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Re: [kvm-devel] [Qemu-devel] Re: [PATCH 0/4] Rework alarm timer infrastr
From: |
Jamie Lokier |
Subject: |
Re: [kvm-devel] [Qemu-devel] Re: [PATCH 0/4] Rework alarm timer infrastrucure - take2 |
Date: |
Sun, 19 Aug 2007 18:15:45 +0100 |
User-agent: |
Mutt/1.4.1i |
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.
-- Jamie
- [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, Luca Tettamanti, 2007/08/18
- [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 <=
- RE: [kvm-devel] [Qemu-devel] Re: [PATCH 0/4] Rework alarmtimer infrastrucure - take2, Dor Laor, 2007/08/19
- Re: [kvm-devel] [Qemu-devel] Re: [PATCH 0/4] Rework alarm timer infrastrucure - take2, Avi Kivity, 2007/08/19
- [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