It's still not clear to me why the default value here is large
enough Solaris. I hit this limit again when setting up 120 SATA
drives configured as 15 raidz2 groups each containing 8 drives.
We expect to go bigger so we may just want to spend a little
time and figure out how to make this all dynamic.
SLES10 ships util-linux-2.12r-35.30 which does not support the -f option
to losetup. To avoid this problem the unused_loop_device() function was
added which attempts to find an unused loop device by checking each
/dev/loop* device with losetup to see if it is configured.
While the generic atomic implementation is not used by default
for x86_64 or x86 builds, we still need to always build it with
-fPIC if we ever want to use it on these platforms.
Futher testing on my powerpc system revealed that the powerpc
specific atomic implemetation was flawed. Rather than spending
a lot of time correctly reimplementing it in assembly I have
reworked it in to a 100% generic version. The generic version
will not perform well but it does provide correct sematics. It
will be used only when there is no architecture specific version
available. These changes do not impact x86_64 and x86 which have
have correct native implementations.
The intent here is to fully remove the previous Solaris thread
implementation so we don't need to simulate both Solaris kernel
and user space thread APIs. The few user space consumers of the
thread API have been updated to use the kthread API. In order
to support this we needed to more fully support the kthread API
and that means not doing crazy things like casting a thread id
to a pointer and using that as was done before. This first
implementation is not effecient but it does provide all the
corrent semantics. If/when performance becomes and issue we
can and should just natively adopt pthreads which is portable.
Let me finish by saying I'm not proud of any of this and I would
love to see it improved. However, this slow implementation does
at least provide all the correct kthread API semantics whereas
the previous method of casting the thread ID to a pointer was
dodgy at best.
Ricardo M. Correia
Brian Behlendorf