On Mon, Apr 28, 2008 at 01:33:23PM -0600, Matthew Wilcox wrote: > On Mon, Apr 28, 2008 at 02:22:52PM -0500, Russ Anderson wrote: > > There is always an issue of how agressive the code should be on > > migrating pages. Should it migrate on the first correctable error, > > or wait for some threshold? Reasonable people may disagree on the > > threshold and the "right" answer may be hardware specific. The > > decision making is confined to the cpe_migrate.c code. It is > > currently set to migrate on the first correctable error. > > I think the kernel code should do the migration ASAP. But I think we > should have a list of 'bad' pages. We could then have a badram driver > that userspace can talk to to find out which pages are bad, map those > pages into a badram process, do various tests on them, and return the > pages to the pool if they're determined to be 'good'. Sure. The bad page list is badpagelist (defined in mca.c). > I could also see badramd having a list of pages found to be bad > in previous boots and asking the badram driver to take them out of > circulation early in boot before they've been allocated. That would be one alternative. That type functionality would be useful. FWIW, some of my testing was on a system with a DIMM with solid single bits. It is a row/column problem so several meg of addresses are effected. Each boot it would migrate several meg worth of pages without any problem. It works surprisingly good. -- 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
|