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authorAndi Kleen <ak@linux.intel.com>2016-05-23 16:24:05 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-23 17:04:14 -0700
commit725fc629ff2545b061407305ae51016c9f928fce (patch)
treed9b5ace469a064da5439bd6c96d1e714df85bab2 /kernel/kexec.c
parent5c8ccefdf46c5f87d87b694c7fbc04941c2c99a5 (diff)
downloadlinux-725fc629ff2545b061407305ae51016c9f928fce.tar.gz
kernek/fork.c: allocate idle task for a CPU always on its local node
Linux preallocates the task structs of the idle tasks for all possible CPUs. This currently means they all end up on node 0. This also implies that the cache line of MWAIT, which is around the flags field in the task struct, are all located in node 0. We see a noticeable performance improvement on Knights Landing CPUs when the cache lines used for MWAIT are located in the local nodes of the CPUs using them. I would expect this to give a (likely slight) improvement on other systems too. The patch implements placing the idle task in the node of its CPUs, by passing the right target node to copy_process() [akpm@linux-foundation.org: use NUMA_NO_NODE, not a bare -1] Link: http://lkml.kernel.org/r/1463492694-15833-1-git-send-email-andi@firstfloor.org Signed-off-by: Andi Kleen <ak@linux.intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/kexec.c')
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