Per subject. "git bisect run" script (and libvirt xml helper) attached.
87b5acf6125d205119e3194c02ed6e71715517dc is first bad commit
commit 87b5acf6125d205119e3194c02ed6e71715517dc
Author: Anthony Liguori <[EMAIL PROTECTED]>
Date: Wed May 7 13:09:40 2008 -0500
kvm: qemu: stop dropping so many RX packets in tap
Normally, tap always reads packets and simply lets the client drop them if it
cannot receive them. For virtio-net, this results in massive packet loss
and
about an 80% performance loss in TCP throughput.
This patch modifies qemu_send_packet() to only deliver a packet to a VLAN
client if it doesn't have a fd_can_read method or the fd_can_read method
indicates that it can receive packets. We also return a status of whether
any clients were able to receive the packet.
If no clients were able to receive a packet, we buffer the packet until a
client indicates that it can receive packets again.
This patch also modifies the tap code to only read from the tap fd if at least
one client on the VLAN is able to receive a packet.
Finally, this patch changes the tap code to drain all possible packets from
the tap device when the tap fd is readable.
Signed-off-by: Anthony Liguori <[EMAIL PROTECTED]>
Signed-off-by: Avi Kivity <[EMAIL PROTECTED]>
:040000 040000 648a4d52612e0ce68167f279d30bd3f4ec0f22f4
85352e7b252abb1247af2f024eab10a3e8ec0084 M qemu
#!/bin/bash
LIBVIRT_VM_NAME=com.m1dev.syseng.cduffy.boottest
LIBVIRT_VM_XML=/local/src/kvm-e1000-test.xml
VM_CONSOLE_LOG=/local/src/kvm-e1000-test.out
SRC_TREE_USER=/local/src/kvm-userspace
SRC_TREE_KERN=/local/src/kvm
set -e
function try_patch() {
local PATCH="$1"
if patch -f -p0 --dry-run < "$PATCH" ; then
patch -p0 < "$PATCH"
fi
return 0
}
function cleanup() {
virsh destroy ${LIBVIRT_VM_NAME} || true
rm -f ${VM_CONSOLE_LOG}
}
function test_failure() {
exit 125
}
trap test_failure 0
cd ${SRC_TREE_USER}
git reset --hard
try_patch ../kvm-userspace.centos5_compat.kvm-69.patch
try_patch ../kvm-userspace.centos5_compat.kvm-70.patch
./configure \
--prefix=/opt/kvm.git \
--kerneldir=/usr/src/kernels/2.6.18-92.1.6.el5-x86_64 \
--disable-gfx-check \
--disable-sdl
make WANT_MODULE= KERNELDIR=${SRC_TREE_KERN} clean
make WANT_MODULE= KERNELDIR=${SRC_TREE_KERN}
make WANT_MODULE= KERNELDIR=${SRC_TREE_KERN} install
git reset --hard
cleanup
virsh create "${LIBVIRT_VM_XML}"
sleep 5
if [ ! -e "${VM_CONSOLE_LOG}" ] ; then
echo 'ERR: No virtual console detected' >&2
exit 125
fi
echo 'Waiting for kernel splash notice' >&2
trap - 0
trap cleanup 0
COUNTDOWN=60
while [ "$COUNTDOWN" -gt 0 ] ; do
echo -n '.' >&2
COUNTDOWN="$(($COUNTDOWN - 1))"
sleep 1
if grep -e 'Linux version' ${VM_CONSOLE_LOG} ; then
echo 'OK: net boot succeeded' >&2
exit 0
fi
done
echo 'BAD: no net boot detected' >&2
exit 1
<domain type='kvm'>
<name>com.m1dev.syseng.cduffy.boottest</name>
<uuid>70d09285-f451-426d-8ab0-4c4810616ce6</uuid>
<memory>768432</memory>
<currentMemory>768432</currentMemory>
<vcpu>1</vcpu>
<os>
<type arch='i686' machine='pc'>hvm</type>
<boot dev='network'/>
</os>
<features>
<acpi/>
</features>
<clock offset='utc'/>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>destroy</on_crash>
<devices>
<emulator>/opt/kvm.git/bin/qemu-system-x86_64</emulator>
<disk type='file' device='disk'>
<source file='/local/VM/com.m1dev.syseng.cduffy.boottest.raw'/>
<target dev='sda' bus='scsi'/>
</disk>
<interface type='network'>
<mac address='00:16:3e:fe:cb:31'/>
<source network='com.m1dev.syseng.cduffy'/>
<model type='e1000'/>
</interface>
<console type='file'>
<source path='/local/src/kvm-e1000-test.out'/>
<target port='0'/>
</console>
</devices>
</domain>
