Re: [PATCH] Bug-fixes to enable PV ticketlock to work under Xen PVHVMwith Linux v3.12. (v1)

[David Vrabel]

On 07/09/13 14:46, Konrad Rzeszutek Wilk wrote:
> After a bit of false starts, lots of debugging, and tons of help from Stefano and
> David on how event mechanism is suppose to work I am happy to present a set
> of bug-fixes that make PV ticketlocks work under Xen PVHVM with Linux v3.12.
> 
> v3.12 has now thanks to commit 816434ec4a674fcdb3c2221a6dffdc8f34020550
> (Merge branch 'x86-spinlocks-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip)
> PV ticketlocks. That means:
>  - Xen PV bytelock has been replaced by Xen PV ticketlock.
>  - Xen PVHVM is using ticketlock (not PV variant) - this patch makes it PV.
>  - baremetal is still using ticketlocks.
> 
> In other words everything in the kernel is ticketlock based with the virtualizations
> having the 'PV' part to aid.
> 
> Please take a look at the patches. If you are interested in testing them
> out I will post a git tree on Monday based on v3.11 and v3.12-rc0. 
> 
> Note that I had not run any performance tests and I am not sure when I will
> be able to (got other bugs to squash now). I've asked our internal performance
> engineer to do some benchmarking - but those results won't be available for
> some time as it takes time to do good benchmarking.

If there was favourable performance data I would be happy for these to
go in 3.12, without I think they'll have to wait for 3.13.

David
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