[lustre-discuss] More issues with cur_grant_bytes

Kevin M. Hildebrand kevin at umd.edu
Tue Dec 8 10:46:04 PST 2020


We appear to be tripping over the same issues reported recently by Tung-Han
Hsieh and Simon Guilbault, namely that cur_grant_bytes is being reduced to
a very small value and causing abysmal performance.

For example, OSTs 0, 1, and 4 are having poor performance on this client
running Lustre 2.12.5:
# lctl get_param osc.*.cur_grant_bytes
osc.lustre10-OST0000-osc-ffff8e47dc02a800.cur_grant_bytes=802542
osc.lustre10-OST0001-osc-ffff8e47dc02a800.cur_grant_bytes=924204
osc.lustre10-OST0002-osc-ffff8e47dc02a800.cur_grant_bytes=11076653
osc.lustre10-OST0003-osc-ffff8e47dc02a800.cur_grant_bytes=108098653
osc.lustre10-OST0004-osc-ffff8e47dc02a800.cur_grant_bytes=797559
osc.lustre10-OST0005-osc-ffff8e47dc02a800.cur_grant_bytes=4719258
osc.lustre10-OST0006-osc-ffff8e47dc02a800.cur_grant_bytes=4898757
osc.lustre10-OST0007-osc-ffff8e47dc02a800.cur_grant_bytes=10747719
osc.lustre10-OST0008-osc-ffff8e47dc02a800.cur_grant_bytes=315019599
osc.lustre10-OST0009-osc-ffff8e47dc02a800.cur_grant_bytes=597198336
osc.lustre10-OST000a-osc-ffff8e47dc02a800.cur_grant_bytes=278803109
osc.lustre10-OST000b-osc-ffff8e47dc02a800.cur_grant_bytes=1335800831
osc.lustre10-OST000c-osc-ffff8e47dc02a800.cur_grant_bytes=795705344
osc.lustre10-OST000d-osc-ffff8e47dc02a800.cur_grant_bytes=1335052800
osc.lustre10-OST000e-osc-ffff8e47dc02a800.cur_grant_bytes=474925228
osc.lustre10-OST000f-osc-ffff8e47dc02a800.cur_grant_bytes=1424795647

>From the previous discussion, the recommendation seems to have been to run
lctl set_param -P osc.*.grant_shrink=0 on the client.  Are there any
downsides to doing this?
Should I just blindly do this on all of my Lustre clients?

A little more insight into what's going on here would be appreciated.

Thanks,
Kevin

--
Kevin Hildebrand
University of Maryland
Division of IT
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.lustre.org/pipermail/lustre-discuss-lustre.org/attachments/20201208/59c9949a/attachment.html>


More information about the lustre-discuss mailing list