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Subject: Re: [PATCH 2/2] powerpc,kexec: Speedup kexec hpte tear down
From: Michael Ellerman <michael@ellerman.id.au>
To: Michael Neuling <mikey@neuling.org>
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Date: Wed, 12 May 2010 11:36:11 +1000
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Cc: kexec@lists.infradead.org, Paul Mackerras <paulus@samba.org>,
	Anton Blanchard <anton@samba.org>, linuxppc-dev@ozlabs.org
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On Wed, 2010-05-12 at 11:06 +1000, Michael Neuling wrote:
> > > We probably only do the remove on < 1% of the hptes now.  So I doubt =
we
> > > would get a speedup since most of the time we aren't do the remove
> > > anymore.
> >=20
> > It would be nice to have some actual numbers.  Could you add some
> > counters and print the results at the end?  (Or don't you have any
> > way to print things at that stage?)
>=20
> Printing is hard at that point but I think we can do it.  I'll try to
> when I get some time.

A version of udbg_putcLP() that uses a raw hcall should work, or there
was code added to purgatory recently to print to the HV console which
you could nick.

> A heavily loaded system which kdumps will need a lot more hptes removes
> than kexec, so stats for both these cases might be useful also.

Yeah, or even a system that is kexec'ed while lots of stuff is still
running.

cheers



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