Re: [Xen-devel] [for-4.7] x86/emulate: synchronize LOCKed instruction emulation

["Jan Beulich" <jbeulich@xxxxxxxx>]

>>> Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx> 04/14/16 6:00 PM >>>
>On 04/14/2016 06:44 PM, Jan Beulich wrote:
>> That's the performance effect on the hypervisor you talk about. But what 
>> about
>> the guest, which all of the sudden gets another domain wide lock applied?
>
>Well, yes, there's bound to be some performance loss - but I think the
>question is: is the added safety worth it? As always, there are
>trade-offs. I am quite possibly missing something, but surely a slightly
>slower, running guest is better than a fast unstable one.
>
>As for the patch, it's definitely perfectible, and I appreciate all
>suggestions to make it the best it can be (or even to scrape it for a
>better solution).

That's the while thing here: If what you have presented comes at a
reasonable price, we may well take it with obvious issues fixed. Yet if the
price is quite high, investing effort into finding a better solution is imo not
just warranted, but necessary.

Jan


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