Re: [PATCH][2.5] Protect smp_call_function_data w/ spinlocks on Alpha

From: Richard Henderson (rth@twiddle.net)
Date: Mon Feb 17 2003 - 03:15:44 EST


On Fri, Feb 14, 2003 at 12:16:12PM -0500, Zwane Mwaikambo wrote:
> Ok the reason being is that the lock not only protects the
> smp_call_function_data pointer but also acts as a lock for that critical
> section. Without it you'll constantly be overwriting the pointer halfway
> through IPI acceptance (or even worse whilst a remote CPU is assigning the
> data members).

Really. Show me the sequence there?

I happen to like the pointer_lock a lot, and think we should
make more use of it on systems known to have cmpxchg. It
saves on the number of cache lines that have to get bounced
between processors.

r~
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