The following commit has been merged into the timers/core branch of tip: Commit-ID: 8ea1de90a5eccdc18c8f05f8596bae8660a3ff9a Gitweb: https://git.kernel.org/tip/8ea1de90a5eccdc18c8f05f8596bae8660a3ff9a Author: Thomas Gleixner <t...@linutronix.de> AuthorDate: Wed, 21 Aug 2019 21:09:21 +02:00 Committer: Thomas Gleixner <t...@linutronix.de> CommitterDate: Wed, 28 Aug 2019 11:50:41 +02:00
posix-cpu-timers: Get rid of 64bit divisions Instead of dividing A to match the units of B it's more efficient to multiply B to match the units of A. Signed-off-by: Thomas Gleixner <t...@linutronix.de> Reviewed-by: Frederic Weisbecker <frede...@kernel.org> Link: https://lkml.kernel.org/r/20190821192922.458286...@linutronix.de --- kernel/time/posix-cpu-timers.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index caafdfd..dcdf9c8 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -798,10 +798,11 @@ static void check_thread_timers(struct task_struct *tsk, */ soft = task_rlimit(tsk, RLIMIT_RTTIME); if (soft != RLIM_INFINITY) { + /* Task RT timeout is accounted in jiffies. RTTIME is usec */ + unsigned long rtim = tsk->rt.timeout * (USEC_PER_SEC / HZ); unsigned long hard = task_rlimit_max(tsk, RLIMIT_RTTIME); - if (hard != RLIM_INFINITY && - tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) { + if (hard != RLIM_INFINITY && rtim >= hard) { /* * At the hard limit, we just die. * No need to calculate anything else now. @@ -813,7 +814,7 @@ static void check_thread_timers(struct task_struct *tsk, __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk); return; } - if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) { + if (rtim >= soft) { /* * At the soft limit, send a SIGXCPU every second. */ @@ -910,11 +911,13 @@ static void check_process_timers(struct task_struct *tsk, soft = task_rlimit(tsk, RLIMIT_CPU); if (soft != RLIM_INFINITY) { - u64 softns, ptime = samples[CPUCLOCK_PROF]; + /* RLIMIT_CPU is in seconds. Samples are nanoseconds */ unsigned long hard = task_rlimit_max(tsk, RLIMIT_CPU); - unsigned long psecs = div_u64(ptime, NSEC_PER_SEC); + u64 ptime = samples[CPUCLOCK_PROF]; + u64 softns = (u64)soft * NSEC_PER_SEC; + u64 hardns = (u64)hard * NSEC_PER_SEC; - if (hard != RLIM_INFINITY && psecs >= hard) { + if (hard != RLIM_INFINITY && ptime >= hardns) { /* * At the hard limit, we just die. * No need to calculate anything else now. @@ -926,7 +929,7 @@ static void check_process_timers(struct task_struct *tsk, __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk); return; } - if (psecs >= soft) { + if (ptime >= softns) { /* * At the soft limit, send a SIGXCPU every second. */ @@ -936,11 +939,12 @@ static void check_process_timers(struct task_struct *tsk, } __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk); if (soft < hard) { - soft++; - sig->rlim[RLIMIT_CPU].rlim_cur = soft; + sig->rlim[RLIMIT_CPU].rlim_cur = soft + 1; + softns += NSEC_PER_SEC; } } - softns = soft * NSEC_PER_SEC; + + /* Update the expiry cache */ if (softns < pct->bases[CPUCLOCK_PROF].nextevt) pct->bases[CPUCLOCK_PROF].nextevt = softns; }
