runners: bench: Added litmus flag, default to disabled

The litmus benches are really only intended for introspection/debugging/
cool plots/etc. They're interesting to poke around with and cover a wide
range of littlefs's data-structures, but are not very rigorous.

To make this more clear for new users, added a new litmus flag for
benches:

  litmus = true

This doesn't change anything about how the bench is run, but serves as a
marker to hint that the bench is intended for non-rigorous benchmarking.

---

In the makefile, litmus tests are disabled by default at runtime
(--no-litmus). This is to limit `make bench` to benches that are useful
for performance comparisons.

With --no-litmus at runtime, the litmus benches are at least compiled
into the bench_runner, which should hopefully encourage keeping them up
to date with code changes. Eventually we should also run them in CI, but
only to check for runtime errors.

Unlike our tests, we're not really worried about compile time at the
moment due to how few/small our benches are.

Makefile

@@ -201,6 +201,11 @@ TESTFLAGS  += --perf-path="$(PERF)"
 BENCHFLAGS += --perf-path="$(PERF)"
 endif
 
+# default to not running litmus benches
+ifndef BENCH_ALL
+BENCHFLAGS += --no-litmus
+endif
+
 # alternative bench geometries (defaults to NOR flash)
 ifdef BENCH_NOR
 BENCHFLAGS += -DDISK_GEOMETRY=0

benches/bench_btree.toml

@@ -23,6 +23,8 @@ defines.SEED = 42
 # 0x2 => lookup
 # 0x8 => usage
 defines.MASK = 0xb
+# not the most rigorous
+litmus = true
 in = 'lfs3.c'
 code = '''
     lfs3_t lfs3;
@@ -124,6 +126,8 @@ defines.SEED = 42
 # 0x4 => namelookup
 # 0x8 => usage
 defines.MASK = 0xf
+# not the most rigorous
+litmus = true
 in = 'lfs3.c'
 code = '''
     lfs3_t lfs3;

benches/bench_dir.toml

@@ -22,6 +22,8 @@ defines.SEED = 42
 # 0x4 => read
 # 0x8 => usage
 defines.MASK = 0xf
+# not the most rigorous
+litmus = true
 code = '''
     lfs3_t lfs3;
     lfs3_format(&lfs3, LFS3_F_RDWR, CFG) => 0;

benches/bench_file.toml

@@ -24,6 +24,8 @@ defines.SEED = 42
 # 0x2 => read
 # 0x4 => usage
 defines.MASK = 0x7
+# not the most rigorous
+litmus = true
 code = '''
     lfs3_t lfs3;
     lfs3_format(&lfs3, LFS3_F_RDWR, CFG) => 0;

benches/bench_rbyd.toml

@@ -27,6 +27,8 @@ defines.SEED = 42
 # 0x08 => lookup
 # 0x10 => usage
 defines.MASK = 0x1f
+# not the most rigorous
+litmus = true
 in = 'lfs3.c'
 code = '''
     lfs3_t lfs3;
@@ -138,6 +140,8 @@ defines.SEED = 42
 # 0x08 => lookup
 # 0x10 => usage
 defines.MASK = 0x1f
+# not the most rigorous
+litmus = true
 in = 'lfs3.c'
 code = '''
     lfs3_t lfs3;

runners/bench_runner.c

@@ -1306,8 +1306,9 @@ static void summary(void) {
     char perm_buf[64];
     sprintf(perm_buf, "%zu/%zu", perms.filtered, perms.total);
     char flag_buf[64];
-    sprintf(flag_buf, "%s%s",
+    sprintf(flag_buf, "%s%s%s",
             (flags & BENCH_INTERNAL) ? "i" : "",
+            (flags & BENCH_LITMUS)   ? "l" : "",
             (!flags)                 ? "-" : "");
     printf("%-23s  %7s %7zu %7zu %15s\n",
             "TOTAL",
@@ -1363,10 +1364,12 @@ static void list_suites(void) {
 
             char perm_buf[64];
             sprintf(perm_buf, "%zu/%zu", perms.filtered, perms.total);
+            bench_flags_t flags = bench_suites[i]->flags;
             char flag_buf[64];
-            sprintf(flag_buf, "%s%s",
+            sprintf(flag_buf, "%s%s%s",
-                    (bench_suites[i]->flags & BENCH_INTERNAL)  ? "i" : "",
+                    (flags & BENCH_INTERNAL) ? "i" : "",
-                    (!bench_suites[i]->flags)                  ? "-" : "");
+                    (flags & BENCH_LITMUS)   ? "l" : "",
+                    (!flags)                 ? "-" : "");
             printf("%-*s  %7s %7zu %15s\n",
                     name_width,
                     bench_suites[i]->name,
@@ -1415,12 +1418,12 @@ static void list_cases(void) {
 
                 char perm_buf[64];
                 sprintf(perm_buf, "%zu/%zu", perms.filtered, perms.total);
+                bench_flags_t flags = bench_suites[i]->cases[j].flags;
                 char flag_buf[64];
-                sprintf(flag_buf, "%s%s",
+                sprintf(flag_buf, "%s%s%s",
-                        (bench_suites[i]->cases[j].flags & BENCH_INTERNAL)
+                        (flags & BENCH_INTERNAL) ? "i" : "",
-                            ? "i" : "",
+                        (flags & BENCH_LITMUS)   ? "l" : "",
-                        (!bench_suites[i]->cases[j].flags)
+                        (!flags)                 ? "-" : "");
-                            ? "-" : "");
                 printf("%-*s  %7s %15s\n",
                         name_width,
                         bench_suites[i]->cases[j].name,
@@ -1948,14 +1951,15 @@ enum opt_flags {
     OPT_STEP                     = 's',
     OPT_FORCE                    = 7,
     OPT_NO_INTERNAL              = 8,
+    OPT_NO_LITMUS                = 9,
     OPT_DISK                     = 'd',
     OPT_TRACE                    = 't',
-    OPT_TRACE_BACKTRACE          = 9,
+    OPT_TRACE_BACKTRACE          = 10,
-    OPT_TRACE_PERIOD             = 10,
+    OPT_TRACE_PERIOD             = 11,
-    OPT_TRACE_FREQ               = 11,
+    OPT_TRACE_FREQ               = 12,
-    OPT_READ_SLEEP               = 12,
+    OPT_READ_SLEEP               = 13,
-    OPT_PROG_SLEEP               = 13,
+    OPT_PROG_SLEEP               = 14,
-    OPT_ERASE_SLEEP              = 14,
+    OPT_ERASE_SLEEP              = 15,
 };
 
 const char *short_opts = "hYlLD:s:d:t:";
@@ -1977,6 +1981,7 @@ const struct option long_opts[] = {
     {"step",             required_argument, NULL, OPT_STEP},
     {"force",            no_argument,       NULL, OPT_FORCE},
     {"no-internal",      no_argument,       NULL, OPT_NO_INTERNAL},
+    {"no-litmus",        no_argument,       NULL, OPT_NO_LITMUS},
     {"disk",             required_argument, NULL, OPT_DISK},
     {"trace",            required_argument, NULL, OPT_TRACE},
     {"trace-backtrace",  no_argument,       NULL, OPT_TRACE_BACKTRACE},
@@ -2003,6 +2008,7 @@ const char *const help_text[] = {
     "Comma-separated range of permutations to run.",
     "Ignore bench filters.",
     "Don't run internal benches.",
+    "Don't run litmus benches.",
     "Direct block device operations to this file.",
     "Direct trace output to this file.",
     "Include a backtrace with every trace statement.",
@@ -2333,6 +2339,10 @@ int main(int argc, char **argv) {
             bench_mask |= BENCH_INTERNAL;
             break;
 
+        case OPT_NO_LITMUS:;
+            bench_mask |= BENCH_LITMUS;
+            break;
+
         case OPT_DISK:;
             bench_disk_path = optarg;
             break;

runners/bench_runner.h

@@ -83,6 +83,7 @@ struct lfs3_cfg;
 
 enum bench_flags {
     BENCH_INTERNAL  = 0x1,
+    BENCH_LITMUS    = 0x2,
 };
 typedef uint8_t bench_flags_t;
 

runners/test_runner.c

@@ -1206,12 +1206,13 @@ static void list_suites(void) {
 
             char perm_buf[64];
             sprintf(perm_buf, "%zu/%zu", perms.filtered, perms.total);
+            test_flags_t flags = test_suites[i]->flags;
             char flag_buf[64];
             sprintf(flag_buf, "%s%s%s%s",
-                    (test_suites[i]->flags & TEST_INTERNAL)  ? "i" : "",
+                    (flags & TEST_INTERNAL)  ? "i" : "",
-                    (test_suites[i]->flags & TEST_REENTRANT) ? "r" : "",
+                    (flags & TEST_REENTRANT) ? "r" : "",
-                    (test_suites[i]->flags & TEST_FUZZ)      ? "f" : "",
+                    (flags & TEST_FUZZ)      ? "f" : "",
-                    (!test_suites[i]->flags)                 ? "-" : "");
+                    (!flags)                 ? "-" : "");
             printf("%-*s  %7s %7zu %15s\n",
                     name_width,
                     test_suites[i]->name,
@@ -1260,16 +1261,13 @@ static void list_cases(void) {
 
                 char perm_buf[64];
                 sprintf(perm_buf, "%zu/%zu", perms.filtered, perms.total);
+                test_flags_t flags = test_suites[i]->cases[j].flags;
                 char flag_buf[64];
                 sprintf(flag_buf, "%s%s%s%s",
-                        (test_suites[i]->cases[j].flags & TEST_INTERNAL)
+                        (flags & TEST_INTERNAL)  ? "i" : "",
-                            ? "i" : "",
+                        (flags & TEST_REENTRANT) ? "r" : "",
-                        (test_suites[i]->cases[j].flags & TEST_REENTRANT)
+                        (flags & TEST_FUZZ)      ? "f" : "",
-                            ? "r" : "",
+                        (!flags)                 ? "-" : "");
-                        (test_suites[i]->cases[j].flags & TEST_FUZZ)
-                            ? "f" : "",
-                        (!test_suites[i]->cases[j].flags)
-                            ? "-" : "");
                 printf("%-*s  %7s %15s\n",
                         name_width,
                         test_suites[i]->cases[j].name,

scripts/bench.py

@@ -106,6 +106,10 @@ class BenchCase:
                 config.pop('suite_internal', None))
         if self.internal is None:
             self.internal = False
+        self.litmus = config.pop('litmus',
+                config.pop('suite_litmus', None))
+        if self.litmus is None:
+            self.litmus = False
 
         # in implies internal
         self.internal |= bool(self.in_)
@@ -287,6 +291,7 @@ class BenchSuite:
             # a couple of these we just forward to all cases
             defines = config.pop('defines', None)
             internal = config.pop('internal', None)
+            litmus = config.pop('litmus', None)
 
             self.cases = []
             for name, config_ in cases.items():
@@ -298,12 +303,15 @@ class BenchSuite:
                             'suite_defines': defines,
                             'suite_in': self.in_,
                             'suite_internal': internal,
+                            'suite_litmus': litmus,
                             **config_},
                         args)
 
                 # skipping internal benches?
                 if args.get('no_internal') and case.internal:
                     continue
+                if args.get('no_litmus') and case.litmus:
+                    continue
 
                 self.cases.append(case)
 
@@ -316,6 +324,7 @@ class BenchSuite:
 
             # combine other per-case things
             self.internal = any(case.internal for case in self.cases)
+            self.litmus = any(case.litmus for case in self.cases)
 
         for k in config.keys():
             print('%swarning:%s in %s, found unused key %r' % (
@@ -596,7 +605,8 @@ def compile(bench_paths, **args):
                 f.writeln(4*' '+'.path = "%s",' % suite.path)
                 f.writeln(4*' '+'.flags = %s,' % (
                         ' | '.join(filter(None, [
-                                'BENCH_INTERNAL' if suite.internal else None]))
+                                'BENCH_INTERNAL' if suite.internal else None,
+                                'BENCH_LITMUS' if suite.litmus else None]))
                             or 0))
                 for ifdef in suite.ifdef:
                     f.writeln(4*' '+'#if (%s)' % re.sub(
@@ -628,6 +638,8 @@ def compile(bench_paths, **args):
                         f.writeln(12*' '+'.flags = %s,' % (
                                 ' | '.join(filter(None, [
                                         'BENCH_INTERNAL' if case.internal
+                                            else None,
+                                        'BENCH_LITMUS' if case.litmus
                                             else None]))
                                     or 0))
                         for ifdef in it.chain(suite.ifdef, case.ifdef):
@@ -798,6 +810,8 @@ def find_runner(runner, id=None, main=True, **args):
         cmd.append('--force')
     if args.get('no_internal'):
         cmd.append('--no-internal')
+    if args.get('no_litmus'):
+        cmd.append('--no-litmus')
 
     # only one thread should write to disk/trace, otherwise the output
     # ends up clobbered and useless
@@ -1714,6 +1728,10 @@ if __name__ == "__main__":
             '--no-internal',
             action='store_true',
             help="Don't run internal benches.")
+    bench_parser.add_argument(
+            '--no-litmus',
+            action='store_true',
+            help="Don't run litmus benches.")
     bench_parser.add_argument(
             '-d', '--disk',
             help="Direct block device operations to this file.")
@@ -1876,6 +1894,10 @@ if __name__ == "__main__":
             '--no-internal',
             action='store_true',
             help="Don't build internal benches.")
+    comp_parser.add_argument(
+            '--no-litmus',
+            action='store_true',
+            help="Don't build litmus benches.")
 
     # do the thing
     args = parser.parse_intermixed_args()