Re: [PATCH bpf-next 6/6] selftest/bpf/benchs: Add benchmark for hashmap lookups

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On 1/27/23 10:14 AM, Anton Protopopov wrote:
+/* The number of slots to store times */
+#define NR_SLOTS 32
+
+/* Configured by userspace */
+u64 nr_entries;
+u64 nr_loops;
+u32 __attribute__((__aligned__(8))) key[256];
+
+/* Filled by us */
+u64 __attribute__((__aligned__(256))) percpu_times_index[NR_SLOTS]; > +u64 __attribute__((__aligned__(256))) percpu_times[256][NR_SLOTS];
+
+static inline void patch_key(u32 i)
+{
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	key[0] = i + 1;
+#else
+	key[0] = __builtin_bswap32(i + 1);
+#endif
+	/* the rest of key is random and is configured by userspace */
+}
+
+static int lookup_callback(__u32 index, u32 *unused)
+{
+	patch_key(index);
+	return bpf_map_lookup_elem(&hash_map_bench, key) ? 0 : 1;
+}
+
+static int loop_lookup_callback(__u32 index, u32 *unused)
+{
+	return bpf_loop(nr_entries, lookup_callback, NULL, 0) ? 0 : 1;
+}
+
+SEC("fentry/" SYS_PREFIX "sys_getpgid")
+int benchmark(void *ctx)
+{
+	u32 cpu = bpf_get_smp_processor_id();
+	u32 times_index;
+	u64 start_time;
+
+	times_index = percpu_times_index[cpu & 255] % NR_SLOTS;

percpu_times_index only has NR_SLOTS (32) elements?

+	start_time = bpf_ktime_get_ns();
+	bpf_loop(nr_loops, loop_lookup_callback, NULL, 0);
+	percpu_times[cpu & 255][times_index] = bpf_ktime_get_ns() - start_time;
+	percpu_times_index[cpu & 255] += 1;
+	return 0;
+}




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