User notification from Kernel mode driver

User notification from Kernel mode driver

Post by Jonathan de Boyne Pollar » Tue, 08 Aug 2000 04:00:00



CB> NT has a version of select() - WaitForMultipleObjects(), though
CB> the proper interface on Unix is poll() which is much better since
CB> select() shares the crippling feature of WaitForMultipleobjects()
CB> that it can only wait for a small number of objects.

That is not necessarily true.  Whether or not select() has such limitations on
the size of the file descriptor bitvectors depends from the exact flavour of
Unix being used.  On some Unices, the restriction has been lifted.

Read the answer to question 2.14 in the UNIX sockets programming FAQ
(http://www.faqs.org/faqs/unix-faq/socket/), the answer to question 2.1.1 in
the UNIX programming FAQ
(http://www.erlenstar.demon.co.uk/unix/faq_3.html#SEC29), and
http://www.purplet.demon.co.uk/linux/select/ .

 
 
 

User notification from Kernel mode driver

Post by Maxim S. Shatski » Tue, 08 Aug 2000 04:00:00


Quote:> CB> NT has a version of select() - WaitForMultipleObjects(), though

Nonsense.
select() semantics is - "wait on several communication channels till some
data will arrive to their buffers".
WFMO semantics is - "wait on several event objects".

NT has _no way_ of retrieving the event object for _arbitrary_ file handle
which will be signaled when data will arrive to the file's buffer.
You can select() on COM port and TCP socket in UNIX. You cannot do this in
NT - serial.sys does not support such an event.
So, select() in NT is for _sockets_ only.

    Max

 
 
 

1. kernel mode to user mode overhead

Does anyone have real world measure mentregarding the cost of making user to
kernel
mode transition? I am evaluating the possibility of porting some of the
fucntion into an FPGA
and would like to assess the performance of speed up from the hardware
implemenation.

Are there any reference out there?

Thanks,

Jimmy

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