[LU-10278] lfs migrate: make use of direct i/o optional Created: 24/Nov/17 Updated: 02/Jan/19 Resolved: 22/Feb/18 |
|
| Status: | Resolved |
| Project: | Lustre |
| Component/s: | None |
| Affects Version/s: | None |
| Fix Version/s: | Lustre 2.11.0 |
| Type: | Improvement | Priority: | Minor |
| Reporter: | Daniel Kobras (Inactive) | Assignee: | Emoly Liu |
| Resolution: | Fixed | Votes: | 0 |
| Labels: | patch | ||
| Issue Links: |
|
||||||||||||
| Rank (Obsolete): | 9223372036854775807 | ||||||||||||
| Description |
|
In order to avoid cache thrashing, lfs migrate currently uses direct i/o to copy file contents, which may leads to significantly different performance compared to normal (non-O_DIRECT) i/o, cf. for example the discussion at http://lists.lustre.org/pipermail/lustre-discuss-lustre.org/2017-November/015112.html. Internally, we've measured even more extreme differences where O_DIRECT throughput performed at 1/10th the normal rate. Therefore, I'd suggest to leave the choice between normal and direct i/o to the caller of lfs migrate by adding a new option |
| Comments |
| Comment by Jinshan Xiong (Inactive) [ 24/Nov/17 ] |
|
Then the correct direction to go is to use AIO+DirectIO. Please take a look at |
| Comment by Andreas Dilger [ 26/Nov/17 ] |
|
I think it is reasonable to have a simple change like this, since the fix to AIO in the kernel is fairly complex (and late for 2.11). The patch to lfs migrate should be simple enough that it can be backported to 2.10.x as well. I'm not against making AIO and copyfile() work well, but it shouldn't be an obstacle for a small fix in the meantime. |
| Comment by Gerrit Updater [ 28/Nov/17 ] |
|
Daniel Kobras (d.kobras@science-computing.de) uploaded a new patch: https://review.whamcloud.com/30301 |
| Comment by Peter Jones [ 15/Jan/18 ] |
|
kobras will you be able to refresh the patch as required? |
| Comment by Peter Jones [ 06/Feb/18 ] |
|
Emoly It seems that kobras is not available to refresh his patch. Could you please assist with this so that we can include this change in 2.11? Thanks Peter |
| Comment by Gerrit Updater [ 22/Feb/18 ] |
|
Oleg Drokin (oleg.drokin@intel.com) merged in patch https://review.whamcloud.com/30301/ |
| Comment by Peter Jones [ 22/Feb/18 ] |
|
Landed for 2.11 |