From: Peter Zijlstra <peterz@infradead.org>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-block@vger.kernel.org, cgroups@vger.kernel.org,
Ingo Molnar <mingo@redhat.com>,
Andrew Morton <akpm@linuxfoundation.org>,
Tejun Heo <tj@kernel.org>, Balbir Singh <bsingharora@gmail.com>,
Mike Galbraith <efault@gmx.de>, Oliver Yang <yangoliver@me.com>,
Shakeel Butt <shakeelb@google.com>, xxx xxx <x.qendo@gmail.com>,
Taras Kondratiuk <takondra@cisco.com>,
Daniel Walker <danielwa@cisco.com>,
Vinayak Menon <vinmenon@codeaurora.org>,
Ruslan Ruslichenko <rruslich@cisco.com>,
kernel-team@fb.com
Subject: Re: [PATCH 6/7] psi: pressure stall information for CPU, memory, and IO
Date: Wed, 9 May 2018 12:21:00 +0200 [thread overview]
Message-ID: <20180509102100.GN12217@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180507210135.1823-7-hannes@cmpxchg.org>
On Mon, May 07, 2018 at 05:01:34PM -0400, Johannes Weiner wrote:
> +/**
> + * psi_memstall_enter - mark the beginning of a memory stall section
> + * @flags: flags to handle nested sections
> + *
> + * Marks the calling task as being stalled due to a lack of memory,
> + * such as waiting for a refault or performing reclaim.
> + */
> +void psi_memstall_enter(unsigned long *flags)
> +{
> + struct rq_flags rf;
> + struct rq *rq;
> +
> + *flags = current->flags & PF_MEMSTALL;
> + if (*flags)
> + return;
> + /*
> + * PF_MEMSTALL setting & accounting needs to be atomic wrt
> + * changes to the task's scheduling state, otherwise we can
> + * race with CPU migration.
> + */
> + local_irq_disable();
> + rq = this_rq();
> + raw_spin_lock(&rq->lock);
> + rq_pin_lock(rq, &rf);
Given that churn in sched.h, you seen rq_lock() and friends.
Either write this like:
local_irq_disable();
rq = this_rq();
rq_lock(rq, &rf);
Or instroduce "rq = this_rq_lock_irq()", which we could also use in
do_sched_yield().
> + update_rq_clock(rq);
> +
> + current->flags |= PF_MEMSTALL;
> + psi_task_change(current, rq_clock(rq), 0, TSK_MEMSTALL);
> +
> + rq_unpin_lock(rq, &rf);
> + raw_spin_unlock(&rq->lock);
> + local_irq_enable();
That's called rq_unlock_irq().
> +}
> +
> +/**
> + * psi_memstall_leave - mark the end of an memory stall section
> + * @flags: flags to handle nested memdelay sections
> + *
> + * Marks the calling task as no longer stalled due to lack of memory.
> + */
> +void psi_memstall_leave(unsigned long *flags)
> +{
> + struct rq_flags rf;
> + struct rq *rq;
> +
> + if (*flags)
> + return;
> + /*
> + * PF_MEMSTALL clearing & accounting needs to be atomic wrt
> + * changes to the task's scheduling state, otherwise we could
> + * race with CPU migration.
> + */
> + local_irq_disable();
> + rq = this_rq();
> + raw_spin_lock(&rq->lock);
> + rq_pin_lock(rq, &rf);
> +
> + update_rq_clock(rq);
> +
> + current->flags &= ~PF_MEMSTALL;
> + psi_task_change(current, rq_clock(rq), TSK_MEMSTALL, 0);
> +
> + rq_unpin_lock(rq, &rf);
> + raw_spin_unlock(&rq->lock);
> + local_irq_enable();
> +}
Idem.
next prev parent reply other threads:[~2018-05-09 10:21 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-07 21:01 [PATCH 0/7] psi: pressure stall information for CPU, memory, and IO Johannes Weiner
2018-05-07 21:01 ` [PATCH 1/7] mm: workingset: don't drop refault information prematurely Johannes Weiner
2018-05-07 21:01 ` [PATCH 2/7] mm: workingset: tell cache transitions from workingset thrashing Johannes Weiner
2018-05-07 21:01 ` [PATCH 3/7] delayacct: track delays from thrashing cache pages Johannes Weiner
2018-05-07 21:01 ` [PATCH 4/7] sched: loadavg: consolidate LOAD_INT, LOAD_FRAC, CALC_LOAD Johannes Weiner
2018-05-07 21:01 ` [PATCH 5/7] sched: loadavg: make calc_load_n() public Johannes Weiner
2018-05-09 9:49 ` Peter Zijlstra
2018-05-10 13:46 ` Johannes Weiner
2018-05-07 21:01 ` [PATCH 6/7] psi: pressure stall information for CPU, memory, and IO Johannes Weiner
2018-05-08 0:42 ` Randy Dunlap
2018-05-08 14:06 ` Johannes Weiner
2018-05-08 1:35 ` kbuild test robot
2018-05-08 3:04 ` kbuild test robot
2018-05-08 14:05 ` Johannes Weiner
2018-05-09 9:59 ` Peter Zijlstra
2018-05-10 13:49 ` Johannes Weiner
2018-05-09 10:04 ` Peter Zijlstra
2018-05-10 14:10 ` Johannes Weiner
2018-05-09 10:05 ` Peter Zijlstra
2018-05-10 14:13 ` Johannes Weiner
2018-05-09 10:14 ` Peter Zijlstra
2018-05-10 14:18 ` Johannes Weiner
2018-05-09 10:21 ` Peter Zijlstra [this message]
2018-05-10 14:24 ` Johannes Weiner
2018-05-09 10:26 ` Peter Zijlstra
2018-05-09 10:46 ` Peter Zijlstra
2018-05-09 11:38 ` Peter Zijlstra
2018-05-10 13:41 ` Johannes Weiner
2018-05-14 8:33 ` Peter Zijlstra
2018-05-09 10:55 ` Peter Zijlstra
2018-05-09 11:03 ` Vinayak Menon
2018-05-23 13:17 ` Johannes Weiner
2018-05-23 13:19 ` Vinayak Menon
2018-06-07 0:46 ` Suren Baghdasaryan
2018-05-07 21:01 ` [PATCH 7/7] psi: cgroup support Johannes Weiner
2018-05-09 11:07 ` Peter Zijlstra
2018-05-10 14:49 ` Johannes Weiner
2018-05-14 15:39 ` [PATCH 0/7] psi: pressure stall information for CPU, memory, and IO Christopher Lameter
2018-05-14 17:35 ` Bart Van Assche
2018-05-14 18:55 ` Johannes Weiner
2018-05-14 20:15 ` Christopher Lameter
2018-05-26 0:29 ` Suren Baghdasaryan
2018-05-29 18:16 ` Johannes Weiner
2018-05-30 23:32 ` Suren Baghdasaryan
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