[vbox-dev] Driver ISR call delayed for device interrupts

Ramshankar ramshankar.venkataraman at oracle.com
Wed Jun 15 07:38:23 UTC 2016

On 06/15/2016 08:51 AM, llyzs wrote:
> Hi Devs,
> I have a virtual PCI device added on VirtualBox OSE and a driver which 
> sends I/O to do some stuff in the host and receive interrupts when the 
> work is done. The interrupts work most of the time, however there are 
> random delays between PDMDevHlpPCISetIrq is called and the driver ISR 
> is called. Most of the time there is no delay (<1ms) but periodically 
> there is a delay from 10+ms to even 60+ms. One more strange thing is 
> that the delay mostly happen at exactly every 500ms. So anyone can 
> give me some hint on what is causing the interrupt delay? What kind of 
> job inside VirtualBox that runs every 500ms that might be causing 
> interrupt delay?
> I am on Windows 8.1 x64 (both guest and host). Thanks in advanced.

Just curious, have you tried this with the VirtualBox 5.1 beta? The APIC 
and I/O APIC implementations in VirtualBox were completely re-done and 
it resulted in fixing long-standing problems of the nature you describe 
(for e.g., EOI on level-triggered interrupts not causing the I/O APIC to 
immediately pickup pending interrupts until another interrupt arrives 
and a few others problems).


> Vic
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