On Wed, Feb 27, 2008 at 04:53:32AM -0600, Robin Holt wrote: > > Russ, do you know what the max number of MCA/INIT records we would > expect to see during a worst-case type event? At least NR_CPUS. In the case of an nmi of the systen, for example, there will be an INIT record for each CPU. SAL is expected to create a record for each CPU. I think the real question is how many MCA/INIT records will linux process at one time. For both MCA and INIT, the CPUs are rendezvoused one CPU becomes the monarch, so there is only one CPU calling down to SAL at a time. Even in the case of multiple CPUs going into MCA at the same time the handling is done one CPU at a time (after the first CPU handles its MCA it is demoted to a slave and the next CPUs promoted to monarch to handle its MCA). That said, the more parallel the processing of records, the more buffering will be needed. There is the potential for nested MCAs one a given CPU that should be handled. Since CPUs are rendezvoued, it is extremely unlikely to have more that one layer of nesting (two MCA records). Nested CPEI/CMCI are more likely. Since the handling of those interrupts is done with interrupts enabled (per the MCA Spec) there is a greater potential for multiple records per CPU being processed at the same time. A big part of the issue is how quickly salinfo able to process records. The quicker it handles the records, the less buffering is needed. Since salinfo is running in userland, it can get held off for long periods of time. -- Russ Anderson, OS RAS/Partitioning Project Lead SGI - Silicon Graphics Inc rja@xxxxxxx - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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