[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH v2 06/22] block: Add "supports_stats" field to B
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH v2 06/22] block: Add "supports_stats" field to BlockStats |
Date: |
Wed, 21 Oct 2015 11:01:24 +0100 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
On Fri, Oct 16, 2015 at 11:49:00AM +0200, Alberto Garcia wrote:
> On Thu 15 Oct 2015 04:58:22 PM CEST, Stefan Hajnoczi wrote:
> >> > If I/O accounting isn't being used then all fields will be 0?
> >>
> >> Yes, but there's no way to tell if that happens because I/O
> >> accounting is not supported or because there hasn't been any I/O yet.
> >>
> >> There's one additional problem: this patch assumes that accounting is
> >> supported if this BDS is attached to a BlockBackend. But we don't
> >> know if the device model supports accounting or not, I still need to
> >> figure out what's the best way to do it.
> >
> > Is there a corresponding libvirt patch or why does it matter whether
> > the QMP client can detect whether blockstats are available?
>
> I'm thinking that keeping this patch as it is now is probably not very
> useful.
>
> Block statistics are kept in the BlockBackend, so the only BDS that is
> going to have data != 0 when you call query-blockstats is the topmost
> one. There's probably no need to have an additional flag for this.
>
> If you disconnect a BlockBackend from a device model that implements
> accounting and then connect it to one that does not, there's no way for
> the client to know that. That's probably worth exposing in the API, but
> this patch does not do that yet, so I think we can skip it for now.
Okay.
Stefan
- [Qemu-devel] [PATCH v2 04/22] util: Infrastructure for computing recent averages, (continued)
[Qemu-devel] [PATCH v2 07/22] block: Add statistics for failed and invalid I/O operations, Alberto Garcia, 2015/10/08
[Qemu-devel] [PATCH v2 03/22] block: define 'clock_type' for the accounting code, Alberto Garcia, 2015/10/08
[Qemu-devel] [PATCH v2 09/22] block: Compute minimum, maximum and average I/O latencies, Alberto Garcia, 2015/10/08
[Qemu-devel] [PATCH v2 11/22] block: New option to define the intervals for collecting I/O statistics, Alberto Garcia, 2015/10/08
[Qemu-devel] [PATCH v2 02/22] ide: Account for write operations correctly, Alberto Garcia, 2015/10/08
[Qemu-devel] [PATCH v2 21/22] scsi-disk: Account for failed operations, Alberto Garcia, 2015/10/08