diff options
author | Shaohua Li <shaohua.li@intel.com> | 2011-01-16 21:52:07 -0500 |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2011-02-14 07:03:08 -0500 |
commit | 70e4a369733a21e3d16b059a6ccdad22a344bf57 (patch) | |
tree | bb103a7ea3199320dc0b7e5fdf69fe594b863e05 /arch/x86/mm/tlb.c | |
parent | 3a09fb4570a1cce11472b8e5da3f6ee409f529d5 (diff) |
x86: Scale up the number of TLB invalidate vectors with NR_CPUs, up to 32
Make the maxium TLB invalidate vectors depend on NR_CPUS linearly,
with a maximum of 32 vectors.
We currently only have 8 vectors for TLB invalidation and that is clearly
inadequate. If we have a lot of CPUs, the CPUs need share the 8 vectors and
tlbstate_lock is used to protect them. flush_tlb_page() is
heavily used in page reclaim, which will cause a lot of lock
contention for tlbstate_lock.
Andi Kleen suggested increasing the vectors number to 32, which should be
good for current typical systems to reduce the tlbstate_lock contention.
My test system has 4 sockets and 64G memory, and 64 CPUs. My
workload creates 64 processes. Each process mmap reads a big
empty sparse file. The total size of the files are 2*total_mem,
so this will cause a lot of page reclaim.
Below is the result I get from perf call-graph profiling:
without the patch:
------------------
24.25% usemem [kernel] [k] _raw_spin_lock
|
--- _raw_spin_lock
|
|--42.15%-- native_flush_tlb_others
with the patch:
------------------
14.96% usemem [kernel] [k] _raw_spin_lock
|
--- _raw_spin_lock
|--13.89%-- native_flush_tlb_others
So this heavily reduces the tlbstate_lock contention.
Suggested-by: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1295232727.1949.709.camel@sli10-conroe>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/mm/tlb.c')
0 files changed, 0 insertions, 0 deletions