From: David Lamparter <equinox@diac24.net>
Date: Tue, 13 Apr 2021 18:49:26 +0000 (+0200)
Subject: lib: try CLOCK_THREAD_CPUTIME_ID
X-Git-Tag: frr-8.2.2~814^2~3
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=6418e2d34273256a7f9fae71dff92a96403101ff;p=mirror_frr.git

lib: try CLOCK_THREAD_CPUTIME_ID

This might be faster if at some point in the future the Linux vDSO
supports CLOCK_THREAD_CPUTIME_ID without making a syscall.  (Same
applies for other OSes.)

Signed-off-by: David Lamparter <equinox@diac24.net>
---

diff --git a/configure.ac b/configure.ac
index 9ba95fe98..0ea209bbf 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2229,6 +2229,10 @@ AC_CHECK_DECL([CLOCK_MONOTONIC],
 	 AC_DEFINE([HAVE_CLOCK_MONOTONIC], [1], [Have monotonic clock])
 ], [AC_MSG_RESULT([no])], [FRR_INCLUDES])
 
+AC_CHECK_DECL([CLOCK_THREAD_CPUTIME_ID], [
+	 AC_DEFINE([HAVE_CLOCK_THREAD_CPUTIME_ID], [1], [Have cpu-time clock])
+], [AC_MSG_RESULT([no])], [FRR_INCLUDES])
+
 AC_SEARCH_LIBS([clock_nanosleep], [rt], [
   AC_DEFINE([HAVE_CLOCK_NANOSLEEP], [1], [Have clock_nanosleep()])
 ])
diff --git a/lib/thread.c b/lib/thread.c
index dd5c1fed4..835aa3811 100644
--- a/lib/thread.c
+++ b/lib/thread.c
@@ -1821,9 +1821,14 @@ static unsigned long timeval_elapsed(struct timeval a, struct timeval b)
 unsigned long thread_consumed_time(RUSAGE_T *now, RUSAGE_T *start,
 				   unsigned long *cputime)
 {
+#ifdef HAVE_CLOCK_THREAD_CPUTIME_ID
+	*cputime = (now->cpu.tv_sec - start->cpu.tv_sec) * TIMER_SECOND_MICRO
+		   + (now->cpu.tv_nsec - start->cpu.tv_nsec) / 1000;
+#else
 	/* This is 'user + sys' time.  */
 	*cputime = timeval_elapsed(now->cpu.ru_utime, start->cpu.ru_utime)
 		   + timeval_elapsed(now->cpu.ru_stime, start->cpu.ru_stime);
+#endif
 	return timeval_elapsed(now->real, start->real);
 }
 
@@ -1856,14 +1861,25 @@ void thread_set_yield_time(struct thread *thread, unsigned long yield_time)
 
 void thread_getrusage(RUSAGE_T *r)
 {
+	monotime(&r->real);
+	if (!cputime_enabled) {
+		memset(&r->cpu, 0, sizeof(r->cpu));
+		return;
+	}
+
+#ifdef HAVE_CLOCK_THREAD_CPUTIME_ID
+	/* not currently implemented in Linux's vDSO, but maybe at some point
+	 * in the future?
+	 */
+	clock_gettime(CLOCK_THREAD_CPUTIME_ID, &r->cpu);
+#else /* !HAVE_CLOCK_THREAD_CPUTIME_ID */
 #if defined RUSAGE_THREAD
 #define FRR_RUSAGE RUSAGE_THREAD
 #else
 #define FRR_RUSAGE RUSAGE_SELF
 #endif
-	monotime(&r->real);
-	if (cputime_enabled)
-		getrusage(FRR_RUSAGE, &(r->cpu));
+	getrusage(FRR_RUSAGE, &(r->cpu));
+#endif
 }
 
 /*
diff --git a/lib/thread.h b/lib/thread.h
index 737ed005c..abd94ff4f 100644
--- a/lib/thread.h
+++ b/lib/thread.h
@@ -41,7 +41,11 @@ extern unsigned long cputime_threshold;
 extern unsigned long walltime_threshold;
 
 struct rusage_t {
+#ifdef HAVE_CLOCK_THREAD_CPUTIME_ID
+	struct timespec cpu;
+#else
 	struct rusage cpu;
+#endif
 	struct timeval real;
 };
 #define RUSAGE_T        struct rusage_t