Actually it doesn't refer to ping intervals, got the same effect with any delay. The issue is about slowing the network performance down on both DomU and Dom0 when doing *anything* with Dom0. I think the problem is newer started processes has a higher PRI value, which is immediate priority (PRI). You can see it by doing "ps ax --format uname,pid,cmd,pri". PRI often gets a boost (i.e. lower value) when a process is being restarted after blocking on I/O, and conversely is lowered (higher value) if it uses up its scheduler-assigned time slot without blocking, at least with the standard scheduler. Many systems have alternative schedulers with different behaviors, but in all cases PRI is the actual current priority that the scheduler has assigned; this value is influenced by, but not defined by, the assigned "niceness".
2011/4/25 George Shuklin <[email protected]> > Good day. > > Found strange behavior with xapi and guest network traffic. If we starts > to ping domU with high speed (about 3-4 pings per second) and do some > operations with xapi (f.e. xe vm-list, etc) we can see delays in pings > (up to 80 ms compare to usual 0.3-0.8). All guest are PVs. > > I dig pretty much about this and found: > > 1) raising nice number for xenstored (nice 10, nice 20) make delays > lower. > 2) Pinning dom0 and adding VCPU to dom0 slightly helps, but not > significantly. > 3) switching to bridge instead ovs makes things worse (but not really > much). > 4) CPU load in domU does not change behavior (not better, not worse) > 5) High network and disk activity for domU make it replays sometimes > longer (up to 100ms with average load < 0.5) > > In some tests I was able to get ping about 5-6ms instead 0.3-0.8 just by > running python (without options). > > I feel I miss something or do not understand. > > --- > wBR, George. > > > > _______________________________________________ > xen-api mailing list > [email protected] > http://lists.xensource.com/mailman/listinfo/xen-api > -- С уважением, Калинин Илья.
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