IO：
1. Virtual disk I/O management mechanism in Xen
2. Token-based-QoS-resource-limiting-for-VBD-I-O
3. dm-ioband
4. ionice
for blkpid in $( pgrep blkback ); do
# 2nd lowest (6) prio in best-effort class (2)
ionice -c 2 -n 6 -p $blkpid
done
CPU：
#!/bin/sh
# cpucap
# reschedule all running xen domUs to a medium-low cpu allocation
# scheduler notes:
# if you wanna change this to support qos classes (i.e. if the customer can
# chose a certain performance level, then look at the SEDF and credit2
# schedulers, or just play around with the weight.
# I recommend using the weight for now.
# also I think a 2-core cap + very heavy weight for dom0 should be looked
# at when you see any io scalability issues.
# hyperthreading notes:
#we might see hyperthreads so we'll assume 2 cores have a
#performance of 130 => and 1 core has 65!
#this means we'll have to tweak xen vcpu allocation to ensure noone ever
#runs on a HT only?
# potential solution for figuring out
# the best solution is using a extended cpu mask (url?) in the cpus= line
# of the xen config. that, coupled with picking specific core types
# (url: http://dag.wieers.com/blog/is-hyper-threading-enabled-on-a-linux-system), would work, but is extremely complex.
#
# I will focus on giving the users multiples of 1core+1ht and stick by the
# 130 sum then...
get_vms()
{
xm list | egrep -v 'Name|Domain-0' | awk '{print $1" "$2" "$4}'
}
set_perf()
{
xm sched-credit -d domain-id -w weight =c cap
}
# xen4.1 / sched-credit2 testers needed:
# the below command is disabled for safety reasons, can crash dom0
# i bet theres still no regression test for that.
# our first try, later we should give dom0 256 * cores * total_domUs
#
# or just pin it, if we got lotsa fast cores
default_weight=256
dom0_cores=$(grep -c ^proc /proc/cpuinfo)
dom0_weight=$(( $default_weight * $dom0_cores ))
#xm sched-credit2 -d 0 weight $dom0_weight
#we should employ capping for dom0 too, feel free to move to the main code.
#xm sched-credit2 -d 0 -c 400
echo "$(get_vms)" | while read name domid vcpus ; do
xm sched-credit -d $domid -c $(( $vcpus * 65 ))
done