From: Richard Cochran <richardcochran@gmail.com>
To: vatikaharlalka@gmail.com
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
Preeti U Murthy <preeti@linux.vnet.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
linux-kernel@vger.kernel.org
Subject: get_nohz_timer_target?
Date: Mon, 18 Apr 2016 15:37:09 +0200 [thread overview]
Message-ID: <20160418133709.GA10358@localhost.localdomain> (raw)
Looking at kernel/sched/core.c:get_nohz_timer_target(), I don't
understand the change made in:
commit 9642d18eee2cd169b60c6ac0f20bda745b5a3d1e
Author: Vatika Harlalka <vatikaharlalka@gmail.com>
Date: Tue Sep 1 16:50:59 2015 +0200
nohz: Affine unpinned timers to housekeepers
After that change, the code now reads like this:
int i, cpu = smp_processor_id();
struct sched_domain *sd;
if (!idle_cpu(cpu) && is_housekeeping_cpu(cpu))
return cpu;
rcu_read_lock();
for_each_domain(cpu, sd) {
for_each_cpu(i, sched_domain_span(sd)) {
if (!idle_cpu(i) && is_housekeeping_cpu(cpu)) {
--------------------------------------------------------------- ^^^
Was this supposed to be 'i' instead?
If not, how does this test make any sense?
In any case, testing over and over again is surely wasteful.
---------------------------------------------------------------
cpu = i;
goto unlock;
}
}
}
if (!is_housekeeping_cpu(cpu))
cpu = housekeeping_any_cpu();
unlock:
rcu_read_unlock();
return cpu;
Thanks,
Richard
next reply other threads:[~2016-04-18 13:37 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-18 13:37 Richard Cochran [this message]
2016-07-08 9:05 ` get_nohz_timer_target? Thomas Gleixner
2016-07-08 11:49 ` get_nohz_timer_target? Frederic Weisbecker
2016-07-08 16:48 ` get_nohz_timer_target? Thomas Gleixner
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