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2) These mutexes are based on futexes which requires atomic=20
operations in userspace. These are available on most=20

architectures.

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Look at

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the glibc code in
nptl/sysdeps/unix/sysv/linux/powerpc/lowlevellock.h for instance.
Use that and your PPC manual to implement your atomic operations.

No matter semaphore or futex, it uses system calls to kernel.

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There is only a system call if there is congestion - that is=20
the whole idea behind the futex.
=20

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And the
true atomic operation is in kernel not user space.

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"True" atomic operations are available in user space on most=20
architectures.
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Maybe
it's feasible
for other architectures to do atomic operations directly in user=20
space.
IMHO, not for powerpc.

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It is available for PowerPC, but not in POWER and POWER2=20
instructionsets according to=20
http://www.nersc.gov/vendor_docs/ibm/asm/lwarx.htm#idx607
It is the same in the ARM world: Atomic instructions was introduced in
ARMv6 I believe. Older ARM processors don't have them.
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Are you meaning that we didn't do atomic operations directly in user
space
on powerpc platform ?

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Well, that is not the conclusion I get either when reading=20
the glibc code.
Try to look at glibc-2.3.5/sysdeps/powerpc/bits/atomic.h.
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This is by the way probably what the original post in this=20
thread wanted=20
in the first place!
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Esben

I totally agree with you and Brant about it. I don't believe we cannot
do the atomic operation in user space on powerpc.

-DAve=20