This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
[PATCH v2][BZ #12515] Improve precision of clock function
- From: Siddhesh Poyarekar <siddhesh at redhat dot com>
- To: OndÅej BÃlka <neleai at seznam dot cz>
- Cc: libc-alpha at sourceware dot org
- Date: Tue, 21 May 2013 21:04:42 +0530
- Subject: [PATCH v2][BZ #12515] Improve precision of clock function
- References: <20130521145611 dot GM8927 at spoyarek dot pnq dot redhat dot com> <20130521151839 dot GA18430 at domone dot kolej dot mff dot cuni dot cz>
On Tue, May 21, 2013 at 05:18:39PM +0200, OndÅej BÃlka wrote:
> No, you said CLOCK_PROCESS_CPUTIME_ID but you wrote
> > + if (__clock_gettime (CLOCK_REALTIME, &ts) == 0)
Here's the real patch now, retested to ensure that I'm getting good
values. Sorry about the sloppiness.
I should have mentioned that this needs the hidden_def patch I posted
for __clock_gettime so that it doesn't break the check-localplt test.
Thanks,
Siddhesh
[BZ #12515]
* sysdeps/unix/sysv/linux/clock.c (clock): Use result from
CLOCK_PROCESS_CPUTIME_ID clock if available.
diff --git a/sysdeps/unix/sysv/linux/clock.c b/sysdeps/unix/sysv/linux/clock.c
index 5268d33..4142c6d 100644
--- a/sysdeps/unix/sysv/linux/clock.c
+++ b/sysdeps/unix/sysv/linux/clock.c
@@ -23,6 +23,14 @@
clock_t
clock (void)
{
+ struct timespec ts;
+
+ if (__clock_gettime (CLOCK_PROCESS_CPUTIME_ID, &ts) == 0)
+ return (clock_t) ((ts.tv_nsec * CLOCKS_PER_SEC) / 1000000000
+ + ts.tv_sec * CLOCKS_PER_SEC);
+
+ /* clock_gettime failed. This will only occur if CLOCK_PROCESS_CPUTIME_ID is
+ not supported by the kernel. Fall back to __times. */
struct tms buf;
long clk_tck = __sysconf (_SC_CLK_TCK);