Messages in this thread | | | From | Ian Rogers <> | Date | Wed, 30 Aug 2023 10:59:48 -0700 | Subject | Re: [PATCH v6 4/6] perf jevents: Add a new expression builtin strcmp_cpuid_str() |
| |
On Wed, Aug 30, 2023 at 10:15 AM James Clark <james.clark@arm.com> wrote: > > > > On 30/08/2023 00:46, Ian Rogers wrote: > > On Wed, Aug 16, 2023 at 4:52 AM James Clark <james.clark@arm.com> wrote: > >> > >> This will allow writing formulas that are conditional on a specific > >> CPU type or CPU version. It calls through to the existing > >> strcmp_cpuid_str() function in Perf which has a default weak version, > >> and an arch specific version for x86 and arm64. > >> > >> The function takes an 'ID' type value, which is a string. But in this > >> case Arm CPU IDs are hex numbers prefixed with '0x'. metric.py > >> assumes strings are only used by event names, and that they can't start > >> with a number ('0'), so an additional change has to be made to the > >> regex to convert hex numbers back to 'ID' types. > >> > >> Signed-off-by: James Clark <james.clark@arm.com> > >> --- > >> tools/perf/arch/arm64/util/pmu.c | 18 +----------------- > >> tools/perf/pmu-events/metric.py | 17 +++++++++++++++-- > >> tools/perf/util/expr.c | 18 ++++++++++++++++++ > >> tools/perf/util/expr.h | 1 + > >> tools/perf/util/expr.l | 1 + > >> tools/perf/util/expr.y | 8 +++++++- > >> tools/perf/util/pmu.c | 17 +++++++++++++++++ > >> tools/perf/util/pmu.h | 1 + > >> 8 files changed, 61 insertions(+), 20 deletions(-) > >> > >> diff --git a/tools/perf/arch/arm64/util/pmu.c b/tools/perf/arch/arm64/util/pmu.c > >> index 512a8f13c4de..615084eb88d8 100644 > >> --- a/tools/perf/arch/arm64/util/pmu.c > >> +++ b/tools/perf/arch/arm64/util/pmu.c > >> @@ -2,28 +2,12 @@ > >> > >> #include <internal/cpumap.h> > >> #include "../../../util/cpumap.h" > >> +#include "../../../util/header.h" > >> #include "../../../util/pmu.h" > >> #include "../../../util/pmus.h" > >> #include <api/fs/fs.h> > >> #include <math.h> > >> > >> -static struct perf_pmu *pmu__find_core_pmu(void) > >> -{ > >> - struct perf_pmu *pmu = NULL; > >> - > >> - while ((pmu = perf_pmus__scan_core(pmu))) { > >> - /* > >> - * The cpumap should cover all CPUs. Otherwise, some CPUs may > >> - * not support some events or have different event IDs. > >> - */ > >> - if (RC_CHK_ACCESS(pmu->cpus)->nr != cpu__max_cpu().cpu) > >> - return NULL; > >> - > >> - return pmu; > >> - } > >> - return NULL; > >> -} > >> - > >> const struct pmu_metrics_table *pmu_metrics_table__find(void) > >> { > >> struct perf_pmu *pmu = pmu__find_core_pmu(); > >> diff --git a/tools/perf/pmu-events/metric.py b/tools/perf/pmu-events/metric.py > >> index 85a3545f5b6a..0e9ec65d92ae 100644 > >> --- a/tools/perf/pmu-events/metric.py > >> +++ b/tools/perf/pmu-events/metric.py > >> @@ -413,6 +413,10 @@ def has_event(event: Event) -> Function: > >> # pylint: disable=invalid-name > >> return Function('has_event', event) > >> > >> +def strcmp_cpuid_str(event: str) -> Function: > >> + # pylint: disable=redefined-builtin > >> + # pylint: disable=invalid-name > >> + return Function('strcmp_cpuid_str', event) > >> > >> class Metric: > >> """An individual metric that will specifiable on the perf command line.""" > >> @@ -541,14 +545,23 @@ def ParsePerfJson(orig: str) -> Expression: > >> """ > >> # pylint: disable=eval-used > >> py = orig.strip() > >> + # First try to convert everything that looks like a string (event name) into Event(r"EVENT_NAME"). > >> + # This isn't very selective so is followed up by converting some unwanted conversions back again > >> py = re.sub(r'([a-zA-Z][^-+/\* \\\(\),]*(?:\\.[^-+/\* \\\(\),]*)*)', > >> r'Event(r"\1")', py) > >> + # If it started with a # it should have been a literal, rather than an event name > >> py = re.sub(r'#Event\(r"([^"]*)"\)', r'Literal("#\1")', py) > >> + # Convert accidentally converted hex constants ("0Event(r"xDEADBEEF)"") back to a constant, > >> + # but keep it wrapped in Event(), otherwise Python drops the 0x prefix and it gets interpreted as > >> + # a double by the Bison parser > >> + py = re.sub(r'0Event\(r"[xX]([0-9a-fA-F]*)"\)', r'Event("0x\1")', py) > >> + # Convert accidentally converted scientific notation constants back > >> py = re.sub(r'([0-9]+)Event\(r"(e[0-9]+)"\)', r'\1\2', py) > >> - keywords = ['if', 'else', 'min', 'max', 'd_ratio', 'source_count', 'has_event'] > >> + # Convert all the known keywords back from events to just the keyword > >> + keywords = ['if', 'else', 'min', 'max', 'd_ratio', 'source_count', 'has_event', 'strcmp_cpuid_str', > >> + 'cpuid_not_more_than'] > >> for kw in keywords: > >> py = re.sub(rf'Event\(r"{kw}"\)', kw, py) > >> - > >> try: > >> parsed = ast.parse(py, mode='eval') > >> except SyntaxError as e: > >> diff --git a/tools/perf/util/expr.c b/tools/perf/util/expr.c > >> index 7410a165f68b..0985a3cbc6f9 100644 > >> --- a/tools/perf/util/expr.c > >> +++ b/tools/perf/util/expr.c > >> @@ -13,6 +13,8 @@ > >> #include <util/expr-bison.h> > >> #include <util/expr-flex.h> > >> #include "util/hashmap.h" > >> +#include "util/header.h" > >> +#include "util/pmu.h" > >> #include "smt.h" > >> #include "tsc.h" > >> #include <api/fs/fs.h> > >> @@ -495,3 +497,19 @@ double expr__has_event(const struct expr_parse_ctx *ctx, bool compute_ids, const > >> evlist__delete(tmp); > >> return ret; > >> } > >> + > >> +double expr__strcmp_cpuid_str(const struct expr_parse_ctx *ctx __maybe_unused, > >> + bool compute_ids __maybe_unused, const char *test_id) > >> +{ > >> + double ret; > >> + struct perf_pmu *pmu = pmu__find_core_pmu(); > >> + char *cpuid = perf_pmu__getcpuid(pmu); > >> + > >> + if (!cpuid) > >> + return NAN; > >> + > >> + ret = !strcmp_cpuid_str(test_id, cpuid); > >> + > >> + free(cpuid); > >> + return ret; > >> +} > >> diff --git a/tools/perf/util/expr.h b/tools/perf/util/expr.h > >> index 3c1e49b3e35d..c0cec29ddc29 100644 > >> --- a/tools/perf/util/expr.h > >> +++ b/tools/perf/util/expr.h > >> @@ -55,5 +55,6 @@ double expr_id_data__value(const struct expr_id_data *data); > >> double expr_id_data__source_count(const struct expr_id_data *data); > >> double expr__get_literal(const char *literal, const struct expr_scanner_ctx *ctx); > >> double expr__has_event(const struct expr_parse_ctx *ctx, bool compute_ids, const char *id); > >> +double expr__strcmp_cpuid_str(const struct expr_parse_ctx *ctx, bool compute_ids, const char *id); > >> > >> #endif > >> diff --git a/tools/perf/util/expr.l b/tools/perf/util/expr.l > >> index dbb117414710..0feef0726c48 100644 > >> --- a/tools/perf/util/expr.l > >> +++ b/tools/perf/util/expr.l > >> @@ -114,6 +114,7 @@ if { return IF; } > >> else { return ELSE; } > >> source_count { return SOURCE_COUNT; } > >> has_event { return HAS_EVENT; } > >> +strcmp_cpuid_str { return STRCMP_CPUID_STR; } > > > > For the sake of coverage, it'd be nice to have a test case like: > > https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/tests/expr.c?h=tmp.perf-tools-next#n257 > > > >> {literal} { return literal(yyscanner, sctx); } > >> {number} { return value(yyscanner); } > >> {symbol} { return str(yyscanner, ID, sctx->runtime); } > >> diff --git a/tools/perf/util/expr.y b/tools/perf/util/expr.y > >> index 65d54a6f29ad..6c93b358cc2d 100644 > >> --- a/tools/perf/util/expr.y > >> +++ b/tools/perf/util/expr.y > >> @@ -39,7 +39,7 @@ int expr_lex(YYSTYPE * yylval_param , void *yyscanner); > >> } ids; > >> } > >> > >> -%token ID NUMBER MIN MAX IF ELSE LITERAL D_RATIO SOURCE_COUNT HAS_EVENT EXPR_ERROR > >> +%token ID NUMBER MIN MAX IF ELSE LITERAL D_RATIO SOURCE_COUNT HAS_EVENT STRCMP_CPUID_STR EXPR_ERROR > >> %left MIN MAX IF > >> %left '|' > >> %left '^' > >> @@ -207,6 +207,12 @@ expr: NUMBER > >> $$.ids = NULL; > >> free($3); > >> } > >> +| STRCMP_CPUID_STR '(' ID ')' > >> +{ > >> + $$.val = expr__strcmp_cpuid_str(ctx, compute_ids, $3); > >> + $$.ids = NULL; > >> + free($3); > >> +} > >> | expr '|' expr > >> { > >> if (is_const($1.val) && is_const($3.val)) { > >> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c > >> index d5406effc169..a7f05e4dda97 100644 > >> --- a/tools/perf/util/pmu.c > >> +++ b/tools/perf/util/pmu.c > >> @@ -1790,3 +1790,20 @@ void perf_pmu__delete(struct perf_pmu *pmu) > >> zfree(&pmu->alias_name); > >> free(pmu); > >> } > >> + > >> +struct perf_pmu *pmu__find_core_pmu(void) > > > > I think as this is scanning all PMUs it more logically belongs in > > pmus.c than pmu.c. > > > >> +{ > >> + struct perf_pmu *pmu = NULL; > >> + > >> + while ((pmu = perf_pmus__scan_core(pmu))) { > >> + /* > >> + * The cpumap should cover all CPUs. Otherwise, some CPUs may > >> + * not support some events or have different event IDs. > >> + */ > >> + if (RC_CHK_ACCESS(pmu->cpus)->nr != cpu__max_cpu().cpu) > > > > The RC_CHK_ACCESS can be avoided using perf_cpu_map__nr. > > > > Not all CPUs need to be online. I think the number for the PMU is > > bound by the number online while cpu__max_cpu gives the maximum > > present. It is common to workaround SMT vulnerabilities by making > > cores offline in which case this would never be true. I think the > > following is nearly equivalent and simpler: > > > > perf_pmus__num_core_pmus > 1 ? NULL : perf_pmus__scan_core(NULL); > > > > I'm not sure about this one, I'm hesitant to change it because I only > moved it out of the arm file and into the generic one and it seems like > it could cause subtle issues. > > From the comment above the if statement, it seems like it intentionally > refuses to return a PMU on heterogeneous systems, and the original > commit message (e126bef55f1d) from John lines up with that too. I can't > see exactly why it should be like that though. > > Although you could say that now I've pulled some Arm specific quirk into > the generic code and we should re-think it. To me I don't see why it > doesn't just unconditionally return the first core PMU it finds on any > architecture, but I'd like to understand the original intention first. > > Apart from this one, I've done the other changes and will send patches.
Even on a homogeneous ARM system this will always return NULL/NAN if a core is taken offline. We didn't used to count core PMUs, so the approach I proposed wouldn't have been possible previously.
Thanks, Ian
> > Thanks, > > Ian > > > >> + return NULL; > >> + > >> + return pmu; > >> + } > >> + return NULL; > >> +} > >> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h > >> index 6b414cecbad2..7ff925224165 100644 > >> --- a/tools/perf/util/pmu.h > >> +++ b/tools/perf/util/pmu.h > >> @@ -289,5 +289,6 @@ int perf_pmu__pathname_fd(int dirfd, const char *pmu_name, const char *filename, > >> struct perf_pmu *perf_pmu__lookup(struct list_head *pmus, int dirfd, const char *lookup_name); > >> struct perf_pmu *perf_pmu__create_placeholder_core_pmu(struct list_head *core_pmus); > >> void perf_pmu__delete(struct perf_pmu *pmu); > >> +struct perf_pmu *pmu__find_core_pmu(void); > >> > >> #endif /* __PMU_H */ > >> -- > >> 2.34.1 > >>
| |