Messages in this thread | | | Subject | Re: Merging relayfs? | From | Richard J Moore <> | Date | Mon, 18 Jul 2005 09:40:15 +0100 |
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Tom Zanussi <zanussi@us.ibm.com> wrote on 14/07/2005 16:01:25:
> The only things that are atomic are the counts of produced and > consumed buffers and these are only ever updated or read in the slow > buffer-switch path. They're atomic because if they weren't, wouldn't > it be possible for the client to read an unfinished value if the > producer was in the middle of updating it?
This depends on architecture. It is possible under some architectures to see the so-called score-boarding effect when reading on one processor while writing on another when not having imposed any atomicity. From memory, I believe this might be possible with zSeries, but I'll need to check the microarchitecture docs. It's been a long time since I read them but I do recall a reference to the score-boarding effect.
> ...
Richard
- - Richard J Moore IBM Advanced Linux Response Team - Linux Technology Centre MOBEX: 264807; Mobile (+44) (0)7739-875237 Office: (+44) (0)1962-817072
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