lkml.org 
[lkml]   [2019]   [Jul]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[RFC][PATCH 01/13] sched/deadline: Impose global limits on sched_attr::sched_period

Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Luca Abeni <luca.abeni@santannapisa.it>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
include/linux/sched/sysctl.h | 3 +++
kernel/sched/deadline.c | 23 +++++++++++++++++++++--
kernel/sysctl.c | 14 ++++++++++++++
3 files changed, 38 insertions(+), 2 deletions(-)

--- a/include/linux/sched/sysctl.h
+++ b/include/linux/sched/sysctl.h
@@ -56,6 +56,9 @@ int sched_proc_update_handler(struct ctl
extern unsigned int sysctl_sched_rt_period;
extern int sysctl_sched_rt_runtime;

+extern unsigned int sysctl_sched_dl_period_max;
+extern unsigned int sysctl_sched_dl_period_min;
+
#ifdef CONFIG_UCLAMP_TASK
extern unsigned int sysctl_sched_uclamp_util_min;
extern unsigned int sysctl_sched_uclamp_util_max;
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2597,6 +2597,14 @@ void __getparam_dl(struct task_struct *p
}

/*
+ * Default limits for DL period; on the top end we guard against small util
+ * tasks still getting rediculous long effective runtimes, on the bottom end we
+ * guard against timer DoS.
+ */
+unsigned int sysctl_sched_dl_period_max = 1 << 22; /* ~4 seconds */
+unsigned int sysctl_sched_dl_period_min = 100; /* 100 us */
+
+/*
* This function validates the new parameters of a -deadline task.
* We ask for the deadline not being zero, and greater or equal
* than the runtime, as well as the period of being zero or
@@ -2608,6 +2616,8 @@ void __getparam_dl(struct task_struct *p
*/
bool __checkparam_dl(const struct sched_attr *attr)
{
+ u64 period, max, min;
+
/* special dl tasks don't actually use any parameter */
if (attr->sched_flags & SCHED_FLAG_SUGOV)
return true;
@@ -2631,12 +2641,21 @@ bool __checkparam_dl(const struct sched_
attr->sched_period & (1ULL << 63))
return false;

+ period = attr->sched_period;
+ if (!period)
+ period = attr->sched_deadline;
+
/* runtime <= deadline <= period (if period != 0) */
- if ((attr->sched_period != 0 &&
- attr->sched_period < attr->sched_deadline) ||
+ if (period < attr->sched_deadline ||
attr->sched_deadline < attr->sched_runtime)
return false;

+ max = (u64)READ_ONCE(sysctl_sched_dl_period_max) * NSEC_PER_USEC;
+ min = (u64)READ_ONCE(sysctl_sched_dl_period_min) * NSEC_PER_USEC;
+
+ if (period < min || period > max)
+ return false;
+
return true;
}

--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -443,6 +443,20 @@ static struct ctl_table kern_table[] = {
.proc_handler = sched_rt_handler,
},
{
+ .procname = "sched_deadline_period_max_us",
+ .data = &sysctl_sched_dl_period_max,
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
+ {
+ .procname = "sched_deadline_period_min_us",
+ .data = &sysctl_sched_dl_period_min,
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
+ {
.procname = "sched_rr_timeslice_ms",
.data = &sysctl_sched_rr_timeslice,
.maxlen = sizeof(int),

\
 
 \ /
  Last update: 2019-07-26 18:21    [W:0.316 / U:35.852 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site