On 01/20/2011 09:34 AM, Minoru Usui wrote:
Hi, everyone
In an environment with multiple host machines, I want to select a suitable host automatically on which I run a VM depending on machine's load.
Libvirt has APIs to get host machine's information, but I think these APIs aren't enough for above purpose. So I suggest below changes. What do you think?
* virNodeGetInfo() This API can get "CPU frequency"(mhz member of virNodeInfo) from "cpu MHz" of /proc/cpuinfo. This value isn't constant, because it may be decrease by power saving feature.(cf. cpuspeed on RHEL)
This value is very useful for getting *present* cpu frequency, but I want to get Maximum CPU frequency, too. I want to add max_mhz member in struct virNodeInfo from /sys/device/system/cpu/cpuXX/cpufreq/cpuinfo_max_freq.
* virNodeGetFreeMemory() This API returns amount of free memory of the host machine's all node, but this value doesn't include host's cache/buffer memory. For above purpose, it would be more suitable to account cache/buffer as free memory, because most of cache/buffer memory are reclaimable. But I think virNodeGetFreeMemory()'s ABI should not change easily.
I want to add function virNodeGetCacheBufferMemory(). It returns amount of cache + buffer memory from /proc/meminfo.
* virSysinfoRead() This API is completely internal. But DMI type1 information(dmidecode -t1) is useful for above purpose, because it's one of the information which suppose to processing capacity about host machine.
I want to export virSysinfoRead() to user.
Hello, this is a great news. I was wondering if libvirt has anything like load balancing(or HA). I'm not sure if this is aim of yours resp. of this RF(C|D). Anyway, wouldn't it be better to count in total load, io-waits, idle etc. instead of just CPU freq? I agree with memory as being key element, still I would choose by more just than these two. I mean, machine can have "low" CPU utilization, perhaps even "a lot" of free RAM, yet high io-waits. I wouldn't want to migrate anything there. It might be as well as gibberish/rubbish from my side, or plain misunderstanding. I beg for forgiveness! :) Regards, Zdenek -- Zdenek Styblik Net/Linux admin OS TurnovFree.net email: stybla@turnovfree.net jabber: stybla@jabber.turnovfree.net