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authorThomas Gleixner <tglx@linutronix.de>2019-08-21 21:09:21 +0200
committerThomas Gleixner <tglx@linutronix.de>2019-08-28 11:50:41 +0200
commit8ea1de90a5eccdc18c8f05f8596bae8660a3ff9a (patch)
treebce49bbca194dbcd1dc972248723925d764ed989 /kernel/time
parent1cd07c0b94f2c320270d76edb7dd49bceb09c1df (diff)
downloadlinux-8ea1de90a5eccdc18c8f05f8596bae8660a3ff9a.tar.bz2
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 <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lkml.kernel.org/r/20190821192922.458286860@linutronix.de
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/posix-cpu-timers.c24
1 files changed, 14 insertions, 10 deletions
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index caafdfdd6f0f..dcdf9c8241b1 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;
}