PacketSendPackets and latency

["David Atkins" <david () suitcasetv com>]

Hi,

 

I'm trying to send test data using the PacketSendPackets() function using
Sync = true, this works great except that I am getting a large latency when
making back to back calls, sending a 30Mbyte buffer results in the send
packet timing being really accurate but that the time spent entering the
call is significant and if I send back to back buffers I get 13ms of pause
between bursts of packets. 

 

I assume it's because the DeviceIOCOntrol request is copying my request to a
buffer but the IOCTL command used is #define  BIOCSENDPACKETSSYNC (9033)
which decodes as Direct IO for the input which suggest that no copy needs to
be made to buffer data into the driver. I may have misread the way this
works but had expected that the driver would memory map the pointer in and
work directly but the time taken suggests a copy is happening.

 

Anyone had similar experiences?

 

David

 

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