On Tue, Oct 14, 2008 at 2:14 AM, kenneth johansson <ken@xxxxxxxxx> wrote: ... > All my numbers comes from using 1MB blocks. but I'm not using dd. > After removing the logic that actually put some data into the buffers I > do get about 105 MB/sec using O_DIRECT. Ok. Good. > I'm doing a full disk write now to get a reference plot. See http://hdperf.sourceforge.net/ and http://nathan.laredo.name/hdperf/ Simple tool to (relatively) quickly measure the perf across the disk platter. > Not using O_DIRECT should be almost identical. *should* - but there are known problems with writeback. Some of them are described nicely by Dave Chinner as "Random Thought #3": http://iou.parisc-linux.org/lsf2008/linux_storage_scalability-Dave_Chinner.odp Look for "writeback" for a summary of the discussion: http://iou.parisc-linux.org/lsf2008/SUMMARY-Storage.txt hth, grant -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
