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Re: [Xen-devel] [PATCH v3 3/3] tools: introduce parameter max_wp_ram_ranges.
- To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxx>
- From: "Tian, Kevin" <kevin.tian@xxxxxxxxx>
- Date: Wed, 17 Feb 2016 09:58:16 +0000
- Accept-language: en-US
- Cc: Wei Liu <wei.liu2@xxxxxxxxxx>, Ian Campbell <Ian.Campbell@xxxxxxxxxx>, Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>, George Dunlap <dunlapg@xxxxxxxxx>, Zhang Yu <yu.c.zhang@xxxxxxxxxxxxxxx>, George Dunlap <George.Dunlap@xxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxx>, Stefano Stabellini <Stefano.Stabellini@xxxxxxxxxx>, "Lv, Zhiyuan" <zhiyuan.lv@xxxxxxxxx>, Ian Jackson <Ian.Jackson@xxxxxxxxxx>, "Keir \(Xen.org\)" <keir@xxxxxxx>
- Delivery-date: Wed, 17 Feb 2016 09:58:27 +0000
- List-id: Xen developer discussion <xen-devel.lists.xen.org>
- Thread-index: AQHRX+/DGYZZ2/WMzUmIfvb5dHRHGJ8cqAcAgAAeu4CAAAK0AIARizag//+TeICAABzygIAAClwAgAGR50D//9togIAAlXjg
- Thread-topic: [Xen-devel] [PATCH v3 3/3] tools: introduce parameter max_wp_ram_ranges.
> From: Paul Durrant [mailto:Paul.Durrant@xxxxxxxxxx]
> Sent: Wednesday, February 17, 2016 4:58 PM
>
> >
> > btw does this design consider the case where multiple ioreq servers
> > may claim on same page?
>
> Yes it does and there are currently insufficient page types to allow any more
> than a single
> ioreq server to claim a type. My plan is that, in future, we can add a p2t
> mapping table to
> allow for more types and then introduce HVMMEM_ioreq_1, HVMMEM_ioreq_2, etc.
so these new types actually represent ioreq server ID, right? If yes I can then
understand your earlier explanations.
>
> > For example, different usages may both
> > want to capture write requests on the same set of pages (say XenGT
> > selectively write-protects a subset of pages due to shadow GTT, while
> > another agent wants to monitor all guest writes to any guest memory
> > page).
>
> Monitoring is a different thing altogether. Emulation is costly and not
> something you'd want
> to use for that purpose. If you want to monitor writes then log-dirty already
> exists for that
> purpose.
Agree.
>
> >
> > Thanks
> > Kevin
>
> I hope my explanation helped. I think things will be clearer once I've had
> chance to actually
> put together a design doc. and hack up a PoC (probably only for EPT at first).
>
Thanks for the help. Let's see whether we can have some solution ready for 4.7.
:-)
Thanks
Kevin
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