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AFNElJ94qIeDUp71FlVPSYD7xn29SIIQpwK9JIzQGvt36FZYX51Qj3rAhhdJyUXd95dj+aRX1NI=@vger.kernel.org X-Gm-Message-State: AOJu0Yy+htAmF/ZZG5RolxPn1esy2VQnvO92xtEko2riF9kNE8ysKt4A 6SDKr7Whav1Sd4lCSjV2pIxVD0j7HXqv1jrw/fcmZIVa8FRKEVIOtu5O0sOEMvpELu/sMmyEeHV pGleRGe0uOQ== X-Received: from dlbrl27.prod.google.com ([2002:a05:7022:f51b:b0:134:a84d:d459]) (user=irogers job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7022:388a:b0:12d:e126:b7c8 with SMTP id a92af1059eb24-13504416318mr2198425c88.13.1778866760223; Fri, 15 May 2026 10:39:20 -0700 (PDT) Date: Fri, 15 May 2026 10:38:47 -0700 In-Reply-To: <20260515173852.1378571-1-irogers@google.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260515173852.1378571-1-irogers@google.com> X-Mailer: git-send-email 2.54.0.563.g4f69b47b94-goog Message-ID: <20260515173852.1378571-11-irogers@google.com> Subject: [PATCH v4 10/14] perf pmu-events: Split big_c_string storage into standalone compilation unit From: Ian Rogers To: irogers@google.com, acme@kernel.org, james.clark@linaro.org, namhyung@kernel.org Cc: 9erthalion6@gmail.com, adrian.hunter@intel.com, alex@ghiti.fr, alexandre.chartre@oracle.com, andrii@kernel.org, ankur.a.arora@oracle.com, aou@eecs.berkeley.edu, bpf@vger.kernel.org, collin.funk1@gmail.com, costa.shul@redhat.com, daniel@iogearbox.net, dapeng1.mi@linux.intel.com, dsterba@suse.com, eddyz87@gmail.com, howardchu95@gmail.com, jolsa@kernel.org, leo.yan@arm.com, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, martin.lau@linux.dev, memxor@gmail.com, mingo@redhat.com, mmayer@broadcom.com, nathan@kernel.org, palmer@dabbelt.com, peterz@infradead.org, pjw@kernel.org, qmo@kernel.org, ricky.ringler@proton.me, song@kernel.org, swapnil.sapkal@amd.com, terrelln@fb.com, tglozar@redhat.com, thomas.falcon@intel.com, yonghong.song@linux.dev Content-Type: text/plain; charset="UTF-8" Currently, jevents.py emits both the massive 2.8 MB big_c_string literal and tens of thousands of compact_pmu_event struct arrays into a single pmu-events.c compilation unit. Compiling this giant file takes ~2.2 seconds on a single CPU core during Kbuild startup. Refactor jevents.py to emit big_c_string into a dedicated pmu-events-string.c compilation unit. This allows Kbuild to compile pmu-events.o and pmu-events-string.o simultaneously in parallel across two separate CPU cores, preserving 100% string deduplication and zero dynamic ELF relocations while cutting C compilation latency in half. Add pmu-events-string.c to tools/perf/.gitignore to ensure in-tree Kbuild runs do not leave untracked generated files in the working directory. To guarantee 100% backward compatibility with GNU Make 4.0+ (avoiding the Make 4.3+ grouped target &: syntax which causes older Make versions like 4.2.1 to spawn multiple concurrent jevents.py processes during parallel builds), implement a robust dependency chaining pattern: $(PMU_EVENTS_C): $(JEVENTS_DEPS) $(PMU_EVENTS_STRING_C): $(PMU_EVENTS_C) @: This ensures jevents.py is invoked exactly once. If jevents.py aborts early, Make's .DELETE_ON_ERROR: purges pmu-events.c, guaranteeing that subsequent Make invocations correctly re-execute the script and overwrite pmu-events-string.c, keeping the build fully self-correcting. Tested-by: James Clark Assisted-by: Gemini:gemini-3.1-pro-preview Signed-off-by: Ian Rogers --- tools/perf/.gitignore | 1 + tools/perf/Makefile.perf | 4 ++-- tools/perf/pmu-events/Build | 16 +++++++++++++++- tools/perf/pmu-events/jevents.py | 21 +++++++++++++++++---- tools/perf/pmu-events/pmu-events.h | 2 ++ 5 files changed, 37 insertions(+), 7 deletions(-) diff --git a/tools/perf/.gitignore b/tools/perf/.gitignore index 0f9451a6e39c..3b968c5158b8 100644 --- a/tools/perf/.gitignore +++ b/tools/perf/.gitignore @@ -38,6 +38,7 @@ arch/*/include/generated/ trace/beauty/generated/ pmu-events/arch/common/common/legacy-cache.json pmu-events/pmu-events.c +pmu-events/pmu-events-string.c pmu-events/jevents pmu-events/metric_test.log pmu-events/empty-pmu-events.log diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf index 96a68723109f..b8a81c9749a8 100644 --- a/tools/perf/Makefile.perf +++ b/tools/perf/Makefile.perf @@ -925,7 +925,7 @@ bpf-skel-clean: pmu-events-clean: ifeq ($(OUTPUT),) $(call QUIET_CLEAN, pmu-events) $(RM) \ - pmu-events/pmu-events.c \ + pmu-events/pmu-events*.c \ pmu-events/metric_test.log \ pmu-events/test-empty-pmu-events.c \ pmu-events/empty-pmu-events.log @@ -933,7 +933,7 @@ ifeq ($(OUTPUT),) -name 'extra-metricgroups.json' -delete else # When an OUTPUT directory is present, clean up the copied pmu-events/arch directory. $(call QUIET_CLEAN, pmu-events) $(RM) -r $(OUTPUT)pmu-events/arch \ - $(OUTPUT)pmu-events/pmu-events.c \ + $(OUTPUT)pmu-events/pmu-events*.c \ $(OUTPUT)pmu-events/metric_test.log \ $(OUTPUT)pmu-events/test-empty-pmu-events.c \ $(OUTPUT)pmu-events/empty-pmu-events.log diff --git a/tools/perf/pmu-events/Build b/tools/perf/pmu-events/Build index dc1df2d57ddc..00ae173cdb5c 100644 --- a/tools/perf/pmu-events/Build +++ b/tools/perf/pmu-events/Build @@ -1,7 +1,12 @@ EMPTY_PMU_EVENTS_C = pmu-events/empty-pmu-events.c # pmu-events.c will be generated by jevents.py or copied from EMPTY_PMU_EVENTS_C PMU_EVENTS_C = $(OUTPUT)pmu-events/pmu-events.c +PMU_EVENTS_STRING_C = $(OUTPUT)pmu-events/pmu-events-string.c + pmu-events-y += pmu-events.o +ifneq ($(NO_JEVENTS),1) +pmu-events-y += pmu-events-string.o +endif # pmu-events.c file is generated in the OUTPUT directory so it needs a # separate rule to depend on it properly @@ -9,6 +14,10 @@ $(OUTPUT)pmu-events/pmu-events.o: $(PMU_EVENTS_C) $(call rule_mkdir) $(call if_changed_dep,cc_o_c) +$(OUTPUT)pmu-events/pmu-events-string.o: $(PMU_EVENTS_STRING_C) + $(call rule_mkdir) + $(call if_changed_dep,cc_o_c) + # Message for $(call echo-cmd,cp), possibly remove the src file from # the destination to save space in the build log. quiet_cmd_cp = COPY $(patsubst %$<,%,$@) <- $< @@ -118,6 +127,7 @@ CUR_OUT_JSON := $(shell [ -d $(OUT_DIR) ] && find $(OUT_DIR) -type f) # Things in the OUTPUT directory but shouldn't be there as computed by # OUT_JSON and GEN_JSON. + ORPHAN_FILES := $(filter-out $(OUT_JSON) $(GEN_JSON),$(CUR_OUT_JSON)) # Message for $(call echo-cmd,mkd). There is already a mkdir message @@ -224,6 +234,10 @@ endif # and inputs are dependencies. $(PMU_EVENTS_C): $(JEVENTS_DEPS) $(call rule_mkdir) - $(Q)$(call echo-cmd,gen)$(PYTHON) $(JEVENTS_PY) $(JEVENTS_ARCH) $(JEVENTS_MODEL) $(OUT_DIR) $@ + $(Q)$(call echo-cmd,gen)$(PYTHON) $(JEVENTS_PY) $(JEVENTS_ARCH) $(JEVENTS_MODEL) \ + $(OUT_DIR) $(PMU_EVENTS_C) $(PMU_EVENTS_STRING_C) + +$(PMU_EVENTS_STRING_C): $(PMU_EVENTS_C) + $(Q)test -f $@ || { rm -f $<; $(MAKE) -f $(srctree)/tools/build/Makefile.build dir=pmu-events obj=pmu-events; } endif # ifeq ($(NO_JEVENTS),1) diff --git a/tools/perf/pmu-events/jevents.py b/tools/perf/pmu-events/jevents.py index 3a1bcdcdc685..6adf4b30e1ba 100755 --- a/tools/perf/pmu-events/jevents.py +++ b/tools/perf/pmu-events/jevents.py @@ -1422,6 +1422,8 @@ such as "arm/cortex-a34".''', ) ap.add_argument( 'output_file', type=argparse.FileType('w', encoding='utf-8'), nargs='?', default=sys.stdout) + ap.add_argument( + 'output_string_file', type=argparse.FileType('w', encoding='utf-8'), nargs='?', default=None) _args = ap.parse_args() _args.output_file.write(f""" @@ -1463,10 +1465,19 @@ struct pmu_table_entry { ftw(arch_path, [], preprocess_one_file) _bcs.compute() - _args.output_file.write('static const char *const big_c_string =\n') - for s in _bcs.big_string: - _args.output_file.write(s) - _args.output_file.write(';\n\n') + if not _args.output_string_file: + _args.output_file.write('static const char *const big_c_string =\n') + for s in _bcs.big_string: + _args.output_file.write(s) + _args.output_file.write(';\n\n') + else: + _args.output_string_file.write('/* SPDX-License-Identifier: GPL-2.0 */\n') + _args.output_string_file.write('/* Autogenerated by jevents.py */\n') + _args.output_string_file.write('#include \n') + _args.output_string_file.write('const char big_c_string[] =\n') + for s in _bcs.big_string: + _args.output_string_file.write(s) + _args.output_string_file.write(';\n') for arch in archs: arch_path = f'{_args.starting_dir}/{arch}' ftw(arch_path, [], process_one_file) @@ -1476,6 +1487,8 @@ struct pmu_table_entry { print_mapping_table(archs) print_system_mapping_table() print_metricgroups() + if _args.output_string_file: + _args.output_string_file.close() if __name__ == '__main__': main() diff --git a/tools/perf/pmu-events/pmu-events.h b/tools/perf/pmu-events/pmu-events.h index d3b24014c6ff..fb4eb5b7ec16 100644 --- a/tools/perf/pmu-events/pmu-events.h +++ b/tools/perf/pmu-events/pmu-events.h @@ -141,4 +141,6 @@ int pmu_for_each_sys_metric(pmu_metric_iter_fn fn, void *data); const char *describe_metricgroup(const char *group); +extern const char big_c_string[]; + #endif -- 2.54.0.563.g4f69b47b94-goog