On Thu, Jun 22, 2023, at 10:20 AM, Juergen Gross wrote:
> On 22.06.23 18:39, Andy Lutomirski wrote:
>> On Thu, Jun 22, 2023, at 3:33 AM, Juergen Gross wrote:
>>> On 22.06.23 10:26, Peter Zijlstra wrote:
On Thu, Jun 22, 2023 at 07:22:53AM +0200, Juergen Gross wrote:
> The hypercalls we
On 22.06.23 18:39, Andy Lutomirski wrote:
On Thu, Jun 22, 2023, at 3:33 AM, Juergen Gross wrote:
On 22.06.23 10:26, Peter Zijlstra wrote:
On Thu, Jun 22, 2023 at 07:22:53AM +0200, Juergen Gross wrote:
The hypercalls we are talking of are synchronous ones. They are running
in the context of th
On Thu, Jun 22, 2023, at 3:33 AM, Juergen Gross wrote:
> On 22.06.23 10:26, Peter Zijlstra wrote:
>> On Thu, Jun 22, 2023 at 07:22:53AM +0200, Juergen Gross wrote:
>>
>>> The hypercalls we are talking of are synchronous ones. They are running
>>> in the context of the vcpu doing the call (like a s
On 22.06.23 15:05, Andrew Cooper wrote:
On 22/06/2023 9:26 am, Peter Zijlstra wrote:
On Thu, Jun 22, 2023 at 07:22:53AM +0200, Juergen Gross wrote:
The hypercalls we are talking of are synchronous ones. They are running
in the context of the vcpu doing the call (like a syscall from userland is
On Thu, Jun 22, 2023 at 02:05:13PM +0100, Andrew Cooper wrote:
> On 22/06/2023 9:26 am, Peter Zijlstra wrote:
> > On Thu, Jun 22, 2023 at 07:22:53AM +0200, Juergen Gross wrote:
> >
> >> The hypercalls we are talking of are synchronous ones. They are running
> >> in the context of the vcpu doing the
On 22/06/2023 9:26 am, Peter Zijlstra wrote:
> On Thu, Jun 22, 2023 at 07:22:53AM +0200, Juergen Gross wrote:
>
>> The hypercalls we are talking of are synchronous ones. They are running
>> in the context of the vcpu doing the call (like a syscall from userland is
>> running in the process context)
On 22.06.23 13:15, Peter Zijlstra wrote:
On Thu, Jun 22, 2023 at 12:33:31PM +0200, Juergen Gross wrote:
On 22.06.23 10:26, Peter Zijlstra wrote:
The downside would be that some workloads might see worse performance
due to backend I/O handling might get preempted.
Is that an actual concern?
On Thu, Jun 22, 2023 at 12:33:31PM +0200, Juergen Gross wrote:
> On 22.06.23 10:26, Peter Zijlstra wrote:
> > > The downside would be that some workloads might see worse performance
> > > due to backend I/O handling might get preempted.
> >
> > Is that an actual concern? Mark this a legaxy intefa
On 22.06.23 10:26, Peter Zijlstra wrote:
On Thu, Jun 22, 2023 at 07:22:53AM +0200, Juergen Gross wrote:
The hypercalls we are talking of are synchronous ones. They are running
in the context of the vcpu doing the call (like a syscall from userland is
running in the process context).
(so time
On 6/21/2023 9:04 PM, Peter Zijlstra wrote:
> On Wed, Jun 21, 2023 at 07:19:21PM +, Per Bilse wrote:
>> On 6/21/2023 5:40 PM, Peter Zijlstra wrote:
>>> I don't understand it -- fundamentally, how can linux schedule when the
>>> guest isn't even running? Hypercall transfers control to the
>>> ho
On Thu, Jun 22, 2023 at 07:22:53AM +0200, Juergen Gross wrote:
> The hypercalls we are talking of are synchronous ones. They are running
> in the context of the vcpu doing the call (like a syscall from userland is
> running in the process context).
(so time actually passes from the guest's pov?)
On 21.06.23 22:04, Peter Zijlstra wrote:
On Wed, Jun 21, 2023 at 07:19:21PM +, Per Bilse wrote:
On 6/21/2023 5:40 PM, Peter Zijlstra wrote:
I don't understand it -- fundamentally, how can linux schedule when the
guest isn't even running? Hypercall transfers control to the
host/hypervisor an
On Wed, Jun 21, 2023, at 12:05 PM, Per Bilse wrote:
> On 6/21/2023 5:27 PM, Andy Lutomirski wrote:
>> This code is a horrible mess, with and without your patches. I think that,
>> if this were new, there's no way it would make it in to the kernel.
>
> Hi Andy, and many thanks for your frank as
On Wed, Jun 21, 2023 at 07:19:21PM +, Per Bilse wrote:
> On 6/21/2023 5:40 PM, Peter Zijlstra wrote:
> > I don't understand it -- fundamentally, how can linux schedule when the
> > guest isn't even running? Hypercall transfers control to the
> > host/hypervisor and leaves the guest suspended.
>
On 6/21/2023 5:40 PM, Peter Zijlstra wrote:
> I don't understand it -- fundamentally, how can linux schedule when the
> guest isn't even running? Hypercall transfers control to the
> host/hypervisor and leaves the guest suspended.
Hi Peter, as noted in earlier note to Andy, this is essentially exi
On 6/21/2023 5:27 PM, Andy Lutomirski wrote:
> This code is a horrible mess, with and without your patches. I think that,
> if this were new, there's no way it would make it in to the kernel.
Hi Andy, and many thanks for your frank assessments. Generally, this
is indeed somewhat old code, first
On Wed, Jun 21, 2023 at 03:14:42PM +, Per Bilse wrote:
> Some Xen hypercalls issued by dom0 guests may run for many 10s of
> seconds, potentially causing watchdog timeouts and other problems.
> It's rare for this to happen, but it does in extreme circumstances,
> for instance when shutting down
On Wed, Jun 21, 2023, at 8:14 AM, Per Bilse wrote:
> Some Xen hypercalls issued by dom0 guests may run for many 10s of
> seconds, potentially causing watchdog timeouts and other problems.
> It's rare for this to happen, but it does in extreme circumstances,
> for instance when shutting down VMs wit
Some Xen hypercalls issued by dom0 guests may run for many 10s of
seconds, potentially causing watchdog timeouts and other problems.
It's rare for this to happen, but it does in extreme circumstances,
for instance when shutting down VMs with very large memory allocations
(> 0.5 - 1TB). These hyper
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