RE: [Xen-devel] Regarding TX/RX rings

[George Shuklin <george.shuklin@xxxxxxxxx>]

Well...

I'd like to pointed to this again: HVM machine without PV network
dirvers lack of network statistics.

Ð ÐÐÑ, 23/10/2010 Ð 12:03 +1100, James Harper ÐÐÑÐÑ:
> > Hi All,
> > 
> > I have to monitor the rate of data transfer over a time window for TX/RX 
> > rings
> > in DOM0 for all DOMUs.
> > 
> > Is there a good place to start with in terms of code ? Any pointers of 
> > sample
> > implementation already existing for this will be useful.
> > 
> 
> For what purpose?
> 
> Why monitor the rings directly rather than monitoring throughput at a level 
> that already allows such things (disk io / network io etc)?
> 
> Would you be monitoring rings slots used or actual data?
> 
> There appears to be data available in /sys/devices/vbd-<domid>-<devid> that 
> might tell you what you want for vbd's (at least there is in 2.6.31.12 - your 
> kernel might be different). That may correlate directly to rings slots or may 
> be an abstraction. Vbd only has one ring containing both read and write 
> requests but the stats seem to break it down.
> 
> For network you can find throughput information in the 
> /sys/devices/vif-<domid>-<devid>/net:vif<domid>.<devid>/statistics (maybe a 
> few ways to get there) but that seems more packet oriented, and a single 
> packet doesn't correlate directly to a ring slot - you could have 1 packet 
> taking several rings slots and for GSO you could have a 'large' packet in one 
> ring slot that would be broken up into several MTU sized packets. You'd 
> probably need to implement a similar statistics reporting function in vif 
> like vbd to tell you what you want to know about the actual rings.
> 
> James
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