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| author | Thomas Gleixner <tglx@linutronix.de> | 2019-08-21 21:09:21 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2019-08-28 11:50:41 +0200 |
| commit | 8ea1de90a5eccdc18c8f05f8596bae8660a3ff9a (patch) | |
| tree | bce49bbca194dbcd1dc972248723925d764ed989 /kernel/time | |
| parent | 1cd07c0b94f2c320270d76edb7dd49bceb09c1df (diff) | |
| download | linux-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.c | 24 |
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; } |