On 12/13/2016 03:09 AM, Maciej W. Rozycki wrote:
On Tue, 13 Dec 2016, Leonid Yegoshin wrote:
Well, I prefer the collection of 3 flags:
flush_required - or flush to next level is required to force coherency
between this level and next after update of this level
invalidate_required - or invalidate is required to force coherency between
this level and next after update of next level
coherent_to_level - object is coherent with this level (only one domain of
coherency on this level is assumed)
A "flush" has always been an ambiguous term -- meaning anything from
"write-back", through "write-back+invalidate" to "invalidate". What is
"flush" is supposed to exactly mean here? If specifically any of the two
formers (the latter is obviously the other flag), then I suggest using the
respective name, or otherwise if it is meant to be generic "do what is
needed", then perhaps "synchronize" will work, like with the name of the
SYNCI instruction?
Well, I am not expert in choosing names, you know. I just would like to
make a distinguishing between "transfer data from this level to next
one" - any way - writeback or write-back-invalidate, and "clear data in
this level to be pulled on demand from next level".
This is an information purpose as Florian described, so details can be
skipped. The only useful info here - some efforts are needed after event
(see above) and that efforts are not cheap from performance point of view.
If we put here details then it is a long way because we need a lot of
details, see my original post. However, I would like to differ "flush"
and "invalidate" because it is triggered by different kind of event
(from upstream or from downstream).
- Leonid.
