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

[Aaron Conole <aconole@redhat.com>]

"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!

>
>> 
>> 
>> > and on the systems I tested with (including tests under travis).
>> >
>> > 1. Any meson build that I observed didn't correctly fill anything but
>> >    the scalar variable.  I had to remove the -ENOTSUP definitions in the
>> >    rte_acl.c file (forgot to git add it), and make the second version.
>> >
>> > 2. The tests never selected scalar, or nor sse implementations.
>> 
>> As I can see test_classify_run() *always* run both default method (sse/avx2 on x86)
>> and then scalar one.
>> 
>> >  Rather,
>> >    they selected only what the currently running platform provided.
>> >    This meant that I was always seeing the AVX2 code executed, but never
>> >    SSE nor scalar (but for one case) - at least as far as I could see.
>> >
>> > There were others - I iterated on these for a few days.
>> >
>> > This is why I changed a block to run through each implementation in one
>> > of the versions.
>> >
>> > HOWEVER, it's still deficient.
>> >
>> > We need to fully cover all the cases.  BUT it's better than the failure
>> > that currently happens on almost every system I've tried - including
>> > shipping the build to travis to run.  So, I figured running > failing with
>> > almost no reason why.  And looking into the failure revealed that the
>> > meson build didn't even include the platform specific builds.
>> >
>> > During my rework, I can change the test cases to iterate as in other
>> > test cases.  It will extend the time.  And I don't know how to resolve
>> > the case where we run on a system that doesn't support AVX2 but we have
>> > a compiler that supports AVX2 (since that case will fail - but we
>> > shouldn't even attempt it).
>> 
>> I don't see why that should happen.
>> At rte_acl_init() we do check does that machine supports AVX2(SSE, NEON)
>> instructions or not.
>> Are you saying under some circumstances rte_acl_init() are not working properly,
>> or not get invoked?
>> 
>> Konstantin