Hi, everyone! Last week, we start our plan to migrate all of our application server to the virtualization group. We use Squid as our cache system, we want to use xen as the host and use debian PV as guest. And the hardware info below: CPU : Intel(R) Xeon(R) CPU E5506 @ 2.13GHz X 2 memory: 16G and we gave every debian guest two cores. And 3.7GB memory. When we start one guest. We saw the performance not so good. top - 14:53:45 up 3 days, 2:57, 1 user, load average: 0.62, 0.64, 0.84 Tasks: 71 total, 2 running, 69 sleeping, 0 stopped, 0 zombie %Cpu0 : 1.0 us, 0.7 sy, 0.0 ni, 90.1 id, 0.0 wa, 0.0 hi, 4.8 si, 3.4 st %Cpu1 : 14.3 us, 15.0 sy, 0.0 ni, 61.2 id, 9.2 wa, 0.0 hi, 0.0 si, 0.3 st KiB Mem: 3747736 total, 3630068 used, 117668 free, 296244 buffers KiB Swap: 0 total, 0 used, 0 free, 1821520 cached root@backend4a:~# ifstat -b eth0 eth1 eth2 eth3 eth4 eth5 eth6 Kbps in Kbps out Kbps in Kbps out Kbps in Kbps out Kbps in Kbps out Kbps in Kbps out Kbps in Kbps out Kbps in Kbps out 8375.12 52575.00 0.44 0.00 4.31 0.00 43416.20 7713.50 0.00 0.00 43.38 31.68 300.96 26.59 9268.63 51068.23 0.44 0.00 3.73 0.00 40364.53 8733.16 0.00 0.00 13.40 15.26 8.79 12.37 7685.08 42964.82 0.44 0.00 3.71 0.00 45665.90 7254.55 0.00 0.00 1884.36 72.96 9.17 9.19 U see the cpu use about 40% of the cpu but the traffic is just 3~5MB/s. This make me doubt does the cache system Squid is suitable for virtualization. Or the bad performance caused by our configuration ? Has anyone use squid in xen can talk about ?