Re: [Xen-devel] [PATCH 1/2] trace: improve usefulness of hypercall trace record

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Thu, May 24, 2012 at 11:37 AM, David Vrabel <david.vrabel@xxxxxxxxxx> wrote:
> From: David Vrabel <david.vrabel@xxxxxxxxxx>
>
> Trace hypercalls using a more useful trace record format.
>
> The EIP field is removed (it was always somewhere in the hypercall
> page) and include selected hypercall arguments (the number of calls in
> a multicall, and the number of PTE updates in an mmu_update).
>
> To allow tracing tools to distinguish between the two formats, the new
> format uses a new event ID (TRC_PV_HYPERCALL_V2).
>
> Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>

The problem with tracing all the hypercall arguments is that it will
significantly increase the size of traces.  How many arguments to most
hypercalls actually use -- and how many of those are actually just
pointers to guest memory, and useless in a trace record anyway?

 -George

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