SPDK needs a delay between creating an I/O queue pair and sending I/O commands in Virtualbox => fixed in SVN/next maintenance

[crane]

We are testing SPDK in Fedora25 in Virtualbox, and find its hello_world demo would hang after repeating several times. SPDK team found the workaround way in SPDK, and commit here:  https://github.com/spdk/spdk/commit/13f8cf1536ca5222878d2c03802fb367e1340ef9

It gives a 100us delay to Virtualbox after allocating an I/O queue pair. However, on another platform, we found the delay should be enlarged to 1000us to make SPDK hello_world test pass.

Here is the hello_world's procedure:

1. admin cmd1: create one IO CQ
2. wait until cmd1 completion
3. admin cmd2: create one IO SQ
4. wait until cmd2 completion
5. delay 100us (or 1000us in my platform, but hope it could be eliminated)
6. IO cmd3: write data
7. wait until cmd3 completion <===== HANG here
8. ...

Does Virtualbox NVMe device sends CQ too early?

[aeichner]

Thanks for the report! Will be fixed in the next maintenance release.

[frank]

Fixed in 5.1.26.

[crane]

tested and verified in 5.1.26