[Xen-devel] Re: [PATCH 13/14] x86/ticketlock: add slowpath logic

[Srivatsa Vaddagiri <vatsa@xxxxxxxxxxxxxxxxxx>]

On Wed, Jan 19, 2011 at 10:31:06AM -0800, Jeremy Fitzhardinge wrote:
> I think you're probably right; when I last tested this code, it was
> hanging in at about the rate this kind of race would cause.  And in my
> previous analysis of similar schemes (the current pv spinlock code), it
> was always correct to do the "slowpath" test after doing do the unlock.
> 
> *But* I haven't yet had the chance to specifically go through and
> analyse your patch in detail to make sure there's nothing else going on,
> so take this as provisional.
> 
> How much testing have you given it?

I have tested quite extensively with booting a 16-vcpu guest (on a 16-pcpu host)
and running kernel compine (with 32-threads). Without this patch, I had
difficulty booting/shutting-down successfully (it would hang mid-way).

- vatsa

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