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sched: Fix missing sched tunable recalculation on cpu add/remove

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Based on Peter Zijlstras patch suggestion this enables recalculation of
the scheduler tunables in response of a change in the number of cpus. It
also adds a max of eight cpus that are considered in that scaling.

Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1259579808-11357-2-git-send-email-ehrhardt@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Christian Ehrhardt
2009-11-30 12:16:46 +01:00
committed by Ingo Molnar
parent 57785df5ac
commit 0bcdcf28c9
2 changed files with 33 additions and 14 deletions
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31
kernel/sched.c
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@ -814,6 +814,7 @@ const_debug unsigned int sysctl_sched_nr_migrate = 32;
* default: 0.25ms
*/
unsigned int sysctl_sched_shares_ratelimit = 250000;
unsigned int normalized_sysctl_sched_shares_ratelimit = 250000;
/*
* Inject some fuzzyness into changing the per-cpu group shares
@ -1814,6 +1815,7 @@ static void cfs_rq_set_shares(struct cfs_rq *cfs_rq, unsigned long shares)
#endif
static void calc_load_account_active(struct rq *this_rq);
static void update_sysctl(void);
static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
{
@ -7028,22 +7030,23 @@ cpumask_var_t nohz_cpu_mask;
*
* This idea comes from the SD scheduler of Con Kolivas:
*/
static void update_sysctl(void)
{
unsigned int cpus = min(num_online_cpus(), 8U);
unsigned int factor = 1 + ilog2(cpus);
#define SET_SYSCTL(name) \
(sysctl_##name = (factor) * normalized_sysctl_##name)
SET_SYSCTL(sched_min_granularity);
SET_SYSCTL(sched_latency);
SET_SYSCTL(sched_wakeup_granularity);
SET_SYSCTL(sched_shares_ratelimit);
#undef SET_SYSCTL
}
static inline void sched_init_granularity(void)
{
unsigned int factor = 1 + ilog2(num_online_cpus());
const unsigned long limit = 200000000;
sysctl_sched_min_granularity *= factor;
if (sysctl_sched_min_granularity > limit)
sysctl_sched_min_granularity = limit;
sysctl_sched_latency *= factor;
if (sysctl_sched_latency > limit)
sysctl_sched_latency = limit;
sysctl_sched_wakeup_granularity *= factor;
sysctl_sched_shares_ratelimit *= factor;
update_sysctl();
}
#ifdef CONFIG_SMP