Re: [Xen-devel] [RFC 1/6] xen/arm: Re-enable interrupt later in the trap path

[Andrii Anisov <andrii.anisov@xxxxxxxxx>]

On 26.07.19 13:48, Julien Grall wrote:
> This is the 3rd time you send this patch... and still no proper explanation why 
> this is done nor the impact on keeping the interrupts disabled longer than 
> necessary.
I know it is the third time for this patch. Yet it is in the RFC series again.
In this series I think I need interrupts locked until I start time accounting 
for hypervisor. Time accounting is started by `tacc_head()` function. I prefer 
to have it called from C, because it is more convenient and obvious for those 
who are less familiar with the ARM code.

> Resending the patch without things addressed is only going to make it worst.
I'm still convinced the patch would improve interrupt latency for high 
interrupt rate use cases.
But I understand that I have no experiment to prove the effect, so I'm not 
willing to push through the patch.

Also, I have a question to you about another aspect of this patch. In the 
function `enter_hypervisor_head()` there is a check for a disabled workaround 
and turning it on. If we have the interrupts enabled until there, we have good 
chances to go through the interrupt processing `do_IRQ()` before WA enabled. Is 
it still OK?

--
Sincerely,
Andrii Anisov.

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