[v2,05/11] Use clock_gettime to implement time.
Commit Message
Use clock_gettime to implement time.
Changes from previous version:
- Do not remove Linux arch-specific implementations.
- Use CLOCK_REALTIME_COARSE for Linux.
--
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>
---
sysdeps/unix/sysv/linux/powerpc/time.c | 2 +-
.../sysv/linux/{time.c => time-internal.h} | 31 ++++---------------
sysdeps/posix/time.c => time/time-internal.h | 28 +++--------------
time/time.c | 13 ++++----
4 files changed, 17 insertions(+), 57 deletions(-)
rename sysdeps/unix/sysv/linux/{time.c => time-internal.h} (64%)
rename sysdeps/posix/time.c => time/time-internal.h (57%)
Comments
On Fri, 25 Oct 2019 09:08:26 -0300
Adhemerval Zanella <adhemerval.zanella@linaro.org> wrote:
> Use clock_gettime to implement time.
>
> Changes from previous version:
>
> - Do not remove Linux arch-specific implementations.
>
> - Use CLOCK_REALTIME_COARSE for Linux.
>
> --
>
> 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>
> ---
> sysdeps/unix/sysv/linux/powerpc/time.c | 2 +-
> .../sysv/linux/{time.c => time-internal.h} | 31
> ++++--------------- sysdeps/posix/time.c => time/time-internal.h |
> 28 +++-------------- time/time.c |
> 13 ++++---- 4 files changed, 17 insertions(+), 57 deletions(-)
> rename sysdeps/unix/sysv/linux/{time.c => time-internal.h} (64%)
> rename sysdeps/posix/time.c => time/time-internal.h (57%)
>
> diff --git a/sysdeps/unix/sysv/linux/powerpc/time.c
> b/sysdeps/unix/sysv/linux/powerpc/time.c index c35b80fad1..e957b81751
> 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/unix/sysv/linux/time.c
> b/sysdeps/unix/sysv/linux/time-internal.h similarity index 64%
> rename from sysdeps/unix/sysv/linux/time.c
> rename to sysdeps/unix/sysv/linux/time-internal.h
> index f461733678..c4c5f6b643 100644
> --- a/sysdeps/unix/sysv/linux/time.c
> +++ b/sysdeps/unix/sysv/linux/time-internal.h
> @@ -1,4 +1,5 @@
> -/* Copyright (C) 2005-2019 Free Software Foundation, Inc.
> +/* Internals of time and related functions. Linux 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 +16,7 @@
> 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. 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/sysdeps/posix/time.c b/time/time-internal.h
> similarity index 57%
> rename from sysdeps/posix/time.c
> rename to time/time-internal.h
> index 0ab31bd7b6..f448f64191 100644
> --- a/sysdeps/posix/time.c
> +++ b/time/time-internal.h
> @@ -1,4 +1,5 @@
> -/* Copyright (C) 1991-2019 Free Software Foundation, Inc.
> +/* Internals of time and related functions.
> + 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 +16,5 @@
> 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. */
> +#define TIME_CLOCK_GETTIME_CLOCKID CLOCK_REALTIME
> diff --git a/time/time.c b/time/time.c
> index b53a06e29c..09a2b4fc88 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-internal.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)
Reviewed-by: Lukasz Majewski <lukma@denx.de>
Best regards,
Lukasz Majewski
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de
@@ -78,6 +78,6 @@ libc_hidden_def (time)
#else
-#include <sysdeps/posix/time.c>
+#include <time/time.c>
#endif /* !SHARED */
similarity index 64%
rename from sysdeps/unix/sysv/linux/time.c
rename to sysdeps/unix/sysv/linux/time-internal.h
@@ -1,4 +1,5 @@
-/* Copyright (C) 2005-2019 Free Software Foundation, Inc.
+/* Internals of time and related functions. Linux 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 +16,7 @@
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. 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
similarity index 57%
rename from sysdeps/posix/time.c
rename to time/time-internal.h
@@ -1,4 +1,5 @@
-/* Copyright (C) 1991-2019 Free Software Foundation, Inc.
+/* Internals of time and related functions.
+ 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 +16,5 @@
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. */
+#define TIME_CLOCK_GETTIME_CLOCKID CLOCK_REALTIME
@@ -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-internal.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)