Messages in this thread | | | Date | Fri, 07 Jan 2000 11:19:58 +0000 | From | Petko Manolov <> | Subject | Re: (*(unsigned long *)&jiffies)++; |
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Andrea Arcangeli wrote: > > On Fri, 7 Jan 2000, Petko Manolov wrote: > >AFAIK incl _lock_ the bus even without "lock" in fornt of the > >instruction > > The lock on the bus is _necessary_ in SMP. It would be very bad if each > incl would implicitly do a lock on the bus. It would forbid you to use > incl in SMP for single threaded code (for example inside critical > sections).
Lock don't hurt anyway. May be i am not right, but i think there was some simple instructions (not only incl) that force lock before them in both cases.
> Even if it would lock on the bus it wouldn't matter. C only knows about > signle threading. So as far as C is concerned it's fine if it doesn't use > incl for incrementing volatile variables IMHO.
I think so. The RISC-ifing make gcc optimize it as read, inc, write... But this tread become pointless ;-))
regards, Petkan
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