Subject: FD_LOCK, pthreads and drivers
To: None <tech-kern@netbsd.org>
From: mike varga <mike.varga@cavium.com>
List: tech-kern
Date: 09/13/2001 14:27:02
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I noticed that while testing the driver I wrote
for a crypto device, that only one thread
can be executing within the context of
my driver at a time.
The problem is that the pthreads library=20
replaces the ioctl with another that exclusively
locks the file descriptor with calls to FD_LOCK/
FD_UNLOCK.
Why?
I went to extremes to make sure that it
would be fully reentrant.
The driver/crypto accelerator now suffers
from slow performance.=20
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<DIV><FONT face=3DArial size=3D2>I noticed that while testing the driver =
I=20
wrote</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>for a crypto device, that only one=20
thread</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>can be executing within the context =
of</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>my driver at a time.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>The problem is that the pthreads =
library=20
</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>replaces the ioctl with another that=20
exclusively</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>locks the file descriptor </FONT><FONT =
face=3DArial=20
size=3D2>with calls to FD_LOCK/</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>FD_UNLOCK.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Why?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2> I went to extremes to make sure =
that=20
it</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>would be fully reentrant.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>The driver/crypto accelerator now=20
suffers</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>from slow performance. =
</FONT></DIV></BODY></HTML>
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