On Fri, Jun 03, 2016 at 06:28:17PM -0400, Waiman Long wrote: > Since all the DAX I/Os are synchronous, there is no need to update > the DIO count in dax_do_io() when the count has already been updated > or the i_rwsem lock (read or write) has or will be taken. > > This patch passes in the DIO_SKIP_DIO_COUNT flag to dax_do_io() to > disable two unneeded atomic operations that can slow thing down in > fast storages like NVDIMM. > > With a 38-threads fio I/O test with 2 shared files (on DAX-mount ext4 > formatted NVDIMM) running on a 4-socket Haswell-EX server with 4.6-rc1 > kernel, the aggregated bandwidths before and after the patch were: Please do the right thing and remove the code to call inode_dio_begin / inode_dio_end entirely. There is nothing ext4 specific about the dax code being synchronous. Together with my previous suggestion that also allows dropping the flags argument. Then as a next step remove the end_io argument and just call it in the callers which is perfectly safe again as dax is synchronous. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
