Re: [PATCH RFC V9 0/19] Paravirtualized ticket spinlocks
From: Raghavendra K T
Date: Wed Jul 10 2013 - 07:25:02 EST
On 07/10/2013 04:17 PM, Gleb Natapov wrote:
On Wed, Jul 10, 2013 at 12:40:47PM +0200, Peter Zijlstra wrote:
On Wed, Jul 10, 2013 at 01:33:25PM +0300, Gleb Natapov wrote:
Here's an idea, trim the damn email ;-) -- not only directed at gleb.
Good idea.
Ingo, Gleb,
From the results perspective, Andrew Theurer, Vinod's test results are
pro-pvspinlock.
Could you please help me to know what will make it a mergeable
candidate?.
I need to spend more time reviewing it :) The problem with PV interfaces
is that they are easy to add but hard to get rid of if better solution
(HW or otherwise) appears.
How so? Just make sure the registration for the PV interface is optional; that
is, allow it to fail. A guest that fails the PV setup will either have to try
another PV interface or fall back to 'native'.
We have to carry PV around for live migration purposes. PV interface
cannot disappear under a running guest.
IIRC, The only requirement was running state of the vcpu to be retained.
This was addressed by
[PATCH RFC V10 13/18] kvm : Fold pv_unhalt flag into GET_MP_STATE ioctl
to aid migration.
I would have to know more if I missed something here.
I agree that Jiannan's Preemptable Lock idea is promising and we could
evaluate that approach, and make the best one get into kernel and also
will carry on discussion with Jiannan to improve that patch.
That would be great. The work is stalled from what I can tell.
I absolutely hated that stuff because it wrecked the native code.
Yes, the idea was to hide it from native code behind PV hooks.
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