On Wed, Jun 04, 2014 at 08:18:42AM -0600, Jens Axboe wrote: > A null_blk test is the absolute best case for percpu_ida, since > there are enough tags and everything is localized. The above test is > more useful for testing blk-mq than any real world application of > the tagging. > > I've done considerable testing on both 2 and 4 socket (32 and 64 > CPUs) and bitmap tagging is better in a much wider range of > applications. This includes even high tag depth devices like nvme, > and more normal ranges like mtip32xx and scsi-mq setups.
Just for the record: bitmap tags on a 48 CPU box with NVMe device indeed shows almost the same performance/cache rate as the stock kernel. -- Regards, Alexander Gordeev agord...@redhat.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
