Inspired by https://forum.nginx.org/read.php?21,282919 -- print CPU ticks to Nginx debug log

ngx_log_cputicks.patch

diff -r 992bf7540a98 src/core/ngx_log.c
--- a/src/core/ngx_log.c	Thu Feb 07 19:39:35 2019 +0300
+++ b/src/core/ngx_log.c	Sat Feb 09 13:14:06 2019 +0300
@@ -16,6 +16,8 @@ static void ngx_log_insert(ngx_log_t *lo
 
 #if (NGX_DEBUG)
 
+static u_char *ngx_log_cputicks(u_char *p, u_char *last);
+
 static void ngx_log_memory_writer(ngx_log_t *log, ngx_uint_t level,
     u_char *buf, size_t len);
 static void ngx_log_memory_cleanup(void *data);
@@ -145,6 +147,14 @@ ngx_log_error_core(ngx_uint_t level, ngx
         p = ngx_log_errno(p, last, err);
     }
 
+#if (NGX_DEBUG)
+
+    if (level >= NGX_LOG_DEBUG) {
+        p = ngx_log_cputicks(p, last);
+    }
+
+#endif
+
     if (level != NGX_LOG_DEBUG && log->handler) {
         p = log->handler(log, p, last - p);
     }
@@ -712,6 +722,17 @@ ngx_log_insert(ngx_log_t *log, ngx_log_t
 
 #if (NGX_DEBUG)
 
+static u_char*
+ngx_log_cputicks(u_char *p, u_char *last)
+{
+    uint64_t lo = 0, hi = 0, ticks = 0;
+
+    __asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi));
+    ticks = ((u_int64_t)hi << 32) | lo;
+
+    return ngx_sprintf(p, " cputicks=%uL", ticks);
+}
+
 static void
 ngx_log_memory_writer(ngx_log_t *log, ngx_uint_t level, u_char *buf,
     size_t len)