> >>> 2) These mutexes are based on futexes which requires atomic > >>> operations in userspace. These are available on most > architectures. > > Look at > >>> 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. > > There is only a system call if there is congestion - that is > the whole idea behind the futex. > > >> And the > >> true atomic operation is in kernel not user space. > > "True" atomic operations are available in user space on most > architectures. > > >> Maybe > >> it's feasible > >> for other architectures to do atomic operations directly in user > >> space. > >> IMHO, not for powerpc. > > It is available for PowerPC, but not in POWER and POWER2 > instructionsets according to > 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. > > > > > Are you meaning that we didn't do atomic operations directly in user > > space > > on powerpc platform ? > > > > Well, that is not the conclusion I get either when reading > the glibc code. > Try to look at glibc-2.3.5/sysdeps/powerpc/bits/atomic.h. > > This is by the way probably what the original post in this > thread wanted > in the first place! > > 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
