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RE: [kvm-devel] [Qemu-devel] Re: [PATCH 0/4] Rework alarmtimer infrastru
From: |
Dor Laor |
Subject: |
RE: [kvm-devel] [Qemu-devel] Re: [PATCH 0/4] Rework alarmtimer infrastrucure - take2 |
Date: |
Sun, 19 Aug 2007 12:29:10 -0700 |
>Paul Brook wrote:
>> > Yes, good thinking, but this should only be done if it actually
>impacts
>> > something. Reducing overhead from 0.1% to 0.05% is not worthwhile
>if it
>> > introduces extra complexity.
>>
>> If the overhead is that small, why are we touching this code in the
>first
>> place?
>
>Insightful.
>
>A benchmark result was posted which is rather interesting:
>
>>address@hidden ~]$ time ./hackbench 50
>>x86_64 host : real 0m10.845s
>>x86_64 host, bound to 1 cpu : real 0m21.884s
>>i386 guest+unix clock : real 0m49.206s
>>i386 guest+hpet clock : real 0m48.292s
>>i386 guest+dynticks clock : real 0m28.835s
>>
>>Results are repeatable and verfied with a stopwatch because I didn't
>>believe them at first :)
>
>I am surprised if 1000 redundant SIGALRMs per second is really causing
>70% overhead in normal qemu execution, except on a rather old or slow
>machine where signal delivery is very slow.
>
>It would be good to understand the cause of that benchmark result.
while I don't know the benchmark [I head it's something like paralled
chat messaging,
the performance gain is probably achieved by improved latency and
response times that
the dyn-tick provides.
- [Qemu-devel] Re: [kvm-devel] [PATCH 0/4] Rework alarm timer infrastrucure - take2, (continued)
- [Qemu-devel] Re: [kvm-devel] [PATCH 0/4] Rework alarm timer infrastrucure - take2, Anthony Liguori, 2007/08/18
- [Qemu-devel] RE: [kvm-devel] [PATCH 0/4] Rework alarm timer infrastrucure -take2, Dor Laor, 2007/08/19
- [Qemu-devel] Re: [kvm-devel] [PATCH 0/4] Rework alarm timer infrastrucure - take2, Avi Kivity, 2007/08/19
- Re: [Qemu-devel] Re: [kvm-devel] [PATCH 0/4] Rework alarm timer infrastrucure - take2, Jamie Lokier, 2007/08/19
- Re: [kvm-devel] [Qemu-devel] Re: [PATCH 0/4] Rework alarm timer infrastrucure - take2, Avi Kivity, 2007/08/19
- Re: [kvm-devel] [Qemu-devel] Re: [PATCH 0/4] Rework alarm timer infrastrucure - take2, Paul Brook, 2007/08/19
- Re: [kvm-devel] [Qemu-devel] Re: [PATCH 0/4] Rework alarm timer infrastrucure - take2, Avi Kivity, 2007/08/19
- RE: [kvm-devel] [Qemu-devel] Re: [PATCH 0/4] Rework alarm timer infrastrucure - take2, Dor Laor, 2007/08/19
- Re: [kvm-devel] [Qemu-devel] Re: [PATCH 0/4] Rework alarm timer infrastrucure - take2, Avi Kivity, 2007/08/20
- Re: [kvm-devel] [Qemu-devel] Re: [PATCH 0/4] Rework alarm timer infrastrucure - take2, Jamie Lokier, 2007/08/19
- RE: [kvm-devel] [Qemu-devel] Re: [PATCH 0/4] Rework alarmtimer infrastrucure - take2,
Dor Laor <=
- Re: [kvm-devel] [Qemu-devel] Re: [PATCH 0/4] Rework alarm timer infrastrucure - take2, Avi Kivity, 2007/08/19
- [Qemu-devel] Re: [kvm-devel] [PATCH 0/4] Rework alarm timer infrastrucure - take2, Luca, 2007/08/19
- [Qemu-devel] Re: [kvm-devel] [PATCH 0/4] Rework alarm timer infrastrucure - take2, Avi Kivity, 2007/08/19
- [Qemu-devel] Re: [kvm-devel] [PATCH 0/4] Rework alarm timer infrastrucure - take2, Luca Tettamanti, 2007/08/20
- Re: [Qemu-devel] Re: [kvm-devel] [PATCH 0/4] Rework alarm timer infrastrucure - take2, malc, 2007/08/20
- Re: [kvm-devel] [Qemu-devel] Re: [PATCH 0/4] Rework alarm timer infrastrucure - take2, Luca, 2007/08/20
- [Qemu-devel] Re: [kvm-devel] [PATCH 0/4] Rework alarm timer infrastrucure - take2, Avi Kivity, 2007/08/21
- [Qemu-devel] Re: [kvm-devel] [PATCH 0/4] Rework alarm timer infrastrucure - take2, Luca Tettamanti, 2007/08/21
- [Qemu-devel] Re: [kvm-devel] [PATCH 0/4] Rework alarm timer infrastrucure - take2, malc, 2007/08/21
- [Qemu-devel] Re: [kvm-devel] [PATCH 0/4] Rework alarm timer infrastrucure - take2, Avi Kivity, 2007/08/22