selftests/bpf: Add benchmark for dynptr key support in hash map

The patch adds a benchmark test to compare the lookup and update/delete
performance between normal hash map and dynptr-keyed hash map. It also
compares the memory usage of these two maps after fill up these two
maps.

The benchmark simulates the case when the map key is composed of a
8-bytes integer and a variable-size string. Now the integer just saves
the length of the string. These strings will be randomly generated by
default, and they can also be specified by a external file (e.g., the
output from awk '{print $3}' /proc/kallsyms).

The key definitions for dynptr-keyed and normal hash map are defined as
shown below:

struct dynptr_key {
	__u64 cookie;
	struct bpf_dynptr desc;
}

struct norm_key {
	__u64 cookie;
	char desc[MAX_STR_SIZE];
};

The lookup or update procedure will first lookup an array to get the key
of hash map. The returned value from the array is the same as norm_key
definition. For normal hash map, it will use the returned value to
manipulate the hash map directly. For dynptr-keyed hash map, it will
construct a bpf_dynptr object from the returned value (the value of
cookie is the same as the string length), then passes the key to
dynptr-keyed hash map. Because the lookup procedure is lockless,
therefore, each producer during lookup test will lookup the whole hash
map. However, update and deletion procedures have lock, therefore, each
producer during update test only updates different part of the hash map.

The following is the benchmark results when running the benchmark under a
8-CPUs VM:

(1) Randomly generate 128K strings (max_size=256, entries=128K)

ENTRIES=131072 ./benchs/run_bench_dynptr_key.sh

normal hash map
===============
htab-lookup-p1-131072 2.977 ± 0.017M/s (drops 0.006 ± 0.000M/s, mem 64.984 MiB)
htab-lookup-p2-131072 6.033 ± 0.048M/s (drops 0.015 ± 0.000M/s, mem 64.966 MiB)
htab-lookup-p4-131072 11.612 ± 0.063M/s (drops 0.026 ± 0.000M/s, mem 64.984 MiB)
htab-lookup-p8-131072 22.918 ± 0.315M/s (drops 0.055 ± 0.001M/s, mem 64.966 MiB)
htab-update-p1-131072 2.121 ± 0.014M/s (drops 0.000 ± 0.000M/s, mem 64.986 MiB)
htab-update-p2-131072 4.138 ± 0.047M/s (drops 0.000 ± 0.000M/s, mem 64.986 MiB)
htab-update-p4-131072 7.378 ± 0.078M/s (drops 0.000 ± 0.000M/s, mem 64.986 MiB)
htab-update-p8-131072 13.774 ± 0.129M/s (drops 0.000 ± 0.000M/s, mem 64.986 MiB)

dynptr-keyed hash map
=====================
htab-lookup-p1-131072 3.891 ± 0.008M/s (drops 0.009 ± 0.000M/s, mem 34.908 MiB)
htab-lookup-p2-131072 7.467 ± 0.054M/s (drops 0.016 ± 0.000M/s, mem 34.925 MiB)
htab-lookup-p4-131072 15.151 ± 0.054M/s (drops 0.030 ± 0.000M/s, mem 34.992 MiB)
htab-lookup-p8-131072 29.461 ± 0.448M/s (drops 0.076 ± 0.001M/s, mem 34.910 MiB)
htab-update-p1-131072 2.085 ± 0.124M/s (drops 0.000 ± 0.000M/s, mem 34.888 MiB)
htab-update-p2-131072 3.278 ± 0.068M/s (drops 0.000 ± 0.000M/s, mem 34.888 MiB)
htab-update-p4-131072 6.840 ± 0.100M/s (drops 0.000 ± 0.000M/s, mem 35.023 MiB)
htab-update-p8-131072 11.837 ± 0.190M/s (drops 0.000 ± 0.000M/s, mem 34.941 MiB)

(2) Use strings in /proc/kallsyms (max_size=82, entries=150K)

STR_FILE=kallsyms.txt ./benchs/run_bench_dynptr_key.sh

normal hash map
===============
htab-lookup-p1-kallsyms.txt 7.201 ± 0.080M/s (drops 0.482 ± 0.005M/s, mem 26.384 MiB)
htab-lookup-p2-kallsyms.txt 14.217 ± 0.114M/s (drops 0.951 ± 0.008M/s, mem 26.384 MiB)
htab-lookup-p4-kallsyms.txt 29.293 ± 0.141M/s (drops 1.959 ± 0.010M/s, mem 26.384 MiB)
htab-lookup-p8-kallsyms.txt 58.406 ± 0.384M/s (drops 3.906 ± 0.026M/s, mem 26.384 MiB)
htab-update-p1-kallsyms.txt 3.864 ± 0.036M/s (drops 0.000 ± 0.000M/s, mem 26.387 MiB)
htab-update-p2-kallsyms.txt 5.757 ± 0.078M/s (drops 0.000 ± 0.000M/s, mem 26.387 MiB)
htab-update-p4-kallsyms.txt 10.195 ± 0.655M/s (drops 0.000 ± 0.000M/s, mem 26.387 MiB)
htab-update-p8-kallsyms.txt 18.203 ± 0.165M/s (drops 0.000 ± 0.000M/s, mem 26.387 MiB)

dynptr-keyed hash map
=====================
htab-lookup-p1-kallsyms.txt 7.223 ± 0.007M/s (drops 0.483 ± 0.003M/s, mem 20.993 MiB)
htab-lookup-p2-kallsyms.txt 14.350 ± 0.035M/s (drops 0.960 ± 0.004M/s, mem 20.968 MiB)
htab-lookup-p4-kallsyms.txt 29.317 ± 0.153M/s (drops 1.960 ± 0.013M/s, mem 20.963 MiB)
htab-lookup-p8-kallsyms.txt 58.787 ± 0.662M/s (drops 3.931 ± 0.047M/s, mem 21.018 MiB)
htab-update-p1-kallsyms.txt 2.503 ± 0.124M/s (drops 0.000 ± 0.000M/s, mem 20.972 MiB)
htab-update-p2-kallsyms.txt 4.622 ± 0.422M/s (drops 0.000 ± 0.000M/s, mem 21.104 MiB)
htab-update-p4-kallsyms.txt 8.374 ± 0.149M/s (drops 0.000 ± 0.000M/s, mem 21.027 MiB)
htab-update-p8-kallsyms.txt 14.608 ± 0.319M/s (drops 0.000 ± 0.000M/s, mem 21.027 MiB)

Signed-off-by: Hou Tao <[email protected]>

tools/testing/selftests/bpf/Makefile

@@ -811,6 +811,7 @@ $(OUTPUT)/bench_local_storage_create.o: $(OUTPUT)/bench_local_storage_create.ske
 $(OUTPUT)/bench_bpf_hashmap_lookup.o: $(OUTPUT)/bpf_hashmap_lookup.skel.h
 $(OUTPUT)/bench_htab_mem.o: $(OUTPUT)/htab_mem_bench.skel.h
 $(OUTPUT)/bench_bpf_crypto.o: $(OUTPUT)/crypto_bench.skel.h
+$(OUTPUT)/bench_dynptr_key.o: $(OUTPUT)/dynptr_key_bench.skel.h
 $(OUTPUT)/bench.o: bench.h testing_helpers.h $(BPFOBJ)
 $(OUTPUT)/bench: LDLIBS += -lm
 $(OUTPUT)/bench: $(OUTPUT)/bench.o \
@@ -831,6 +832,7 @@ $(OUTPUT)/bench: $(OUTPUT)/bench.o \
 		 $(OUTPUT)/bench_local_storage_create.o \
 		 $(OUTPUT)/bench_htab_mem.o \
 		 $(OUTPUT)/bench_bpf_crypto.o \
+		 $(OUTPUT)/bench_dynptr_key.o \
 		 #
 	$(call msg,BINARY,,$@)
 	$(Q)$(CC) $(CFLAGS) $(LDFLAGS) $(filter %.a %.o,$^) $(LDLIBS) -o $@

tools/testing/selftests/bpf/bench.c

@@ -283,6 +283,7 @@ extern struct argp bench_local_storage_create_argp;
 extern struct argp bench_htab_mem_argp;
 extern struct argp bench_trigger_batch_argp;
 extern struct argp bench_crypto_argp;
+extern struct argp bench_dynptr_key_argp;
 
 static const struct argp_child bench_parsers[] = {
 	{ &bench_ringbufs_argp, 0, "Ring buffers benchmark", 0 },
@@ -297,6 +298,7 @@ static const struct argp_child bench_parsers[] = {
 	{ &bench_htab_mem_argp, 0, "hash map memory benchmark", 0 },
 	{ &bench_trigger_batch_argp, 0, "BPF triggering benchmark", 0 },
 	{ &bench_crypto_argp, 0, "bpf crypto benchmark", 0 },
+	{ &bench_dynptr_key_argp, 0, "dynptr key benchmark", 0 },
 	{},
 };
 
@@ -549,6 +551,10 @@ extern const struct bench bench_local_storage_create;
 extern const struct bench bench_htab_mem;
 extern const struct bench bench_crypto_encrypt;
 extern const struct bench bench_crypto_decrypt;
+extern const struct bench bench_norm_htab_lookup;
+extern const struct bench bench_dynkey_htab_lookup;
+extern const struct bench bench_norm_htab_update;
+extern const struct bench bench_dynkey_htab_update;
 
 static const struct bench *benchs[] = {
 	&bench_count_global,
@@ -609,6 +615,10 @@ static const struct bench *benchs[] = {
 	&bench_htab_mem,
 	&bench_crypto_encrypt,
 	&bench_crypto_decrypt,
+	&bench_norm_htab_lookup,
+	&bench_dynkey_htab_lookup,
+	&bench_norm_htab_update,
+	&bench_dynkey_htab_update,
 };
 
 static void find_benchmark(void)