Re: [dpdk-dev] [PATCH v2 2/2] test/compress: im buffer too small - add unit tests

[Bruce Richardson <bruce.richardson@intel.com>]

On Thu, Apr 16, 2020 at 11:26:46AM +0000, Trahe, Fiona wrote:
> 
> 
> > -----Original Message-----
> > From: Akhil Goyal <akhil.goyal@nxp.com>
> > Sent: Thursday, April 16, 2020 11:25 AM
> > To: Trahe, Fiona <fiona.trahe@intel.com>; Dybkowski, AdamX <adamx.dybkowski@intel.com>;
> > dev@dpdk.org
> > Cc: Shally Verma <shallyv@marvell.com>
> > Subject: RE: [PATCH v2 2/2] test/compress: im buffer too small - add unit tests
> > 
> > Hi Fiona,
> > >
> > > Hi Akhil,
> > >
> > > >
> > > > Hi Fiona/Adam,
> > > >
> > > > > This patch adds a new test suite for verification of the "internal
> > > > > QAT IM buffer too small" case handling. These unit tests are
> > > > > specific to the QAT PMD only - that's why they are contained in
> > > > > a separate test suite.
> > > > >
> > > > > Signed-off-by: Adam Dybkowski <adamx.dybkowski@intel.com>
> > > > > ---
> > > >
> > > > Why do we need to have separate testsuite for QAT?
> > > > Can't we have a single one and based on capability of the driver,
> > > > Determine which tests need to be skipped in case they are not supported.
> > > > This would create a mess in the longer run just like cryptodev.
> > > >
> > > > Please fix this, we cannot take this patch as is.
> > >
> > > [Fiona] Yes, I understand your concern and we considered including in the main
> > > suite.
> > > However these tests are not based on something that can be
> > > checked in capabilities. They are tests to hone in on a specific corner case
> > > based on a QAT limitation in its intermediate buffer size. So some of the
> > > tests are to validate that the recent changes we made in the PMD correctly
> > > work around that limitation, but other tests are negative and expected to fail
> > > as provoking a corner-case that still exists. Other devices would probably not fail
> > > the same tests.
> > 
> > Does that mean that all PMDs will pass with the newly added testcase which is for
> > A corner case in QAT. If that is the case what is the issue in adding that in the main
> > Test suite. It will get passed in all PMDs, isn't it? Am I missing something?
> > 
> > I believe we should not have PMD specific test suites, rather it should be based on
> > Capabilities to identify the cases which should be run for that particular PMD.
> [Fiona] yes, several of the cases should pass on all PMDs.
> So we could move those into the main suite.
> But what to do about the negative tests? 
> Example: If a very large data buffer is passed to QAT to compress with dyn compression, it will get
> split in the PMD into many smaller requests to the hardware. However if the number 
> of requests is bigger than can fit on the qp then this will never succeed. The test
> validates that the PMD behaves appropriately in this expected error case. That same
> case would probably not have an error on another device. Maybe we should just leave out
> such negative tests, but I find them useful as they validate the known behaviour.
> The buffer size used in the test is based on the known size QAT can handle and the 
> corner case in which QAT will return an error.
> 
> I see 4 options to handle this:
> 1. Leave out those tests
> 2. Use a qat-specific test suite only for negative cases which are constructed based on specific qat internal meta-data.
> 3. Include the negative tests in the main suite, but only run them on QAT (by checking driver type)
> 4. include the negative tests in the main suite, run them on all, expecting a FAIL from QAT and a PASS from other devices.
> 
> My preference is for 2.
> But up to you.
> 
While not something for this release, perhaps in future cryptodev could
implement a "selftest()" callback API like rawdev does [1], which allows
drivers to implement their own specific test cases too.

[1] http://doc.dpdk.org/api-20.02/rte__rawdev_8h.html#a776edaa7060fc6a9d66e00f84132e140