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sched: fix next_interval determination in idle_balance()

The intervals of domains that do not have SD_BALANCE_NEWIDLE must be
considered for the calculation of the time of the next balance. Otherwise
we may defer rebalancing forever.

Siddha also spotted that the conversion of the balance interval
to jiffies is missing. Fix that to.

From: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>

also continue the loop if !(sd->flags & SD_LOAD_BALANCE).

Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

It did in fact trigger under all three of mainline, CFS, and -rt including CFS
-- see below for a couple of emails from last Friday giving results for these
three on the AMD box (where it happened) and on a single-quad NUMA-Q system
(where it did not, at least not with such severity).

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

authored by

Christoph Lameter and committed by
Linus Torvalds 92c4ca5c 84966343

+13 -9
+13 -9
kernel/sched.c
··· 2938 2938 unsigned long next_balance = jiffies + 60 * HZ; 2939 2939 2940 2940 for_each_domain(this_cpu, sd) { 2941 - if (sd->flags & SD_BALANCE_NEWIDLE) { 2941 + unsigned long interval; 2942 + 2943 + if (!(sd->flags & SD_LOAD_BALANCE)) 2944 + continue; 2945 + 2946 + if (sd->flags & SD_BALANCE_NEWIDLE) 2942 2947 /* If we've pulled tasks over stop searching: */ 2943 2948 pulled_task = load_balance_newidle(this_cpu, 2944 - this_rq, sd); 2945 - if (time_after(next_balance, 2946 - sd->last_balance + sd->balance_interval)) 2947 - next_balance = sd->last_balance 2948 - + sd->balance_interval; 2949 - if (pulled_task) 2950 - break; 2951 - } 2949 + this_rq, sd); 2950 + 2951 + interval = msecs_to_jiffies(sd->balance_interval); 2952 + if (time_after(next_balance, sd->last_balance + interval)) 2953 + next_balance = sd->last_balance + interval; 2954 + if (pulled_task) 2955 + break; 2952 2956 } 2953 2957 if (!pulled_task) 2954 2958 /*