On 04/17/2015 10:46 AM, Sage Weil wrote:
> On Fri, 17 Apr 2015, Mark Nelson wrote:
>> On 04/16/2015 07:38 PM, Sage Weil wrote:
>> Absolutely!  I'll get some tests running now.  Looks like everyone is jumping
>> on the libaio bandwagon which naively seems like the right way to me too.  Can
>> you talk a little bit more about how you'd see fdatasync work in this case
>> though vs the threaded implementation?
>
> That I'm not certain about, not sure if I need O_DSYNC or if the libaio
> fsync hook actually works; the docs are ambiguous.

Ran tests with 8 WAL threads and compared to filestore numbers.  This is 
using the Xiaoxi tunables.  Things are definitely looking better on 
spinning disks.  Random writes even without the SSD WAL are far more 
comparable to filestore than previously.  Sequential writes are better 
but still sometimes quite a bit worse.

PCIe SSD numbers have improved marginally, but still far below filestore.

Mark