From a4d1b3e2caf21000a0611df97133233a8302859a Mon Sep 17 00:00:00 2001
From: winlin <winlin@vip.126.com>
Date: Tue, 22 Dec 2020 17:36:18 +0800
Subject: [PATCH] Research: Add cost analysis

---
 trunk/research/st/cost.cpp | 135 +++++++++++++++++++++++++++++++++++++
 1 file changed, 135 insertions(+)
 create mode 100644 trunk/research/st/cost.cpp

diff --git a/trunk/research/st/cost.cpp b/trunk/research/st/cost.cpp
new file mode 100644
index 000000000..ac6602d89
--- /dev/null
+++ b/trunk/research/st/cost.cpp
@@ -0,0 +1,135 @@
+/*
+g++ -g -O0 cost.cpp -o cost && ./cost | grep COST
+*/
+#include <stdio.h>
+#include <sys/time.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#define SRS_UTIME_MILLISECONDS 1000
+#define srsu2i(us) ((int)(us))
+#define srsu2ms(us) ((us) / SRS_UTIME_MILLISECONDS)
+#define srsu2msi(us) int((us) / SRS_UTIME_MILLISECONDS)
+
+int64_t srs_update_system_time()
+{
+    timeval now;
+    ::gettimeofday(&now, NULL);
+    return ((int64_t)now.tv_sec) * 1000 * 1000 + (int64_t)now.tv_usec;
+}
+
+int main(int argc, char** argv)
+{
+    // The cost for srs_update_system_time() itself.
+    if (true) {
+        int64_t start = srs_update_system_time();
+
+        int64_t ts_gettimeofday = srs_update_system_time();
+
+        printf("[COST] gettimeofday=%dus\n", srsu2i(ts_gettimeofday - start));
+    }
+
+    // The cost for allocate 1MB memory.
+    if (true) {
+        int64_t start = srs_update_system_time();
+
+        int size = 1024 * 1024;
+        char* p = new char[size];
+        int64_t ts_allocate = srs_update_system_time();
+
+        for (int i = 0; i < size; i++) {
+            p[i] = 0x0F;
+        }
+        int64_t ts_init = srs_update_system_time();
+
+        printf("[COST] new[%d]=%dus, init=%dus\n",
+            size,
+            srsu2i(ts_allocate - start),
+            srsu2i(ts_init - ts_allocate)
+        );
+    }
+
+    // The cost for printf.
+    if (true) {
+        int64_t start = srs_update_system_time();
+
+        printf("TEST: OK\n");
+        int64_t ts_printf = srs_update_system_time();
+
+        printf("TEST: OK OK\n");
+        int64_t ts_printf2 = srs_update_system_time();
+
+        printf("TEST: OK OK %s\n", "OK");
+        int64_t ts_printf3 = srs_update_system_time();
+
+        printf("[COST] printf=%dus %dus %dus\n",
+            srsu2i(ts_printf - start),
+            srsu2i(ts_printf2 - ts_printf),
+            srsu2i(ts_printf3 - ts_printf2)
+        );
+    }
+
+    // The cost for file open or close.
+    if (true) {
+        int64_t start = srs_update_system_time();
+
+        int fd = ::open("cost.log", O_RDWR | O_CREAT | O_APPEND, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+        int64_t ts_open = srs_update_system_time();
+
+        ::close(fd);
+        int64_t ts_close = srs_update_system_time();
+
+        printf("[COST] open=%dus, close=%dus\n",
+            srsu2i(ts_open - start),
+            srsu2i(ts_close - ts_open)
+        );
+    }
+
+    // The cost for file writing.
+    if (true) {
+        int64_t start = srs_update_system_time();
+
+        int fd = ::open("cost.log", O_RDWR | O_CREAT | O_APPEND, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+        int64_t ts_open = srs_update_system_time();
+
+        ::write(fd, "Hello\n", 6);
+        int64_t ts_write = srs_update_system_time();
+
+        ::write(fd, "HelloHello\n", 12);
+        int64_t ts_write2 = srs_update_system_time();
+
+        ::close(fd);
+        int64_t ts_close = srs_update_system_time();
+
+        printf("[COST] write=%dus %dus\n",
+            srsu2i(ts_write - ts_open),
+            srsu2i(ts_write2 - ts_write)
+        );
+    }
+
+    // The cost for file reading.
+    if (true) {
+        char buf[128];
+        int64_t start = srs_update_system_time();
+
+        int fd = ::open("cost.log", O_RDWR | O_CREAT | O_APPEND, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+        int64_t ts_open = srs_update_system_time();
+
+        ::read(fd, buf, 6);
+        int64_t ts_read = srs_update_system_time();
+
+        ::read(fd, buf, 6);
+        int64_t ts_read2 = srs_update_system_time();
+
+        ::close(fd);
+        int64_t ts_close = srs_update_system_time();
+
+        printf("[COST] read=%dus %dus\n",
+            srsu2i(ts_read - ts_open),
+            srsu2i(ts_read2 - ts_read)
+        );
+    }
+
+    return 0;
+}
+