On 10/21/2010 12:13 PM, Nayak, Rajendra wrote:
<snip>
Hi Kevin,
What the patch does is reprogram's the sysc value (from the cache)
whenever its lost. So its infact saved in the cache and restored when
needed.
Otherwise, all this patch does is refresh the _sysc_cache with
completely unknown contents. It also somewhat defeats the purpose of
having a cache. If you're going to read SYSC in order to determine
whether or not you can avoid a write, you might as well just blindly
write.
I thought of this and dismissed it thinking I would end up with a read/or/write
and instead a read always to avoid write is better.
But now looking back again, it does make sense to still keep the cache to avoid
a read (since a read has significantly more latency than write) and do a blind write
always. Does that make sense?
That seems indeed better. The point is that cache is already a location
for the "save" part.
So writing blindly will do the restore with always the good value.
It is anyway faster than trying to check if we lost context or not
through PRM registers.
Benoit
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