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authorSrikar Dronamraju <srikar@linux.vnet.ibm.com>2021-04-15 17:39:34 +0530
committerMichael Ellerman <mpe@ellerman.id.au>2021-04-17 10:40:51 +1000
commitc1e53367dab15e41814cff4e37df8ec4ac8fb9d7 (patch)
tree490cad3a7a3e381380a82bed254bb9180bc92785 /drivers/irqchip/irq-tb10x.c
parent131c82b6a1d261705a6f98368e501d43d994018d (diff)
downloadlinux-c1e53367dab15e41814cff4e37df8ec4ac8fb9d7.tar.bz2
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 'drivers/irqchip/irq-tb10x.c')
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