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| author | Avi Kivity <avi@redhat.com> | 2010-05-10 13:08:26 +0300 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2010-08-01 10:47:06 +0300 |
| commit | 0719837c0832a7b305e42327caa7d330462360ea (patch) | |
| tree | 73f574529aa588d5270da0a9cf048a65e863ba93 /include/linux/kvm_host.h | |
| parent | a8eeb04a44dd6dc4c8158953d9bae48849c9a188 (diff) | |
| download | lwn-0719837c0832a7b305e42327caa7d330462360ea.tar.gz lwn-0719837c0832a7b305e42327caa7d330462360ea.zip | |
KVM: Reduce atomic operations on vcpu->requests
Usually the vcpu->requests bitmap is sparse, so a test_and_clear_bit() for
each request generates a large number of unneeded atomics if a bit is set.
Replace with a separate test/clear sequence. This is safe since there is
no clear_bit() outside the vcpu thread.
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'include/linux/kvm_host.h')
| -rw-r--r-- | include/linux/kvm_host.h | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index c8a9d628898e..e820eb579108 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -636,7 +636,12 @@ static inline bool kvm_make_check_request(int req, struct kvm_vcpu *vcpu) static inline bool kvm_check_request(int req, struct kvm_vcpu *vcpu) { - return test_and_clear_bit(req, &vcpu->requests); + if (test_bit(req, &vcpu->requests)) { + clear_bit(req, &vcpu->requests); + return true; + } else { + return false; + } } #endif |