On Fri, Aug 04, 2006 at 09:39:39PM -0600, Hans Reiser wrote: > > Please explain when cache flushes occur now. Without them enabled? Never. With them enabled on every commit and/or fsync. > For every fsync on a drive > that does not support write barriers? Which drives support it? Most IDE and SATA drives. > > Did this only get enabled now because it is only now that someone from > the press is paying attention to it? No, it has been enabled by default in the SUSE kernels for a long time (two enterprise releases now sles9 and sles10). I wanted to bring the discussion about it into mainline. > > This is the price we paid for losing Andre, yes? This is the price we pay for drives turning writeback cache on by default. It happens for performance, because without tagging write though caches give horrible write speeds. It is slower than not doing IO (writeback cache) but faster than turning writeback caches off. Exact benchmarks vary by drive, but it is never slower than write-through caching, and almost always faster. -chris - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
