Re: [Xen-devel] [PATCH] switch rangeset's lock to rwlock

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 30.09.14 at 22:53, <keir.xen@xxxxxxxxx> wrote:
> Do the searches ever get long enough that a read lock helps? If any of 
> the rangesets is getting large and making the searches slow then it 
> would be quite easy to switch from linked list to red-black tree?

As noted elsewhere, even very brief locking periods can cause
convoys for many-vCPU guests. One case where we observe
this is hvm_get_guest_time_fixed() (without clear route for
mitigation as converting to rw lock is not an option here, and I
didn't get around to try out whether eliminating the lock
altogether in favor of atomic CPU operations would make this
any better).

Jan


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