Robert, I have a C benchmark program that opens a block device with O_DIRECT (040000 on x86 and 0200000 on arm) and reads/writes with 4K aligned buffers show up as BIOs as hoped. One easy way to "test" this is to add debug code to "dm-zero" and use it as a way to watch IOs as they get to the block stack. Doug On Mon, Jan 4, 2016 at 11:33 AM, Robert Kierski <rkierski@xxxxxxxx> wrote: > Hey Doug, > > I tried all sorts of things... even things that seemed rather backwards. I tried a variety of disk count's, chunk sizes, IO sizes, IO Counts, etc. > > Yes...the changes were adding the bi_iter (mostly). > > I also eliminated the limit of 10 printk's so that I could try various MDRaid configurations and various block size and counts without having to reboot. > > I would have thought that the OS would pass the IO from user space to the driver without modification. But it appears that's not the case. > > Bob Kierski > Senior Storage Performance Engineer > Cray Inc. > 380 Jackson Street > Suite 210 > St. Paul, MN 55101 > Tele: 651-967-9590 > Fax: 651-605-9001 > Cell: 651-890-7461 > -- Doug Dumitru EasyCo LLC -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
