Re: [dpdk-dev] [PATCH 3/3] acl: adjust the tests

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

On Wed, Apr 10, 2019 at 09:10:25AM -0400, Aaron Conole wrote:
> "Ananyev, Konstantin" <konstantin.ananyev@intel.com> writes:
> 
> >> 
> >> > > Hi Aaron,
> >> > >
> >> > >>
> >> > >> This makes the tests pass, and also ensures that on platforms where the
> >> > >> testing is supported, we can properly test the implementation specific
> >> > >> code.  One edge case is when we run on x86_64 systems that don't support
> >> > >> AVX2, but where the compiler can generate such instructions.  That could
> >> > >> be an enhancement in the future, but for now at least the tests will
> >> > >> pass.
> >> > >>
> >> > >> Signed-off-by: Aaron Conole <aconole@redhat.com>
> >> > >> ---
> >> > >>  app/test/test_acl.c             | 62 +++++++++++++--------------------
> >> > >>  lib/librte_acl/Makefile         |  1 +
> >> > >>  lib/librte_acl/acl_run_notsup.c | 46 ++++++++++++++++++++++++
> >> > >>  lib/librte_acl/meson.build      |  4 +--
> >> > >>  4 files changed, 73 insertions(+), 40 deletions(-)
> >> > >>  create mode 100644 lib/librte_acl/acl_run_notsup.c
> >> > >>
> >> > >> diff --git a/app/test/test_acl.c b/app/test/test_acl.c
> >> > >> index b1f75d1bc..c44faa251 100644
> >> > >> --- a/app/test/test_acl.c
> >> > >> +++ b/app/test/test_acl.c
> >> > >> @@ -408,6 +408,9 @@ test_classify(void)
> >> > >>  		return -1;
> >> > >>  	}
> >> > >>
> >> > >> +	/* Always use the scalar testing for now. */
> >> > >> +	rte_acl_set_ctx_classify(acx, RTE_ACL_CLASSIFY_SCALAR);
> >> > >> +
> >> > >>  	ret = 0;
> >> > >>  	for (i = 0; i != TEST_CLASSIFY_ITER; i++) {
> >> > >>
> >> > >> @@ -547,6 +550,7 @@ test_build_ports_range(void)
> >> > >>  	for (i = 0; i != RTE_DIM(test_data); i++)
> >> > >>  		data[i] = (uint8_t *)&test_data[i];
> >> > >>
> >> > >> +	rte_acl_set_ctx_classify(acx, RTE_ACL_CLASSIFY_SCALAR);
> >> > >>  	for (i = 0; i != RTE_DIM(test_rules); i++) {
> >> > >>  		rte_acl_reset(acx);
> >> > >>  		ret = test_classify_buid(acx, test_rules, i + 1);
> >> > >> @@ -911,6 +915,8 @@ test_convert_rules(const char *desc,
> >> > >>  		return -1;
> >> > >>  	}
> >> > >>
> >> > >> +	rte_acl_set_ctx_classify(acx, RTE_ACL_CLASSIFY_SCALAR);
> >> > >> +
> >> > >
> >> > > As I understand here and above, on x86 you replaced default algo (SSE, AVX2)
> >> > > with scalar one, right?
> >> > > That looks like reduction of test coverage for x86.
> >> >
> >> > In one way, you're right.  However, the tests weren't testing what they
> >> > purported anyway.
> >> 
> >> Could you explain a bit more here?
> >> What I am seeing: tests were running bot sse(or avx2) and scalar classify() method.
> >> Now they always running scalar only.
> >> To me it definitely looks like reduction in coverage.
> >> 
> >> >  Actually, it's just a shift I think (previously, it
> >> > would have tested the AVX2 but I don't see AVX2 having a fallback into
> >> > the SSE code - unlike the SSE code falling back into scalar).
> >> 
> >> Not sure I understand you here.
> >> What fallback for AVX2 you expect that you think is missing?
> >> 
> >> >
> >> > The tests were failing for a number of reasons when built with meson,
> >> 
> >> Ok, but with legacy build system (make) on x86 all tests passes, right?
> >> So the problem is in new build system, not in the test itself.
> >> Why we should compromise our test coverage to make it work with
> >> new tools?
> >> That just hides the problem without fixing it.
> >> Instead I think the build system needs to be fixed.
> >> Looking at it a bit closely, for .so meson+ninja generates code with
> >> correct version of the function:
> >> 
> >> nm x86_64-native-linuxapp-gcc-meson/lib/librte_acl.so.2 | grep acl_classify_sse
> >> 000000000000fa50 t rte_acl_classify_sse
> >> 
> >> So for 'meson -Ddefault_library=shared'
> >> acl_autotest passes without the problem.
> >> 
> >> Though for static lib we have both:
> >> nm x86_64-native-linuxapp-gcc-meson/lib/librte_acl.a | grep acl_classify_sse
> >> 0000000000000000 W rte_acl_classify_sse
> >> 0000000000004880 T rte_acl_classify_sse
> >> 
> >> And then linker pickups the wrong one:
> >> nm x86_64-native-linuxapp-gcc-meson/app/test/dpdk-test | grep acl_classify_sse
> >> 00000000005f6100 W rte_acl_classify_sse
> >> 
> >> While for make:
> >> $ nm x86_64-native-linuxapp-gcc-aesmb/lib/librte_acl.a | grep acl_classify_sse
> >> 0000000000000000 W rte_acl_classify_sse
> >> 0000000000004880 T rte_acl_classify_sse
> >> $ nm x86_64-native-linuxapp-gcc-aesmb/app/test | grep acl_classify_sse
> >> 0000000000240440 T rte_acl_classify_sse
> >> 
> >> Linker pickups the right one.
> >
> > And the changes below make linker to pick-up the proper version of the function
> > and make acl_autotest to pass for static build too.
> >
> > diff --git a/app/test/meson.build b/app/test/meson.build
> > index 867cc5863..4364be932 100644
> > --- a/app/test/meson.build
> > +++ b/app/test/meson.build
> > @@ -328,6 +328,7 @@ test_dep_objs += cc.find_library('execinfo', required: false)
> >  link_libs = []
> >  if get_option('default_library') == 'static'
> >         link_libs = dpdk_drivers
> > +       link_libs += dpdk_static_libraries
> >  endif
> >
> >  if get_option('tests')
> > diff --git a/meson.build b/meson.build
> > index a96486597..df1e1c41c 100644
> > --- a/meson.build
> > +++ b/meson.build
> > @@ -62,6 +62,7 @@ configure_file(output: build_cfg,
> >  # for static builds, include the drivers as libs and we need to "whole-archive"
> >  # them.
> >  dpdk_drivers = ['-Wl,--whole-archive'] + dpdk_drivers + ['-Wl,--no-whole-archive']
> > +dpdk_static_libraries = ['-Wl,--whole-archive'] + dpdk_static_libraries + ['-Wl,--no-whole-archive']
> >
> > Not saying that's the proper patch, but just to prove that linking librte_acl.a
> > with '--whole-archive' does fix the problem.
> > Bruce, could you point is the best way to fix things here
> > (my meson knowledge is very limited)?
> > Do we need extra container here as 'whole_archive_static_libraries[]' or so?
> > Thanks
> > Konstantin
> 
> Okay - I'll look at this part more.  I think I went down the path of
> explicitly setting these because the comments didn't match with what was
> occuring (for example, in the section that I changed that loops through
> all versions, only the AVX2 and Scalar were being tested on my system,
> while the comment implied SSE).
> 
> I also believe that I split out the functions because of the linking
> issue (I guess the way the linker resolves the functions works properly
> when the weak versions are in a different translation unit)?  I'll spend
> some time trying to get it working in a different way.
> 
> Regardless, this wasn't ready for posting as 'PATCH' - I meant it as
> RFC.  I don't intend to change the first two patches, though.
> 
> And thank you for the all the feedback!
> 
I've dug into this a bit, and I'm doing up a patch to remove the use of
weak symbols in our libraries (note, just libs, not drivers) entirely.
That's fairly easy to do, and not a big change, but should make this
problem go away.

/Bruce