On Fri, Aug 06, 2010 at 01:55:21PM +0200, Jens Axboe wrote: > On 2010-08-05 16:51, Chris Mason wrote: > > And then we need to setup a fio job file that hammers on all the ssds at > > once. I'd have it use adio/dio and talk directly to the drives. I'd do > > something like this for the fio job file, but Jens Axboe is cc'd and he > > might make another suggestion on the job file. I'd do something like > > this in a file named ssd.fio > > > > [global] > > size=32g > > direct=1 > > iodepth=8 > > iodepth=8 will have no effect if you don't also set a different IO > engine, otherwise you would be using read(2) to fetch the data. So add > ioengine=libaio to take advantage of a higher queue depth as well.
Yeah, I just realized I messed up the suggested file, but it worked well enough on the block devices, so I think just having 16 procs hitting the array was enough. libaio will only help with O_DIRECT though, so this only applies to 2.6.35 as well. > > Also, I didn't see Chris mention this, but if you have a newer intel box > you can use hw accellerated crc32c instead. For some reason my test box > always loads crc32c and not crc32c-intel, so I need to do that manually. > That helps a lot with higher transfer rates. You can check support for > hw crc32c by checking for the 'sse4_2' flag in /proc/cpuinfo. Yeah, the HW assisted crc does make a huge difference. -chris -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
