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author | Ingo Molnar <mingo@elte.hu> | 2008-05-29 09:23:17 (GMT) |
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committer | Ingo Molnar <mingo@elte.hu> | 2008-05-29 09:24:01 (GMT) |
commit | f9305d4a0968201b2818dbed0dc8cb0d4ee7aeb3 (patch) | |
tree | e171e568f04bd25c7c2ff99b5ef673b917b6eae6 /kernel | |
parent | f26a3988917913b3d11b2bd741601a2c64ab9204 (diff) | |
download | linux-fsl-qoriq-f9305d4a0968201b2818dbed0dc8cb0d4ee7aeb3.tar.xz |
revert ("sched: fair: weight calculations")
Yanmin Zhang reported:
Comparing with kernel 2.6.25, sysbench+mysql(oltp, readonly) has many
regressions with 2.6.26-rc1:
1) 8-core stoakley: 28%;
2) 16-core tigerton: 20%;
3) Itanium Montvale: 50%.
Bisect located this patch:
| 8f1bc385cfbab474db6c27b5af1e439614f3025c is first bad commit
| commit 8f1bc385cfbab474db6c27b5af1e439614f3025c
| Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
| Date: Sat Apr 19 19:45:00 2008 +0200
|
| sched: fair: weight calculations
Revert it to the 2.6.25 state.
Bisected-by: Yanmin Zhang <yanmin_zhang@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/sched.c | 9 | ||||
-rw-r--r-- | kernel/sched_fair.c | 105 |
2 files changed, 39 insertions, 75 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index cfa222a..4aac8aa 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -1368,9 +1368,6 @@ static void __resched_task(struct task_struct *p, int tif_bit) */ #define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y)) -/* - * delta *= weight / lw - */ static unsigned long calc_delta_mine(unsigned long delta_exec, unsigned long weight, struct load_weight *lw) @@ -1393,6 +1390,12 @@ calc_delta_mine(unsigned long delta_exec, unsigned long weight, return (unsigned long)min(tmp, (u64)(unsigned long)LONG_MAX); } +static inline unsigned long +calc_delta_fair(unsigned long delta_exec, struct load_weight *lw) +{ + return calc_delta_mine(delta_exec, NICE_0_LOAD, lw); +} + static inline void update_load_add(struct load_weight *lw, unsigned long inc) { lw->weight += inc; diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index e24ecd3..0eb0ae8 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -334,34 +334,6 @@ int sched_nr_latency_handler(struct ctl_table *table, int write, #endif /* - * delta *= w / rw - */ -static inline unsigned long -calc_delta_weight(unsigned long delta, struct sched_entity *se) -{ - for_each_sched_entity(se) { - delta = calc_delta_mine(delta, - se->load.weight, &cfs_rq_of(se)->load); - } - - return delta; -} - -/* - * delta *= rw / w - */ -static inline unsigned long -calc_delta_fair(unsigned long delta, struct sched_entity *se) -{ - for_each_sched_entity(se) { - delta = calc_delta_mine(delta, - cfs_rq_of(se)->load.weight, &se->load); - } - - return delta; -} - -/* * The idea is to set a period in which each task runs once. * * When there are too many tasks (sysctl_sched_nr_latency) we have to stretch @@ -390,54 +362,47 @@ static u64 __sched_period(unsigned long nr_running) */ static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se) { - return calc_delta_weight(__sched_period(cfs_rq->nr_running), se); + u64 slice = __sched_period(cfs_rq->nr_running); + + for_each_sched_entity(se) { + cfs_rq = cfs_rq_of(se); + + slice *= se->load.weight; + do_div(slice, cfs_rq->load.weight); + } + + + return slice; } /* * We calculate the vruntime slice of a to be inserted task * - * vs = s*rw/w = p + * vs = s/w = p/rw */ static u64 sched_vslice_add(struct cfs_rq *cfs_rq, struct sched_entity *se) { unsigned long nr_running = cfs_rq->nr_running; + unsigned long weight; + u64 vslice; if (!se->on_rq) nr_running++; - return __sched_period(nr_running); -} - -/* - * The goal of calc_delta_asym() is to be asymmetrically around NICE_0_LOAD, in - * that it favours >=0 over <0. - * - * -20 | - * | - * 0 --------+------- - * .' - * 19 .' - * - */ -static unsigned long -calc_delta_asym(unsigned long delta, struct sched_entity *se) -{ - struct load_weight lw = { - .weight = NICE_0_LOAD, - .inv_weight = 1UL << (WMULT_SHIFT-NICE_0_SHIFT) - }; + vslice = __sched_period(nr_running); for_each_sched_entity(se) { - struct load_weight *se_lw = &se->load; + cfs_rq = cfs_rq_of(se); - if (se->load.weight < NICE_0_LOAD) - se_lw = &lw; + weight = cfs_rq->load.weight; + if (!se->on_rq) + weight += se->load.weight; - delta = calc_delta_mine(delta, - cfs_rq_of(se)->load.weight, se_lw); + vslice *= NICE_0_LOAD; + do_div(vslice, weight); } - return delta; + return vslice; } /* @@ -454,7 +419,11 @@ __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr, curr->sum_exec_runtime += delta_exec; schedstat_add(cfs_rq, exec_clock, delta_exec); - delta_exec_weighted = calc_delta_fair(delta_exec, curr); + delta_exec_weighted = delta_exec; + if (unlikely(curr->load.weight != NICE_0_LOAD)) { + delta_exec_weighted = calc_delta_fair(delta_exec_weighted, + &curr->load); + } curr->vruntime += delta_exec_weighted; } @@ -661,17 +630,8 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial) if (!initial) { /* sleeps upto a single latency don't count. */ - if (sched_feat(NEW_FAIR_SLEEPERS)) { - unsigned long thresh = sysctl_sched_latency; - - /* - * convert the sleeper threshold into virtual time - */ - if (sched_feat(NORMALIZED_SLEEPER)) - thresh = calc_delta_fair(thresh, se); - - vruntime -= thresh; - } + if (sched_feat(NEW_FAIR_SLEEPERS)) + vruntime -= sysctl_sched_latency; /* ensure we never gain time by being placed backwards. */ vruntime = max_vruntime(se->vruntime, vruntime); @@ -1169,10 +1129,11 @@ static unsigned long wakeup_gran(struct sched_entity *se) unsigned long gran = sysctl_sched_wakeup_granularity; /* - * More easily preempt - nice tasks, while not making it harder for - * + nice tasks. + * More easily preempt - nice tasks, while not making + * it harder for + nice tasks. */ - gran = calc_delta_asym(sysctl_sched_wakeup_granularity, se); + if (unlikely(se->load.weight > NICE_0_LOAD)) + gran = calc_delta_fair(gran, &se->load); return gran; } |