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| author | Srikar Dronamraju <srikar@linux.vnet.ibm.com> | 2021-04-15 17:39:34 +0530 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2021-04-17 10:40:51 +1000 |
| commit | c1e53367dab15e41814cff4e37df8ec4ac8fb9d7 (patch) | |
| tree | 490cad3a7a3e381380a82bed254bb9180bc92785 /arch/powerpc/include/asm/smp.h | |
| parent | 131c82b6a1d261705a6f98368e501d43d994018d (diff) | |
| download | linux-stable-c1e53367dab15e41814cff4e37df8ec4ac8fb9d7.tar.gz linux-stable-c1e53367dab15e41814cff4e37df8ec4ac8fb9d7.tar.bz2 linux-stable-c1e53367dab15e41814cff4e37df8ec4ac8fb9d7.zip | |
powerpc/smp: Cache CPU to chip lookup
On systems with large CPUs per node, even with the filtered matching of
related CPUs, there can be large number of calls to cpu_to_chip_id for
the same CPU. For example with 4096 vCPU, 1 node QEMU configuration,
with 4 threads per core, system could be see upto 1024 calls to
cpu_to_chip_id() for the same CPU. On a given system, cpu_to_chip_id()
for a given CPU would always return the same. Hence cache the result in
a lookup table for use in subsequent calls.
Since all CPUs sharing the same core will belong to the same chip, the
lookup_table has an entry for one CPU per core. chip_id_lookup_table is
not being freed and would be used on subsequent CPU online post CPU
offline.
Reported-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Tested-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210415120934.232271-4-srikar@linux.vnet.ibm.com
Diffstat (limited to 'arch/powerpc/include/asm/smp.h')
| -rw-r--r-- | arch/powerpc/include/asm/smp.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h index 47081a9e13ca..03b3d010cbab 100644 --- a/arch/powerpc/include/asm/smp.h +++ b/arch/powerpc/include/asm/smp.h @@ -31,6 +31,7 @@ extern u32 *cpu_to_phys_id; extern bool coregroup_enabled; extern int cpu_to_chip_id(int cpu); +extern int *chip_id_lookup_table; #ifdef CONFIG_SMP |