Installation guide

rate=10Mb/s
Limit the outgoing network traffic from the guest to 10MB/s.
rate=250KB/s
Limit the outgoing network traffic from the guest to 250KB/s.
rate=10MB/s@50ms
Limit bandwidth to 10MB/s and provide the guest with a 50KB chunk every 50ms.
In the virtual machine configuration a sample VIF entry would look like the following:
vif = [ 'rate=10MB/s , mac=00:16:3e:7a:55:1c, bridge=xenbr1']
This rate entry would limit the virtual machine's interface to 10MB/s for outgoing traffic
33.11. Configuring Xen processor affinit ies
Xen can allocate virtual CPUs to associate with one or more host CPUs. This allocates real
processing resources to guests. This approach allows Red Hat Enterprise Linux optimize processor
resources when employing dual-core, hyper-threading, or other CPU concurrency technologies. The
Xen credit scheduler automatically balances virtual CPUs between physical ones, to maximize
system use. Red Hat Enterprise Linux allows the credit scheduler to move CPUs around as
necessary, as long as the virtual CPU is pinned to a physical CPU.
If you are running I/O intensive tasks, it is recommended to dedicate either a hyperthread or an entire
processor core to run domain0.
Note that this is unnecessary for KVM as KVM uses the default Linux kernel scheduler.
CPU affinities can be set with virsh or virt-manager:
To set CPU affinities using virsh see Configuring virtual CPU affinity for more information.
To configure and view CPU information with virt-manager see Section 27.11, “ Displaying virtual
CPUs ” for more information.
33.12. Modifying t he Xen hypervisor
Managing host systems often involves changing the boot configuration file
/boot/grub/grub.conf. Managing several or more hosts configuration files quickly becomes
difficult. System administrators often prefer to use the 'cut and paste' method for editing multiple
grub.conf files. If you do this, ensure you include all five lines in the Virtualization entry (or this will
create system errors). Hypervisor specific values are all found on the 'xen' line. This example
represents a correct grub.conf virtualization entry:
# boot=/dev/sda/
default=0
timeout=15
#splashimage=(hd0, 0)/grub/splash.xpm.gz
hiddenmenu
serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1
terminal --timeout=10 serial console
title Red Hat Enterprise Linux Server (2.6.17-1.2519.4.21. el5xen)
⁠Chapt er 33. T ips and t ricks
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