On 09/24/2012 06:52 PM, Avi Kivity wrote:
> On 09/24/2012 12:19 PM, Xiao Guangrong wrote:
>> On 09/24/2012 05:48 PM, Avi Kivity wrote:
>>> On 09/24/2012 07:55 AM, Xiao Guangrong wrote:
>>>> On 07/10/2012 01:05 AM, Avi Kivity wrote:
>>>>> Currently, any time a request bit is set (not too uncommon) we check all of them.
>>>>> This patchset optimizes the process slightly by skipping over unset bits using
>>>>> for_each_set_bit().
>>>>>
>>>>
>>>> I also notice that kvm_check_request costs lots of cpu time. What is the status
>>>> of this patchset?
>>>>
>>>
>>> I had problems getting rid of KVM_REQ_PENDING_TIMER. I'll try again.
>>>
>>> In what workloads did you see kvm_check_request()?
>>>
>>
>> Run kernbench on guest, and use perf to sample, this function is really
>> hot.
>>
>
> I don't see it at all. Westmere, 4-way guest.
>
This is the result i got on my laptop:
# ./perf report | grep "\[kvm\]"
85.59% qemu-kvm [kvm] [k] arch_local_irq_enable
0.18% qemu-kvm [kvm] [k] kvm_arch_vcpu_ioctl_run
0.10% qemu-kvm [kvm] [k] paging64_walk_addr_generic
0.10% qemu-kvm [kvm] [k] x86_decode_insn
0.08% qemu-kvm [kvm] [k] kvm_check_request
0.06% qemu-kvm [kvm] [k] apic_clear_vector
My box: i5-2540M CPU @ 2.60GHz * 4 + 4G
guest: 2 vcpu + 1G
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
