On Wed, Nov 29, 2006 at 04:05:35PM -0600, Sam Lang wrote: > I had a note that we should change the default aio data-sync code to > only sync at the end of an IO request, instead of for each trove > operation (in FlowBufferSize chunks). Doing this at the end of an > io.sm seemed a little messy, but if/when we have request ids (hints) > being passed to the trove interface, we could use that as a way to > know to flush at the end. In any case, it sounds like its better to > flush early and often than at the end of a request?
I have no data to back this up but it feels like flushing early and often will help only if you have a good disk subsystem. > From a user perspective, we usually tell people to enable data sync > if they're concerned about losing data. Now we're talking about > getting better performance with data sync enabled (at least in some > cases). > Does it make sense to sync even with data sync disabled if > we can figure out that better performance would result? I can't imagine a use case where someone would be upset if we were able to both deliver better performance and also sync data even if they didn't ask us to. If we can figure out what's best (maybe with a quick test when the server starts up?), then yes, sync even with sync disabled. ==rob -- Rob Latham Mathematics and Computer Science Division A215 0178 EA2D B059 8CDF Argonne National Lab, IL USA B29D F333 664A 4280 315B _______________________________________________ Pvfs2-developers mailing list Pvfs2-developers@beowulf-underground.org http://www.beowulf-underground.org/mailman/listinfo/pvfs2-developers
