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| author | Shaohua Li <shaohua.li@intel.com> | 2011-01-17 10:52:10 +0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2011-02-14 13:03:08 +0100 |
| commit | 7064d865af804b9b841e7b9a3e9b653e40c3e5ca (patch) | |
| tree | 7f4afcd7f3d9a767fe232b5455a8550c418c2898 /arch/x86/mm/tlb.c | |
| parent | 70e4a369733a21e3d16b059a6ccdad22a344bf57 (diff) | |
| download | linux-stable-7064d865af804b9b841e7b9a3e9b653e40c3e5ca.tar.gz linux-stable-7064d865af804b9b841e7b9a3e9b653e40c3e5ca.tar.bz2 linux-stable-7064d865af804b9b841e7b9a3e9b653e40c3e5ca.zip | |
x86: Avoid tlbstate lock if not enough cpus
This one isn't related to previous patch. If online cpus are
below NUM_INVALIDATE_TLB_VECTORS, we don't need the lock. The
comments in the code declares we don't need the check, but a hot
lock still needs an atomic operation and expensive, so add the
check here.
Uses nr_cpu_ids here as suggested by Eric Dumazet.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Andi Kleen <andi@firstfloor.org>
LKML-Reference: <1295232730.1949.710.camel@sli10-conroe>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/mm/tlb.c')
| -rw-r--r-- | arch/x86/mm/tlb.c | 11 |
1 files changed, 4 insertions, 7 deletions
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index 6acc724d5d8f..55272d7c3b0b 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -179,12 +179,8 @@ static void flush_tlb_others_ipi(const struct cpumask *cpumask, sender = this_cpu_read(tlb_vector_offset); f = &flush_state[sender]; - /* - * Could avoid this lock when - * num_online_cpus() <= NUM_INVALIDATE_TLB_VECTORS, but it is - * probably not worth checking this for a cache-hot lock. - */ - raw_spin_lock(&f->tlbstate_lock); + if (nr_cpu_ids > NUM_INVALIDATE_TLB_VECTORS) + raw_spin_lock(&f->tlbstate_lock); f->flush_mm = mm; f->flush_va = va; @@ -202,7 +198,8 @@ static void flush_tlb_others_ipi(const struct cpumask *cpumask, f->flush_mm = NULL; f->flush_va = 0; - raw_spin_unlock(&f->tlbstate_lock); + if (nr_cpu_ids > NUM_INVALIDATE_TLB_VECTORS) + raw_spin_unlock(&f->tlbstate_lock); } void native_flush_tlb_others(const struct cpumask *cpumask, |