On 04/08/2015 10:19 PM, Mark Nelson wrote:
On 04/07/2015 09:58 PM, Sage Weil wrote:
What would be very interesting would be to see the 4KB performance
with the defaults (newstore overlay max = 32) vs overlays disabled
(newstore overlay max = 0) and see if/how much it is helping.

And here we go.  1 OSD, 1X replication.  16GB RBD volume.

4MB        write    read    randw    randr
default overlay    36.13    106.61    34.49    92.69
no overlay    36.29    105.61    34.49    93.55

128KB        write    read    randw    randr
default overlay    1.71    97.90    1.65    25.79
no overlay    1.72    97.80    1.66    25.78

4KB        write    read    randw    randr
default overlay    0.40    61.88    1.29    1.11
no overlay    0.05    61.26    0.05    1.10


Update this morning. Also ran filestore tests for comparison. Next we'll look at how tweaking the overlay for different IO sizes affects things. IE the overlay threshold is 64k right now and it appears that 128K write IOs for instance are quite a bit worse with newstore currently than with filestore. Sage also just committed changes that will allow overlay writes during append/create which may help improve small IO write performance as well in some cases.

4MB             write   read    randw   randr
default overlay 36.13   106.61  34.49   92.69
no overlay      36.29   105.61  34.49   93.55
filestore       36.17   84.59   34.11   79.85
                                
128KB           write   read    randw   randr
default overlay 1.71    97.90   1.65    25.79
no overlay      1.72    97.80   1.66    25.78
filestore       27.15   79.91   8.77    19.00
                                
4KB             write   read    randw   randr
default overlay 0.40    61.88   1.29    1.11
no overlay      0.05    61.26   0.05    1.10
filestore       4.14    56.30   0.42    0.76

Seekwatcher movies and graphs available here:

http://nhm.ceph.com/newstore/20150408/

Note for instance the very interesting blktrace patterns for 4K random writes on the OSD in each case:

http://nhm.ceph.com/newstore/20150408/filestore/RBD_00004096_randwrite.png
http://nhm.ceph.com/newstore/20150408/default_overlay/RBD_00004096_randwrite.png
http://nhm.ceph.com/newstore/20150408/no_overlay/RBD_00004096_randwrite.png

Mark
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