Re: [PULL 11/14] tests/tcg: reduce the number of plugin tests combinations

[Gustavo Romero <gustavo.romero@linaro.org>]

Hi,

On 7/28/25 17:14, Gustavo Romero wrote:
> Hi,
> 
> On 7/28/25 16:03, Pierrick Bouvier wrote:
>> Hi Alex,
>>
>> On 7/27/25 1:32 AM, Alex Bennée wrote:
>>> As our set of multiarch tests has grown the practice of running every
>>> plugin with every test is becoming unsustainable. If we switch to
>>> ensuring every test gets run with at least one plugin we can speed
>>> things up.
>>>
>>> Some plugins do need to be run with specific tests (for example the
>>> memory instrumentation test). We can handle this by manually adding
>>> them to EXTRA_RUNS. We also need to wrap rules in a CONFIG_PLUGIN test
>>> so we don't enable the runs when plugins are not enabled.
>>>
>>> Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
>>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>>> Message-ID: <20250725154517.3523095-12-alex.bennee@linaro.org>
>>>
>>> diff --git a/tests/tcg/Makefile.target b/tests/tcg/Makefile.target
>>> index a12b15637ea..18afd5be194 100644
>>> --- a/tests/tcg/Makefile.target
>>> +++ b/tests/tcg/Makefile.target
>>> @@ -173,14 +173,25 @@ PLUGINS=$(filter-out $(DISABLE_PLUGINS), \
>>>   # We need to ensure expand the run-plugin-TEST-with-PLUGIN
>>>   # pre-requistes manually here as we can't use stems to handle it. We
>>>   # only expand MULTIARCH_TESTS which are common on most of our targets
>>> -# to avoid an exponential explosion as new tests are added. We also
>>> -# add some special helpers the run-plugin- rules can use below.
>>> +# and rotate the plugins so we don't grow too out of control as new
>>> +# tests are added. Plugins that need to run with a specific test
>>> +# should ensure they add their combination to EXTRA_RUNS.
>>>   ifneq ($(MULTIARCH_TESTS),)
>>> -$(foreach p,$(PLUGINS), \
>>> -    $(foreach t,$(MULTIARCH_TESTS),\
>>> -        $(eval run-plugin-$(t)-with-$(p): $t $p) \
>>> -        $(eval RUN_TESTS+=run-plugin-$(t)-with-$(p))))
>>> +
>>> +NUM_PLUGINS := $(words $(PLUGINS))
>>> +NUM_TESTS := $(words $(MULTIARCH_TESTS))
>>> +
>>> +define mod_plus_one
>>> +  $(shell $(PYTHON) -c "print( ($(1) % $(2)) + 1 )")
>>> +endef
>>> +
>>> +$(foreach _idx, $(shell seq 1 $(NUM_TESTS)), \
>>> +    $(eval _test := $(word $(_idx), $(MULTIARCH_TESTS))) \
>>> +    $(eval _plugin := $(word $(call mod_plus_one, $(_idx), $(NUM_PLUGINS)), $(PLUGINS))) \
>>> +    $(eval run-plugin-$(_test)-with-$(_plugin): $(_test) $(_plugin)) \
>>> +    $(eval RUN_TESTS+=run-plugin-$(_test)-with-$(_plugin)))
>>> +
>>>   endif # MULTIARCH_TESTS
>>>   endif # CONFIG_PLUGIN
>>> diff --git a/tests/tcg/multiarch/Makefile.target b/tests/tcg/multiarch/Makefile.target
>>> index bfdf7197a7b..38345ff8805 100644
>>> --- a/tests/tcg/multiarch/Makefile.target
>>> +++ b/tests/tcg/multiarch/Makefile.target
>>> @@ -189,6 +189,10 @@ run-plugin-semiconsole-with-%:
>>>   TESTS += semihosting semiconsole
>>>   endif
>>> +test-plugin-mem-access: CFLAGS+=-pthread -O0
>>> +test-plugin-mem-access: LDFLAGS+=-pthread -O0
>>> +
>>> +ifeq ($(CONFIG_PLUGIN),y)
>>>   # Test plugin memory access instrumentation
>>>   run-plugin-test-plugin-mem-access-with-libmem.so: \
>>>       PLUGIN_ARGS=$(COMMA)print-accesses=true
>>> @@ -197,8 +201,8 @@ run-plugin-test-plugin-mem-access-with-libmem.so: \
>>>       $(SRC_PATH)/tests/tcg/multiarch/check-plugin-output.sh \
>>>       $(QEMU) $<
>>> -test-plugin-mem-access: CFLAGS+=-pthread -O0
>>> -test-plugin-mem-access: LDFLAGS+=-pthread -O0
>>> +EXTRA_RUNS += run-plugin-test-plugin-mem-access-with-libmem.so
>>> +endif
>>>   # Update TESTS
>>>   TESTS += $(MULTIARCH_TESTS)
>>> diff --git a/tests/tcg/multiarch/system/Makefile.softmmu-target b/tests/tcg/multiarch/system/Makefile.softmmu-target
>>> index 5acf2700812..4171b4e6aa0 100644
>>> --- a/tests/tcg/multiarch/system/Makefile.softmmu-target
>>> +++ b/tests/tcg/multiarch/system/Makefile.softmmu-target
>>> @@ -71,8 +71,11 @@ endif
>>>   MULTIARCH_RUNS += run-gdbstub-memory run-gdbstub-interrupt \
>>>       run-gdbstub-untimely-packet run-gdbstub-registers
>>> +ifeq ($(CONFIG_PLUGIN),y)
>>>   # Test plugin memory access instrumentation
>>> -run-plugin-memory-with-libmem.so:         \
>>> -    PLUGIN_ARGS=$(COMMA)region-summary=true
>>> -run-plugin-memory-with-libmem.so:         \
>>> -    CHECK_PLUGIN_OUTPUT_COMMAND=$(MULTIARCH_SYSTEM_SRC)/validate-memory-counts.py $@.out
>>> +run-plugin-memory-with-libmem.so: memory libmem.so
>>> +run-plugin-memory-with-libmem.so: PLUGIN_ARGS=$(COMMA)region-summary=true
>>> +run-plugin-memory-with-libmem.so: CHECK_PLUGIN_OUTPUT_COMMAND=$(MULTIARCH_SYSTEM_SRC)/validate-memory-counts.py $@.out
>>> +
>>> +EXTRA_RUNS += run-plugin-memory-with-libmem.so
>>> +endif
>>
>> I'm not sure how it's related, but check-tcg on aarch64 host now fails [1] since this series was merged, and I suspect it may be related to this patch. I didn't spend time to reproduce and investigate it.
>>
>> [1] https://github.com/pbo-linaro/qemu-ci/actions/runs/16575679153/job/46879690693
> 
> I was not able to reproduce it locally on 22.04, but in the CI indeed the test command is missing the "test-plugin-mem-access" binary at the end, just before redirection to .so.out, it should be:
> 
> [...] -D test-plugin-mem-access-with-libmem.so.pout test-plugin-mem-access >  run-plugin-test-plugin-mem-access-with-libmem.so.out
> 
> not:
> 
> [...] -D test-plugin-mem-access-with-libmem.so.pout  >  run-plugin-test-plugin-mem-access-with-libmem.so.out

The problem is that the new rules generated by a shuffled combination of tests and plugin
(the one using eval) sometimes does not include the rule for the test+plugin combination
passed via EXTRA_RUNs.

So EXTRA_RUNS tests like run-plugin-test-plugin-mem-access-with-libmem.so might end up
with a proper rule if the test test-plugin-mem-access is combined with other plugin
randomly, since now a plugin is picked up based on a tests index _idx modulo with the
number of plugins.

A possible fix is to generate correctly the rules for the tests with plugins passed
via EXTRA_RUNS and ideally, following the patch's mood, remove the test from running
if any other plugin (no shuffle with any other plugin).

Of course, as Pierrick said, this patch could be a premature optimization. So maybe
it doesn´t justify adding more complexity to our Makefile (Makefiles are hard to debug,
with 'eval' tricks, it's _reallly_ hard, so the more we avoid it the better).

That said, if we want to keep this commit, I've kicked off a test to fix it here:

https://gitlab.com/gusbromero/qemu/-/pipelines/1959953122

and sent the fix to the ML too. HTH.


Cheers,
Gustavo