----- Original Message -----
From: "Chuan Liao (Jason Liao, HPservers-Core-OE-PSC)" <chuan.liao@hp.com> To: "vdsm-devel" <vdsm-devel@lists.fedorahosted.org>, engine-devel@ovirt.org Cc: "Chegu Vinod" <chegu_vinod@hp.com>, "Shang-Chun Liang (David Liang, HPservers-Core-OE-PSC)" <shangchun.liang@hp.com> Sent: Wednesday, March 12, 2014 4:09:59 AM Subject: Re: [Engine-devel] Consider iowait add into usage CPU percentage
Hi All,
Any feedback for this topic?
Add Doron and Martin in the mail list.
Best Regards, Jason Liao
From: vdsm-devel-bounces@lists.fedorahosted.org [mailto:vdsm-devel-bounces@lists.fedorahosted.org] On Behalf Of Liao, Chuan (Jason Liao, HPservers-Core-OE-PSC) Sent: 2014 年 3 月 11 日 14:02 To: vdsm-devel; engine-devel@ovirt.org Cc: Liang, Shang-Chun (David Liang, HPservers-Core-OE-PSC); Vinod, Chegu; Gilad Chaplik Subject: [vdsm] Consider iowait add into usage CPU percentage
Hi All,
On engine core, The usage CPU percentage is calculated by %sys + %usr
class VdsBrokerObjectsBuilder
function updateVDSStatisticsData
vds.setCpuSys(AssignDoubleValue(xmlRpcStruct, VdsProperties.cpu_sys));
vds.setCpuUser(AssignDoubleValue(xmlRpcStruct, VdsProperties.cpu_user));
if (vds.getCpuSys() != null && vds.getCpuUser() != null) {
vds.setUsageCpuPercent((int) (vds.getCpuSys() + vds.getCpuUser()));
}
On vdsm, The %sys, %usr and %idle is calculated like below workflow,
class API
function getStats
decStats = self._cif._hostStats.get()
class clientIF
function __init__
self._hostStats = sampling.HostStatsThread(log=log)
self._hostStats.start()
class HostStatsThread
function get
hs0, hs1 = self._samples[0], self._samples[-1]
…
jiffies = (hs1.totcpu.user - hs0.totcpu.user) % (2 ** 32)
stats['cpuUser'] = jiffies / interval / self._ncpus
jiffies = (hs1.totcpu.sys - hs0.totcpu.sys) % (2 ** 32)
stats['cpuSys'] = jiffies / interval / self._ncpus
stats['cpuIdle'] = max(0.0, 100.0 - stats['cpuUser'] - stats['cpuSys'])
class HostSample
function __init__
self.totcpu = TotalCpuSample()
class TotalCpuSample
function __init__
self.user, userNice, self.sys, self.idle = \
map(int, file('/proc/stat').readline().split()[1:5])
self.user += userNice
Question1: Why stats[‘cpuIdle’] do not use the sampling data totcpu.idle for calculating?
I have a vague memory of this calculation which tries to level the numbers. ie- the assumption is that user and sys adds up to something which is less than 100. If this is not the case (multiple core / SMT) idle will be set to 0. But possibly Dan remembers something else?
Question2: There is another data named iowait in /proc/stat, do we need to consider add this into usage CPU percentage for calculating?
Since the above excludes iowait, I wouldn't add it here. Otherwise we may have inconsistency with the numbers.
Best Regards, Jason Liao
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