Subject: Re: memsync/cacheflush proposals: status
To: None <email@example.com, firstname.lastname@example.org>
From: Wolfgang Solfrank <email@example.com>
Date: 02/09/1999 16:08:21
one minor nit:
> - I did a bit code and manual browsing myself and noticed that mmap() can
> be told to make the region semaphore-safe, which would make userland
> memory barriers for userland semaphores (as implemented using CAS/CAS2 on m68k
> or maybe the reservation stuff on PPC) unneeded. Multi-CPU machines that
> do NOT provide coherency in hardware should be thr^H^H^Htaught to make share
> regions uncached, maybe... you'll have a performance penalty in either case.
If you are looking for a semaphore mechanism on PPC independent from the
particular implementation of the cpu, there is _no_ possibility to do
this without the use of lwarx/stwcx.. No, making the shared regions
uncached/guarded etc. isn't sufficient.
ws@TooLs.DE (Wolfgang Solfrank, TooLs GmbH) +49-228-985800