usb isr timing

NTDEV
1

Hi,

? I work with a PCIe device which registers a line-based interrupt. This IRQ can be shared with the USB ports. Today, xperf showed that the time spent on the ISR for the USB is 5 us. Since there are 2 USB ports sharing the line with the device, the time spent on ISR processing can be delayed with 10 us.?This is confirmed by disabling the USB ports.

? I would like to know if there’s a way to put my ISR on top of the shared IRQ list. Could LoadOrderGroup influence this behaviour? The operating system is Vista 32 bit.

? Thanks for taking the time to answer this question.

Regards,
? Calin

2

You can’t control this.LoadOrderGroup is only for boot start drivers load ordering, not for start ordering.

d

debt from my phone

From: Calin Iaru
Sent: 2/21/2012 10:54 AM
To: Windows System Software Devs Interest List
Subject: [ntdev] usb isr timing

Hi,

I work with a PCIe device which registers a line-based interrupt. This IRQ can be shared with the USB ports. Today, xperf showed that the time spent on the ISR for the USB is 5 us. Since there are 2 USB ports sharing the line with the device, the time spent on ISR processing can be delayed with 10 us. This is confirmed by disabling the USB ports.

I would like to know if there’s a way to put my ISR on top of the shared IRQ list. Could LoadOrderGroup influence this behaviour? The operating system is Vista 32 bit.

Thanks for taking the time to answer this question.

Regards,
Calin

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3

Hi Doron,
?
? thank you. LoadOrderGroup is set to NDIS in the WinDDK\7600.16385.1\src\general\pcidrv\kmdf\HW$(O)\netdrv.inf?and the?StartType is 3. The documentation says that drivers with SERVICE_DEMAND_START have LoadOrderGroup ignored. That’s one of the reasons why I asked about LoadOrderGroup.
?
Regards,
? Calin

From: Doron Holan
To: Windows System Software Devs Interest List
Sent: Tuesday, February 21, 2012 8:02 PM
Subject: RE: [ntdev] usb isr timing

You can’t control this.LoadOrderGroup is only for boot start drivers load ordering, not for start ordering.

d

debt from my phone