linux-kernel - [PATCH v2] sched/fair: fix update the nohz.next_balance even if we haven't done any load balance

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1427442750-8112-1-git-send-email-wanpeng.li@linux.intel.com>
Date:	Fri, 27 Mar 2015 15:52:30 +0800
From:	Wanpeng Li <wanpeng.li@...ux.intel.com>
To:	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Jason Low <jason.low2@...com>,
	Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org,
	Wanpeng Li <wanpeng.li@...ux.intel.com>
Subject: [PATCH v2] sched/fair: fix update the nohz.next_balance even if we haven't done any load balance

As Srikar pointed out (https://lkml.org/lkml/2015/3/27/26):

| With the current code when the ilb cpus are not free:
| - We would be updating the nohz.next_balance even through we havent done
|   any load balance.
| - We might iterate thro the nohz.idle_cpus_mask()s to find balance_cpus.

This patch fix it by adding need_resched check with the idle check, and
keep the need_resched check in for loop to catch ilb get busy.

Suggested-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Reviewed-by: Jason Low <jason.low2@...com>
Signed-off-by: Wanpeng Li <wanpeng.li@...ux.intel.com>
---
 kernel/sched/fair.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 0576ce0..788e42f 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7638,7 +7638,7 @@ static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle)
 	struct rq *rq;
 	int balance_cpu;
 
-	if (idle != CPU_IDLE ||
+	if (idle != CPU_IDLE || need_resched() ||
 	    !test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu)))
 		goto end;
 
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/