Low latency OID/Communication

NTDEV
1

Hi,
How can I create a low latency request from the application to the miniport device driver?
When I send a regular OID request I see delays of 15ms.

Thanks,
Shai

2

Since 15ms is the typical timer resolution of Windows, maybe the first
question is how do you measure the latency?

Don Burn
Windows Filesystem and Driver Consulting
Website: http://www.windrvr.com
Blog: http://msmvps.com/blogs/WinDrvr

“xxxxx@gmail.com” wrote in message
news:xxxxx@ntdev:

> Hi,
> How can I create a low latency request from the application to the miniport device driver?
> When I send a regular OID request I see delays of 15ms.
>
> Thanks,
> Shai

3

On 13-Mar-2012 23:37, Don Burn wrote:

Since 15ms is the typical timer resolution of Windows, maybe the first
question is how do you measure the latency?

… and how you “send” the OID request from application?
– pa

“shai.ostshega” <> wrote in message
news:xxxxx@ntdev:

> Hi,
> How can I create a low latency request from the application to the
> miniport device driver?
> When I send a regular OID request I see delays of 15ms.
>
> Thanks,
> Shai

4

OIDs are not meant for low-latency (less than ~100 millisecond deadline) communication. They are serialized against other OIDs, which means that your “fast” OID can always get stuck behind another “slow” OID; that’s outside the control of the usermode app or the miniport.

If you really need low-latency communication, you’ll have to create a device object and send IOCTLs. This technique isn’t specific to NDIS or networking, and you’ll find lots of discussion on it in the archives here.