Re: [Xen-users] vcpu performance : 1 vcpu for all guets or 4 vpcu ?

[Timo Benk <timo.benk@xxxxxx>]

Pascal wrote:
> Tell I have a Xeon server with 4 vcpus
> 
> If on this box I have some guets, tell 10, what is the best solutions :
> - Set all guests to 1 vcpu ?
> - Set all guests to 4 vcpus ?

In my understanding, if you set all guests to 1 vcpu, each guest can
utilize one (p)cpu at most, but most likely the credit-scheduler will
put each guest on a separate (p)cpu, thus all guests are able to run at
the same time.

If you set all guest to 4 vcpus, each guest can utilize all four (p)cpus
at most, but all guests will share these (p)cpus.

Which solution is best depends on the workload, and imho there is
no "best way" for all situations.

If all guests are at 100 percent cpu, but the guests are not able to
utilize all four vcpus because there is only one process consuming most
of the cpu time, you won't gain any profit of using four vcpus and it
may be better to use only on vcpu.

Greetings,
-timo

-- 
Timo Benk - Jabber ID: timo@xxxxxxxxx - ICQ ID: #488595326
PGP Public Key: http://www.m28s01.vlinux.de/timo_benk_gpg_key.asc


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