diff options
author | Vincent Guittot <vincent.guittot@linaro.org> | 2020-06-09 15:37:48 +0300 |
---|---|---|
committer | Peter Zijlstra <peterz@infradead.org> | 2020-06-15 15:10:04 +0300 |
commit | 3ea2f097b17e13a8280f1f9386c331b326a3dbef (patch) | |
tree | 386b638bfb54cc3bcf63311ddf1915da7ee011d0 /kernel | |
parent | b4098bfc5efb1fd7ecf40165132a1283aeea3500 (diff) | |
download | linux-3ea2f097b17e13a8280f1f9386c331b326a3dbef.tar.xz |
sched/fair: Fix NOHZ next idle balance
With commit:
'b7031a02ec75 ("sched/fair: Add NOHZ_STATS_KICK")'
rebalance_domains of the local cfs_rq happens before others idle cpus have
updated nohz.next_balance and its value is overwritten.
Move the update of nohz.next_balance for other idles cpus before balancing
and updating the next_balance of local cfs_rq.
Also, the nohz.next_balance is now updated only if all idle cpus got a
chance to rebalance their domains and the idle balance has not been aborted
because of new activities on the CPU. In case of need_resched, the idle
load balance will be kick the next jiffie in order to address remaining
ilb.
Fixes: b7031a02ec75 ("sched/fair: Add NOHZ_STATS_KICK")
Reported-by: Peng Liu <iwtbavbm@gmail.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lkml.kernel.org/r/20200609123748.18636-1-vincent.guittot@linaro.org
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/sched/fair.c | 23 |
1 files changed, 14 insertions, 9 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index a785a9b262dd..295c9ffa850b 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -10022,7 +10022,12 @@ static void kick_ilb(unsigned int flags) { int ilb_cpu; - nohz.next_balance++; + /* + * Increase nohz.next_balance only when if full ilb is triggered but + * not if we only update stats. + */ + if (flags & NOHZ_BALANCE_KICK) + nohz.next_balance = jiffies+1; ilb_cpu = find_new_ilb(); @@ -10343,6 +10348,14 @@ static bool _nohz_idle_balance(struct rq *this_rq, unsigned int flags, } } + /* + * next_balance will be updated only when there is a need. + * When the CPU is attached to null domain for ex, it will not be + * updated. + */ + if (likely(update_next_balance)) + nohz.next_balance = next_balance; + /* Newly idle CPU doesn't need an update */ if (idle != CPU_NEWLY_IDLE) { update_blocked_averages(this_cpu); @@ -10363,14 +10376,6 @@ abort: if (has_blocked_load) WRITE_ONCE(nohz.has_blocked, 1); - /* - * next_balance will be updated only when there is a need. - * When the CPU is attached to null domain for ex, it will not be - * updated. - */ - if (likely(update_next_balance)) - nohz.next_balance = next_balance; - return ret; } |