Re: [PATCH blktests v2 0/3] Test different queue counts

[Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>]

On Mar 27, 2023 / 17:41, Daniel Wagner wrote:
> On Thu, Mar 23, 2023 at 11:06:53AM +0000, Shinichiro Kawasaki wrote:
> > On Mar 22, 2023 / 11:16, Daniel Wagner wrote:
> > > Setup different queues, e.g. read and poll queues.
> > > 
> > > There is still the problem that _require_nvme_trtype_is_fabrics also includes
> > > the loop transport which has no support for different queue types.
> > > 
> > > See also https://lore.kernel.org/linux-nvme/20230322002350.4038048-1-kbusch@meta.com/
> > 
> > Hi Daniel, thanks for the patches. The new test case catches some bugs. Looks
> > valuable.
> > 
> > I ran the test case using various nvme_trtype on kernel v6.2 and v6.3-rc3, and
> > observed hangs. I applied the 3rd patch in the link above on top of v6.3-rc3 and
> > confirmed the hang disappears. I would like to wait for the kernel fix patch
> > delivered to upstream, before adding this test case to blktests master.
> 
> Okay makes sense.
> 
> > When I ran the test case without setting nvme_trtype, kernel reported messages
> > below:
> > 
> > [  199.621431][ T1001] nvme_fabrics: invalid parameter 'nr_write_queues=%d'
> > [  201.271200][ T1030] nvme_fabrics: invalid parameter 'nr_write_queues=%d'
> > [  201.272155][ T1030] nvme_fabrics: invalid parameter 'nr_poll_queues=%d'
> 
> BTW, I've added a '|| echo FAIL' to catch those.
> 
> > Is it useful to run the test case with default nvme_trtype=loop?
> 
> No, we should run this test only for those transport which actually support the
> different queue types. Christoph suggest to figure out before running the test
> if it is actually supported. So my first idea was to check what options are
> supported by reading /dev/nvme-fabrics. But this will return all options we are
> parsed by fabrics.c but not the subset which each transport might only support.
> 
> So to figure this out we would need to do a full setup just to figure out if it
> is supported. I think the currently best approach would just to limit this test
> to tcp and rdma. Maybe we could add something like
> 
> rc:
> _require_nvme_trtype() {
> 	local trtype
> 	for trtype in "$@"; do
> 		if [[ "${nvme_trtype}" == "$trtype" ]]; then
> 			return 0
> 		fi
> 	done
> 	SKIP_REASONS+=("nvme_trtype=${nvme_trtype} is not supported in this test")
> 	return 1
> }
> 
> 047:
> requires() {
> 	_nvme_requires
> 	_have_xfs
> 	_have_fio
> 	_require_nvme_trtype tcp rdma
> 	_have_kver 4 21
> }
> 
> What do you think?

Thanks for the clarifications about the requirements. I think your approach will
work. Having said that, we may have another potentially simpler solution:

- Do not check _require_nvme_trtype and _have_kver in requires().
- After setting nr_write_queues in test(), check if dmesg contains the error
  "invalid parameter 'nr_write_queues" using the helper function
  _dmesg_since_test_start().
- If the error is reported, set SKIP_REASONS and return from test().
  Blktests will report the test case as "not run".

This approach assumes that the "invalid parameter" is printed when the test case
should be skipped (loop transport, older kernel version).

As a generic guide, SKIP_REASONS should be set in requires() before test().
However, if the SKIP_REASONS can not be checked before test(), blktests allows
to set it in test(). The test case block/030 is such an exception. I think your
new test case can be another exception. With this, we do not need to repeat the
full setup. And it might be more robust against future changes such as new
transport types.

Thoughts?

-- 
Shin'ichiro Kawasaki