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From: | Avi Kivity |
Subject: | Re: [Qemu-devel] Ideas wiki for GSoC 2010 |
Date: | Mon, 15 Mar 2010 17:06:57 +0200 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.8) Gecko/20100301 Fedora/3.0.3-1.fc12 Thunderbird/3.0.3 |
On 03/15/2010 03:23 PM, Anthony Liguori wrote:
On 03/15/2010 08:11 AM, Avi Kivity wrote:On 03/15/2010 03:03 PM, Joerg Roedel wrote:I will add another project - iommu emulation. Could be very useful for doing device assignment to nested guests, which could make testing a lot easier.Our experiments show that nested device assignment is pretty much required for I/O performance in nested scenarios.Really? I did a small test with virtio-blk in a nested guest (disk read with dd, so not a real benchmark) and got a reasonable read-performance of around 25MB/s from the disk in the l2-guest.Your guest wasn't doing a zillion VMREADs and VMWRITEs every exit.I plan to reduce VMREAD/VMWRITE overhead for kvm, but not much we can do for other guests.VMREAD/VMWRITEs are generally optimized by hypervisors as they tend to be costly. KVM is a bit unusual in terms of how many times the instructions are executed per exit.
Do you know offhand of any unnecessary read/writes? There's update_cr8_intercept(), but on normal exits, I don't see what else we can remove.
-- error compiling committee.c: too many arguments to function
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