lkml.org 
[lkml]   [2011]   [Oct]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH RFC V2 3/5] kvm hypervisor : Add two hypercalls to support pv-ticketlock
On 10/24/2011 02:27 PM, Srivatsa Vaddagiri wrote:
> Good point. Assuming yield_on_hlt=1, that would allow the vcpu to be put
> to sleep and let other vcpus make progress.
>
> I guess with that change, we can also dropthe need for other hypercall
> introduced in this patch (kvm_pv_kick_cpu_op()). Essentially a vcpu sleeping
> because of HLT instruction can be woken up by a IPI issued by vcpu releasing a
> lock.

Not if interrupts are disabled. My original plan was to use NMIs for
wakeups, but it turns out NMIs can be coalesced under certain rare
circumstances; this requires workarounds by the generic NMI code that
make NMIs too slow.

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.



\
 
 \ /
  Last update: 2011-10-24 15:13    [from the cache]
©2003-2011 Jasper Spaans