Red Hat Bugzilla – Bug 660584
NFS transfer is very slow when RHEL5.5 guest's nic type is RTL8139
Last modified: 2011-07-31 09:23:54 EDT
Description of problem:
When installing OS on guest which have a rtl8139 card via NFS, I found a lot of packets is retransmitted or timeout, and file transmission via NFS is very slow.
Then I changed nic type to e1000, file transfer speed is back to normal.
public net. private net with a private bridge.
Version-Release number of selected component:
# rpm -q kernel
# rpm -q kvm
Steps to Reproduce:
1. Start a VM with following command, and start a unattended_install:
qemu -name 'vm1'
-net tap,vlan=0,ifname='t0-045808-YVkj',script='qemu-ifup-vbr0',downscript='no' -m 4096 -smp 2,cores=1,threads=1,sockets=2
-cpu qemu64,+sse2 -soundhw ac97
-initrd '/usr/local/staf/test/RHEV/kvm-new/autotest/client/tests/kvm/initrd.img' -vnc :0 -spice port=8000,disable-ticketing -qxl 1 -rtc-td-hack -M rhel5.5.0
-append 'ks=cdrom console=ttyS0,115200 console=tty0' -no-kvm-pit-reinjection
2. tcpdump on the tap device guest created.
3. installation is slow, and many retransmission.
file transmission speed is slow, packet retransmission.
nearly no packet retransmission, file transmission speed is normal.
dmesg on guest os is attached.
*** Bug 660582 has been marked as a duplicate of this bug. ***
*** Bug 660583 has been marked as a duplicate of this bug. ***
Created attachment 465185 [details]
dmesg output on guest os