[Xen-devel] Re: [PATCH - resend] addition of loglevel for printf in Xen HV

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 26/10/06 2:30 pm, "Steven Rostedt" <srostedt@xxxxxxxxxx> wrote:

> So anything in between the upper and lower thresholds inclusive would be
> rate limited.  Also I'm not sure of the best way dom0 can communicate
> threshold changes to the hypervisor.  As well as if there should be a
> config to set the defaults.

I think yet-another-little-tool in dom0 is the right way to go. We can add a
sysctl to get/set the parameters. It can pretty-print the current parameters
and also provide a way of changing them. I don't think there's any benefit
to integration with xm -- it's not like this needs to be integrated with
xend or anything like that.

Yes, we should also have a way to set them as a boot parameter. I suggest we
should only enact those explicit parameters when dom0 starts to boot though
(no need to stop Xen being noisy in initial boot). We could have an extra
parameter (e.g., 'quiet') to override that if someone really cares.

It'd be nice to have debug-key support for changing it too, but actually
that's probably not so important if we have the dom0 tool.

Everything you said I agree with, so please do go hack it up. :-)

Another thought... By pushing the rate-limiting into printk() itself, we
lose the ability to print all-or-nothing for related blocks of printk (e.g.,
register dumps). We might want a 'same as previous line' specifier, which
would print/not-print same as previous output line?

 -- Keir

> So what are your thoughts?



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