Mohammad Nayyer Zubair wrote:
Hi all,
I am working on this process which has a lot of pthreads (around 25)
and 4 of them issue a lot of ioctl calls to my kernel module. I notice
that as more pthreads start issuing ioctls, system performance
decreases.
These threads are writing data to Fibre-Channel attached scsi storage.
Is it possible the ioctls are slowing down the entire system, not just
the usermode process?
yes - possibly, esp considering existence of these:
[PATCH] macros to detect existance of unlocked_ioctl and ioctl_compat
*From: *Michael S. Tsirkin
*Date: * Thu Jan 06 2005 - 09:06:51 EST
from the unlocked_* version, Id guess that lock you observed below is
the BKL,
and it certainly could be a choke point, esp as youre getting many
calls to the ioctl.
I see sys_ioctl() does a lock_kernel()
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