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On 01/14/2013 12:38 AM, jason wrote:
Hi Steven,
I have done some investigations about the heavy cpu usage of
cpgbench. I think cpu is used up mainly because if cpgbench
calls cpg_mcast_joined() with CS_ERR_TRY_AGAIN returned, it
simply try it again. Many useless trying again will happen if
the network can be easily congested. So are there any
asynchronous method we can use in that senario to reduce cpu
usage?
No such method currently exists. We have identified this spinning
as a performance issue in clients, but don't have a clear solution
to address the issue.
One thing that might be worth investigating is a callback which
identifies when flow control state changes. Currently we just mark
a bit "on or off". I have briefly discussed this some time ago with
Angus (libqb maintainer, where the ipc code is) but we didn't come
to conclusion if this would a) fix the problem b) be possible.
Regards
-steve
On Jan 9, 2013 11:10 PM, "Steven Dake"
<sdake@xxxxxxxxxx>
wrote:
On 01/08/2013 11:26 PM, jason wrote:
Update : By using iperf to check multicast performance,
iperf also give a bad result(100Mbit/sec) on my virtual
machine, but CPU usage is very low(only 1%). The command
I used is :
iperf -c 239.255.1.10 -u -l 8K -b 1G -w -i 5 -t 300 -T 4
Jason,
Unfortunately the virtual network drivers perform very
poorly with multicast. Multicast is not a operational mode
the authors of those operating system drivers have
optimized. You might try udpu which uses unicast (which has
been optimized), although I can't guarantee performance will
be great either.
Most of the development of Corosync is on bare metal and
optimized for that environment.
Totem uses alot of CPU to operate, especially with
encryption. The usage may be higher depending on how many
cpu cores you have and which version you are using. 1.4.x
uses threads, which cause some context switching chaos - so
more cores here would be helpful. I'd recommend giving 2.x
a try if you haven't.
Between our two virtual machines, iperf -i 1 -w 1M
can reach line rate that is 1.00 Gbit/sec. But I do
not know why cpgbench only got 10 MB/s. And when
cpgbench was running, top showed it used up almost
one CPU. 30% in usermode, 70% for in kernel mode.
jason napsal(a):
> Hi All,
> Currently we created a 16
nodes(virtuallization) cluser environment to test
cool
> the performance of the Totem protocol. We wan
to see the relationship
> between the cluster size(the amount of nodes
) and the bandwidth/latency.
After you will finish testing, can you please
share results?
> And I found there are already some test
utilities that I can use such as
> cpgbench, evtbench and pload and I want to
know which tool is the best
> that I should use to meet my requirement and
is there any other way to test
Question is, what type of performance you would
like to test. Is that
bandwidth, or latency? Network or local one?
cpgbench seems to be
generally best for testing both bandwidth (with
big messages) and
latency (with small messages). I would not
recommend pload, because this
makes corosync to behave weird (it's almost
removed in 2.x).
