Re: [Xen-devel] domains being migrated state message improvements

[Stefan Parvu <sparvu@xxxxxxxxxxxxxxxxxxxxxx>]

> Which manpage?

xentop man page:

AUTHORS
       Written by Judy Fischbach, David Hendricks, and Josh Triplett

REPORTING BUGS
       Report bugs to <xen-devel@xxxxxxxxxxxxx>.

COPYRIGHT
       Copyright  2005  International Business Machines  Corp
       This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.


But indeed checking again I see the man page is not even listing what
metrics xentop is reporting. Uauu ... Im mainly here talking about
xentop consumer and its documentation.


> It is.  That would be "not running and not blocked" which is a valid
> state for a VM to be in.
> 
> The comment in Xen still appears accurate:
> 
>     /*
>      * - domain is marked as blocked only if all its vcpus are blocked
>      * - domain is marked as running if any of its vcpus is running
>      */
> 
> Blocked gets set whenever a vcpu uses a SCHEDOP_block or SCHEDOP_poll
> hypercall.  The former for blocking until any event arrives, the latter
> when waiting for a specific event.  SCHEDOP_block is used by guests when
> idle.
> 
> With vcpu oversubscription, it is easy to have none of the vcpus running
> at the moments when their state are sampled.  It is also easy for a
> completely idle guest to have all vcpus blocked.
> 
> As a result, all 4 possible states of blocked/not blocked/running/not
> running are valid.
> 
> Not blocked and not running therefore means "domain is not idle, but not
> scheduled" which completely matches your description of oversubscribed
> host with busy VMs.
> 

And how '------' would translate to :) ? 

I meant we need to have a bit better documentation towards people which
are planning to use data from Xen for performance analysis, capacity
planning etc ... Digging into Xen source code would be overkill in some
cases.

Thanks for pointers and explanations. 



-- 
Stefan Parvu <sparvu@xxxxxxxxxxxxxxxxxxxxxx>




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