From: "tip-bot2 for Arnd Bergmann" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
linux-kernel@vger.kernel.org
Subject: [tip: timers/core] time: Optimize ns_to_timespec64()
Date: Tue, 12 Nov 2019 07:22:44 -0000 [thread overview]
Message-ID: <157354336402.29376.17172070392776098039.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20191108203435.112759-3-arnd@arndb.de>
The following commit has been merged into the timers/core branch of tip:
Commit-ID: 20d087368d38c7350a4519a3b316ef7eb2504692
Gitweb: https://git.kernel.org/tip/20d087368d38c7350a4519a3b316ef7eb2504692
Author: Arnd Bergmann <arnd@arndb.de>
AuthorDate: Fri, 08 Nov 2019 21:34:25 +01:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Tue, 12 Nov 2019 08:15:15 +01:00
time: Optimize ns_to_timespec64()
ns_to_timespec64() calls div_s64_rem(), which is a rather slow function on
32-bit architectures, as it cannot take advantage of the do_div()
optimizations for constant arguments.
Open-code the div_s64_rem() function in ns_to_timespec64(), so a constant
divider can be passed into the optimized div_u64_rem() function.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20191108203435.112759-3-arnd@arndb.de
---
kernel/time/time.c | 21 ++++++++++++---------
1 file changed, 12 insertions(+), 9 deletions(-)
diff --git a/kernel/time/time.c b/kernel/time/time.c
index 5c54ca6..45a3589 100644
--- a/kernel/time/time.c
+++ b/kernel/time/time.c
@@ -550,18 +550,21 @@ EXPORT_SYMBOL(set_normalized_timespec64);
*/
struct timespec64 ns_to_timespec64(const s64 nsec)
{
- struct timespec64 ts;
+ struct timespec64 ts = { 0, 0 };
s32 rem;
- if (!nsec)
- return (struct timespec64) {0, 0};
-
- ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem);
- if (unlikely(rem < 0)) {
- ts.tv_sec--;
- rem += NSEC_PER_SEC;
+ if (likely(nsec > 0)) {
+ ts.tv_sec = div_u64_rem(nsec, NSEC_PER_SEC, &rem);
+ ts.tv_nsec = rem;
+ } else if (nsec < 0) {
+ /*
+ * With negative times, tv_sec points to the earlier
+ * second, and tv_nsec counts the nanoseconds since
+ * then, so tv_nsec is always a positive number.
+ */
+ ts.tv_sec = -div_u64_rem(-nsec - 1, NSEC_PER_SEC, &rem) - 1;
+ ts.tv_nsec = NSEC_PER_SEC - rem - 1;
}
- ts.tv_nsec = rem;
return ts;
}
next prev parent reply other threads:[~2019-11-12 7:22 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-08 20:34 [PATCH 0/8] y2038: bug fixes from y2038 work Arnd Bergmann
2019-11-08 20:34 ` [PATCH 1/8] y2038: timex: remove incorrect time_t truncation Arnd Bergmann
2019-11-10 20:44 ` Deepa Dinamani
2019-11-12 7:16 ` [tip: timers/urgent] ntp/y2038: Remove " tip-bot2 for Arnd Bergmann
2019-11-08 20:34 ` [PATCH 2/8] timekeeping: optimize ns_to_timespec64 Arnd Bergmann
2019-11-10 20:46 ` Deepa Dinamani
2019-11-12 7:22 ` tip-bot2 for Arnd Bergmann [this message]
2019-11-08 20:34 ` [PATCH 3/8] powerpc: fix vdso32 for ppc64le Arnd Bergmann
2019-11-20 19:13 ` [Y2038] " Ben Hutchings
2019-11-20 19:35 ` Arnd Bergmann
2019-11-20 21:49 ` Ben Hutchings
2019-11-21 10:02 ` Arnd Bergmann
2019-11-21 15:56 ` Ben Hutchings
2019-11-08 20:34 ` [PATCH 4/8] ipmi: kill off 'timespec' usage again Arnd Bergmann
2019-11-08 22:11 ` Corey Minyard
2019-11-09 11:23 ` Arnd Bergmann
2019-11-08 20:34 ` [PATCH 5/8] netfilter: xt_time: use time64_t Arnd Bergmann
2019-11-15 22:43 ` Pablo Neira Ayuso
2019-11-08 20:34 ` [PATCH 6/8] lp: fix sparc64 LPSETTIMEOUT ioctl Arnd Bergmann
2019-11-20 19:27 ` [Y2038] " Ben Hutchings
2019-11-20 19:46 ` Arnd Bergmann
2019-11-20 22:10 ` Ben Hutchings
2019-11-21 14:04 ` Arnd Bergmann
2019-11-21 16:00 ` Ben Hutchings
2019-11-08 20:34 ` [PATCH 7/8] ppdev: fix PPGETTIME/PPSETTIME ioctls Arnd Bergmann
2019-11-20 19:29 ` [Y2038] " Ben Hutchings
2019-11-21 14:06 ` Arnd Bergmann
2019-11-08 20:34 ` [PATCH 8/8] Input: input_event: fix struct padding on sparc64 Arnd Bergmann
2019-11-11 18:28 ` Dmitry Torokhov
2019-11-11 19:18 ` Arnd Bergmann
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