Re: [Libvir] [PATCH] Block device and network stats (version 2)
On Tue, Aug 21, 2007 at 03:37:41AM +0100, Daniel P. Berrange wrote:
On Mon, Aug 20, 2007 at 04:31:26PM +0100, Richard W.M. Jones wrote:
> This patch adds block device and network stats. The main changes over
> the previous version are:
>
> * Remote support.
> * Change Xen network interface names to have the form
"vif<domid>.<n>"[1].
>
> Discussions about the previous version may be found starting here:
> https://www.redhat.com/archives/libvir-list/2007-August/thread.html#00064
>
> I have left use of stdint.h / int64_t, since it wasn't clear to me what
> conclusion people had arrived at.
Personally I'm for using long long, since its consistent with the other
existing APIs using 64 bit quantities. They're both standards so there's
no much of a reason to favour one over the other.
Actually I have one: we already depend on 'long long' for the libvirt
API while we don't depend yet on stdint.h / int64_t. So I really favour
using unsigned long long there.
I notice the Xen impl of the block stats only fills in the rd_req and
wr_req
fields, not the rd_bytes and wr_bytes fields. Are requests always fixed at
512 bytes in size ? If so, should be just junk those fields and only return
data in terms of the bytes (other units can be calculated as needed). As a
point of reference libstatgrab only returns bytes read/written for disks.
I really prefer to keep the rd_req and wr_req. Maybe Xen isn't smart enough
yet to provide those but other hypervisors may be smarter, and even Xen can
evolve fairly quickly. I would keep the fields and try to initialize as best
as possible depending on the hypervisor.
[...]
The interface stats look OK to me. The impl which parses
/proc/net/dev
though could be shared with the QEMU driver - only the device name needs
to be different between them - QEMU will be vnetXXX - we have the actual
dev name when we create teh TAP device, but don't bother to save it anywhere
from the looks of things.
We should probably start to create OS specific modules, I can see how
doing the same on Solaris would be different, this may help protability
a little bit, but it's not urgent IMHO.
+1 for me, once the interfaces are changed to unsigned long long,
Daniel
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