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Re: [Qemu-devel] Re: KQEMU code organization
From: |
Fabrice Bellard |
Subject: |
Re: [Qemu-devel] Re: KQEMU code organization |
Date: |
Thu, 29 May 2008 23:52:34 +0200 |
User-agent: |
Thunderbird 1.5.0.9 (X11/20070212) |
Anthony Liguori wrote:
> [...]
> FWIW, the l1_phys_map table is a current hurdle in getting performance.
> When we use proper accessors to access the virtio_ring, we end up taking
> a significant performance hit (around 20% on iperf). I have some simple
> patches that implement a page_desc cache that cache the RAM regions in a
> linear array. That helps get most of it back.
>
> I'd really like to remove the l1_phys_map entirely and replace it with a
> sorted list of regions. I think this would have an overall performance
> improvement since its much more cache friendly. One thing keeping this
> from happening is the fact that the data structure is passed up to the
> kernel for kqemu. Eliminating that dependency would be a very good thing!
If the l1_phys_map is a performance bottleneck it means that the
internals of QEMU are not properly used. In QEMU/kqemu, it is not
accessed to do I/Os : a cache is used thru tlb_table[]. I don't see why
KVM cannot use a similar system.
Fabrice.
- Re: [Qemu-devel] Re: KQEMU code organization, (continued)
- Re: [Qemu-devel] Re: KQEMU code organization, Paul Brook, 2008/05/29
- Re: [Qemu-devel] Re: KQEMU code organization, Jamie Lokier, 2008/05/29
- Re: [Qemu-devel] Re: KQEMU code organization, Anthony Liguori, 2008/05/29
- Re: [Qemu-devel] Re: KQEMU code organization, Fabrice Bellard, 2008/05/29
- Re: [Qemu-devel] Re: KQEMU code organization, Mulyadi Santosa, 2008/05/29
- Re: [Qemu-devel] Re: KQEMU code organization, Andreas Färber, 2008/05/30
- Re: [Qemu-devel] Re: KQEMU code organization, Anthony Liguori, 2008/05/29
- [Qemu-devel] Re: KQEMU code organization, Jan Kiszka, 2008/05/29
- Re: [Qemu-devel] Re: KQEMU code organization, Anthony Liguori, 2008/05/29
- Re: [Qemu-devel] Re: KQEMU code organization, Avi Kivity, 2008/05/31
- Re: [Qemu-devel] Re: KQEMU code organization,
Fabrice Bellard <=
- Re: [Qemu-devel] Re: KQEMU code organization, Avi Kivity, 2008/05/31
- [Qemu-devel] Re: KQEMU code organization, Jan Kiszka, 2008/05/29
- Re: [Qemu-devel] Re: KQEMU code organization, Anthony Liguori, 2008/05/29