On Thu, Aug 25, 2016 at 10:38:34PM +1000, Paul Mackerras wrote: > On Mon, Mar 21, 2016 at 02:53:07PM +1100, David Gibson wrote: > > This is an implementation of the kernel parts of the PAPR hashed page > > table (HPT) resizing extension. > > > > It contains a complete guest-side implementation - or as complete as > > it can be until we have a final PAPR change. > > > > It also contains a draft host side implementation for KVM HV (the KVM > > PR and TCG host-side implementations live in qemu). This works, but > > is very slow in the critical section (where the guest must be > > stopped). It is significantly slower than the TCG/PR implementation; > > unusably slow for large hash tables (~2.8s for a 1G HPT). > > > > I'm still looking into what's the cause of the slowness, and I'm not > > sure yet if the current approach can be tweaked to be fast enough, or > > if it will require a new approach. > > I have finally managed to have a close look at this series. The > approach and implementation seem basically sane,
Ok, good to know.
> though I think the
> rehash function could be optimized a bit. I also have an optimized
> implementation of hpte_page_size() and hpte_base_page_size() which
> should be a lot quicker than the 2d linear (areal?) search which we do
> at present.
Ok, sounds like with those optimizations this approach might be good
enough. I aim to send a revised version of these some time after the
RHEL 7.3 crunch.
In the meantime, any word on the PAPR proposal?
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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