> > It's not just 386 vs later due to cmpxchg. It's also the simple issue of
> > UP vs SMP - a UP system still wants to do locking, but it doesn't need the
> > lock prefix. And that lock prefix makes a _huge_ difference
> > performance-wise.
>
> Fail to see why that matters. User level locking is mostly beneficial on SMPs.
> So, you lock the bus for the atomic update. This is UP, nothing's going on
> on the bus anyway.
Lots of older x86 is too stupid to optimise exclusive cache line locked
operations. After all the bus is still shared - PCI bus masters for one
Alan
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This archive was generated by hypermail 2b29 : Fri Mar 15 2002 - 22:00:10 EST