch on Raspberry Pi3b+. This can also be used to regression test higher level NUMA changes on non-NUMA as well without firmware changes. This will also provide a way to expand NUMA regression testing in kernel rings. I was able to run ltp NUMA tests on this and verify NUMA policy code on non-NUMA platform. Results below. numa01 1 TINFO: The system contains 4 nodes: numa01 1 TPASS: NUMA local node and memory affinity numa01 2 TPASS: NUMA preferred node policy numa01 3 TPASS: NUMA share memory allocated in preferred node numa01 4 TPASS: NUMA interleave policy numa01 5 TPASS: NUMA interleave policy on shared memory numa01 6 TPASS: NUMA phycpubind policy numa01 7 TPASS: NUMA local node allocation numa01 8 TPASS: NUMA MEMHOG policy numa01 9 TPASS: NUMA policy on lib NUMA_NODE_SIZE API numa01 10 TPASS: NUMA MIGRATEPAGES policy numa01 11 TCONF: hugepage is not supported grep: /sys/kernel/mm/transparent_hugepage/enabled: No such file or directory numa01 12 TCONF: THP is not supported/enabled Summary: passed 10 failed 0 skipped 2 warnings 0 thanks, -- Shuah
