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* [glibc] Use clock_gettime to implement time.
@ 2019-10-30 20:23 Adhemerval Zanella
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From: Adhemerval Zanella @ 2019-10-30 20:23 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=0d563783490bf5b2d7d52cab205760fdff5d5650
commit 0d563783490bf5b2d7d52cab205760fdff5d5650
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Thu Oct 24 17:52:30 2019 +0000
Use clock_gettime to implement time.
Change the default implementation of time to call clock_gettime,
to align with new Linux ports that are expected to only implement
__NR_clock_gettime. Arch-specific implementation that either call
the time vDSO or route to gettimeofday vDSO are not removed.
Also for Linux, CLOCK_REALTIME_COARSE is used instead of generic
CLOCK_REALTIME clockid. This takes less CPU time and its behavior
better matches what the current glibc does.
Checked on x86_64-linux-gnu, i686-linux-gnu, powerpc64le-linux-gnu,
powerpc64-linux-gnu, powerpc-linux-gnu, and aarch64-linux-gnu.
Co-authored-by: Zack Weinberg <zackw@panix.com>
Reviewed-by: Lukasz Majewski <lukma@denx.de>
Diff:
---
.../sysv/linux/time.c => generic/time-clockid.h} | 29 +++------------------
sysdeps/unix/sysv/linux/powerpc/time.c | 2 +-
.../time.c => unix/sysv/linux/time-clockid.h} | 30 +++++-----------------
time/time.c | 13 +++++-----
4 files changed, 17 insertions(+), 57 deletions(-)
diff --git a/sysdeps/unix/sysv/linux/time.c b/sysdeps/generic/time-clockid.h
similarity index 64%
rename from sysdeps/unix/sysv/linux/time.c
rename to sysdeps/generic/time-clockid.h
index f461733..13db6e6 100644
--- a/sysdeps/unix/sysv/linux/time.c
+++ b/sysdeps/generic/time-clockid.h
@@ -1,4 +1,5 @@
-/* Copyright (C) 2005-2019 Free Software Foundation, Inc.
+/* System specific time definitions. Generic Version.
+ Copyright 2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -15,27 +16,5 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
-#include <stddef.h>
-#include <time.h>
-
-#include <sysdep.h>
-
-#ifdef __NR_time
-
-time_t
-time (time_t *t)
-{
- INTERNAL_SYSCALL_DECL (err);
- time_t res = INTERNAL_SYSCALL (time, err, 1, NULL);
- /* There cannot be any error. */
- if (t != NULL)
- *t = res;
- return res;
-}
-libc_hidden_def (time)
-
-#else
-
-# include <sysdeps/posix/time.c>
-
-#endif
+/* Timer used on clock_gettime for time implementation. */
+#define TIME_CLOCK_GETTIME_CLOCKID CLOCK_REALTIME
diff --git a/sysdeps/unix/sysv/linux/powerpc/time.c b/sysdeps/unix/sysv/linux/powerpc/time.c
index c35b80f..e957b81 100644
--- a/sysdeps/unix/sysv/linux/powerpc/time.c
+++ b/sysdeps/unix/sysv/linux/powerpc/time.c
@@ -78,6 +78,6 @@ libc_hidden_def (time)
#else
-#include <sysdeps/posix/time.c>
+#include <time/time.c>
#endif /* !SHARED */
diff --git a/sysdeps/posix/time.c b/sysdeps/unix/sysv/linux/time-clockid.h
similarity index 57%
rename from sysdeps/posix/time.c
rename to sysdeps/unix/sysv/linux/time-clockid.h
index 0ab31bd..1bdaa18 100644
--- a/sysdeps/posix/time.c
+++ b/sysdeps/unix/sysv/linux/time-clockid.h
@@ -1,4 +1,5 @@
-/* Copyright (C) 1991-2019 Free Software Foundation, Inc.
+/* System specific time definitions. Generic Version.
+ Copyright 2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
@@ -15,26 +16,7 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
-#include <stddef.h> /* For NULL. */
-#include <time.h>
-#include <sys/time.h>
-
-
-/* Return the current time as a `time_t' and also put it in *T if T is
- not NULL. Time is represented as seconds from Jan 1 00:00:00 1970. */
-time_t
-time (time_t *t)
-{
- struct timeval tv;
- time_t result;
-
- if (__gettimeofday (&tv, (struct timezone *) NULL))
- result = (time_t) -1;
- else
- result = (time_t) tv.tv_sec;
-
- if (t != NULL)
- *t = result;
- return result;
-}
-libc_hidden_def (time)
+/* Timer used on clock_gettime for time implementation. For Linux
+ it uses the coarse version which returns the time at the last tick
+ and mimic what time as syscall should return. */
+#define TIME_CLOCK_GETTIME_CLOCKID CLOCK_REALTIME_COARSE
diff --git a/time/time.c b/time/time.c
index b53a06e..e6e5eef 100644
--- a/time/time.c
+++ b/time/time.c
@@ -15,19 +15,18 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
-#include <errno.h>
#include <time.h>
+#include <time-clockid.h>
/* Return the time now, and store it in *TIMER if not NULL. */
time_t
time (time_t *timer)
{
- __set_errno (ENOSYS);
+ struct timespec ts;
+ __clock_gettime (TIME_CLOCK_GETTIME_CLOCKID, &ts);
- if (timer != NULL)
- *timer = (time_t) -1;
- return (time_t) -1;
+ if (timer)
+ *timer = ts.tv_sec;
+ return ts.tv_sec;
}
libc_hidden_def (time)
-
-stub_warning (time)
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