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Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself |
Date: |
Sun, 23 May 2010 18:31:34 +0300 |
User-agent: |
Mutt/1.5.19 (2009-01-05) |
On Thu, May 20, 2010 at 02:38:16PM +0930, Rusty Russell wrote:
> On Thu, 20 May 2010 02:31:50 pm Rusty Russell wrote:
> > On Wed, 19 May 2010 05:36:42 pm Avi Kivity wrote:
> > > > Note that this is a exclusive->shared->exclusive bounce only, too.
> > > >
> > >
> > > A bounce is a bounce.
> >
> > I tried to measure this to show that you were wrong, but I was only able
> > to show that you're right. How annoying. Test code below.
>
> This time for sure!
What do you see?
On my laptop:
address@hidden testring]$ ./rusty1 share 0 1
CPU 1: share cacheline: 2820410 usec
CPU 0: share cacheline: 2823441 usec
address@hidden testring]$ ./rusty1 unshare 0 1
CPU 0: unshare cacheline: 2783014 usec
CPU 1: unshare cacheline: 2782951 usec
address@hidden testring]$ ./rusty1 lockshare 0 1
CPU 1: lockshare cacheline: 1888495 usec
CPU 0: lockshare cacheline: 1888544 usec
address@hidden testring]$ ./rusty1 lockunshare 0 1
CPU 0: lockunshare cacheline: 1889854 usec
CPU 1: lockunshare cacheline: 1889804 usec
So locked version seems to be faster than unlocked,
and share/unshare not to matter?
same on a workstation:
address@hidden ~]# ./rusty1 unshare 0 1
CPU 0: unshare cacheline: 6037002 usec
CPU 1: unshare cacheline: 6036977 usec
address@hidden ~]# ./rusty1 lockunshare 0 1
CPU 1: lockunshare cacheline: 5734362 usec
CPU 0: lockunshare cacheline: 5734389 usec
address@hidden ~]# ./rusty1 lockshare 0 1
CPU 1: lockshare cacheline: 5733537 usec
CPU 0: lockshare cacheline: 5733564 usec
using another pair of CPUs gives a more drastic
results:
address@hidden ~]# ./rusty1 lockshare 0 2
CPU 2: lockshare cacheline: 4226990 usec
CPU 0: lockshare cacheline: 4227038 usec
address@hidden ~]# ./rusty1 lockunshare 0 2
CPU 0: lockunshare cacheline: 4226707 usec
CPU 2: lockunshare cacheline: 4226662 usec
address@hidden ~]# ./rusty1 unshare 0 2
CPU 0: unshare cacheline: 14815048 usec
CPU 2: unshare cacheline: 14815006 usec
The share test seems to never finish on the
workstation. I am debugging this.
--
MST
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, (continued)
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Avi Kivity, 2010/05/06
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Rusty Russell, 2010/05/06
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Avi Kivity, 2010/05/11
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Michael S. Tsirkin, 2010/05/11
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Rusty Russell, 2010/05/19
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Avi Kivity, 2010/05/19
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Michael S. Tsirkin, 2010/05/19
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Avi Kivity, 2010/05/20
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Rusty Russell, 2010/05/20
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Rusty Russell, 2010/05/20
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself,
Michael S. Tsirkin <=
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Avi Kivity, 2010/05/23
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Michael S. Tsirkin, 2010/05/23
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Avi Kivity, 2010/05/23
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Michael S. Tsirkin, 2010/05/23
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Avi Kivity, 2010/05/24
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Michael S. Tsirkin, 2010/05/24
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Avi Kivity, 2010/05/24
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Michael S. Tsirkin, 2010/05/23
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Michael S. Tsirkin, 2010/05/23
- Re: [Qemu-devel] [PATCH RFC] virtio: put last seen used index into ring itself, Avi Kivity, 2010/05/20