Messages in this thread Patch in this message | | | Date | Wed, 14 May 2008 19:14:14 +0530 | From | Srivatsa Vaddagiri <> | Subject | Re: volanoMark regression with kernel 2.6.26-rc1 |
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On Mon, May 12, 2008 at 11:20:47AM +0200, Peter Zijlstra wrote: > It looks like things like find_busiest_group() just think everything is > peachy when the imbalance is < 1 task - which with all this grouping > stuff is not necessarily true.
fwiw, the following hack seems to help bring down regression to ~5% (b/n 2.6.25 and 2.6.26-rc1 with USER_SCHED):
Also in the patch GROUP_SCALE can probably be less than what I used (and needs a ifdef GROUP_SCHED) ..
Not-signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
--- kernel/sched.c | 4 ++++ kernel/sched_fair.c | 14 +++++--------- kernel/sched_features.h | 2 +- 3 files changed, 10 insertions(+), 10 deletions(-)
Index: current/kernel/sched.c =================================================================== --- current.orig/kernel/sched.c +++ current/kernel/sched.c @@ -1551,13 +1551,17 @@ static void cpuacct_charge(struct task_s static inline void cpuacct_charge(struct task_struct *tsk, u64 cputime) {} #endif +#define GROUP_SCALE (2*1024) + static inline void inc_cpu_load(struct rq *rq, unsigned long load) { + load *= GROUP_SCALE; update_load_add(&rq->load, load); } static inline void dec_cpu_load(struct rq *rq, unsigned long load) { + load *= GROUP_SCALE; update_load_sub(&rq->load, load); } Index: current/kernel/sched_fair.c =================================================================== --- current.orig/kernel/sched_fair.c +++ current/kernel/sched_fair.c @@ -1393,24 +1393,20 @@ load_balance_fair(struct rq *this_rq, in unsigned long this_weight, busiest_weight; long rem_load, max_load, moved_load; + busiest_weight = tg->cfs_rq[busiest_cpu]->task_weight; /* * empty group */ - if (!aggregate(tg, sd)->task_weight) + if (!aggregate(tg, sd)->task_weight || !busiest_weight) continue; rem_load = rem_load_move * aggregate(tg, sd)->rq_weight; rem_load /= aggregate(tg, sd)->load + 1; - this_weight = tg->cfs_rq[this_cpu]->task_weight; - busiest_weight = tg->cfs_rq[busiest_cpu]->task_weight; - - imbalance = (busiest_weight - this_weight) / 2; - - if (imbalance < 0) - imbalance = busiest_weight; + if (!rem_load) + continue; - max_load = max(rem_load, imbalance); + max_load = rem_load; moved_load = __load_balance_fair(this_rq, this_cpu, busiest, max_load, sd, idle, all_pinned, this_best_prio, tg->cfs_rq[busiest_cpu]); Index: current/kernel/sched_features.h =================================================================== --- current.orig/kernel/sched_features.h +++ current/kernel/sched_features.h @@ -6,5 +6,5 @@ SCHED_FEAT(CACHE_HOT_BUDDY, 1) SCHED_FEAT(SYNC_WAKEUPS, 1) SCHED_FEAT(HRTICK, 1) SCHED_FEAT(DOUBLE_TICK, 0) -SCHED_FEAT(NORMALIZED_SLEEPER, 1) +SCHED_FEAT(NORMALIZED_SLEEPER, 0) SCHED_FEAT(DEADLINE, 1) -- Regards, vatsa
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