From: Dan Schatzberg <schatzberg.dan@gmail.com>
To: "Michal Koutný" <mkoutny@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"open list:BLOCK LAYER" <linux-block@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>,
"open list:CONTROL GROUP (CGROUP)" <cgroups@vger.kernel.org>,
"open list:MEMORY MANAGEMENT" <linux-mm@kvack.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH 3/3] loop: Charge i/o to mem and blk cg
Date: Mon, 28 Jun 2021 10:17:18 -0400 [thread overview]
Message-ID: <YNnZ7hIRIk9dJDry@dschatzberg-fedora-PC0Y6AEN> (raw)
In-Reply-To: <YNXvr81YFzbaTxCb@blackbook>
Hi Michal,
On Fri, Jun 25, 2021 at 05:01:03PM +0200, Michal Koutný wrote:
> Hi.
>
> On Thu, Jun 10, 2021 at 10:39:44AM -0700, Dan Schatzberg <schatzberg.dan@gmail.com> wrote:
> > The current code only associates with the existing blkcg when aio is
> > used to access the backing file. This patch covers all types of i/o to
> > the backing file and also associates the memcg so if the backing file is
> > on tmpfs, memory is charged appropriately.
> >
> > This patch also exports cgroup_get_e_css and int_active_memcg so it
> > can be used by the loop module.
>
> Wouldn't it be clearer to export (not explicitly inlined anymore)
> set_active_memcg() instead of the int_active_memcg that's rather an
> implementation detail?
Agreed that exporting int_active_memcg is an implementation detail,
but would this prevent set_active_memcg from being inlined? Is that
desireable?
>
> > @@ -2111,13 +2112,18 @@ static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,
> > }
> >
> > /* always use the first bio's css */
> > + cmd->blkcg_css = NULL;
> > + cmd->memcg_css = NULL;
> > #ifdef CONFIG_BLK_CGROUP
> > - if (cmd->use_aio && rq->bio && rq->bio->bi_blkg) {
> > - cmd->css = &bio_blkcg(rq->bio)->css;
> > - css_get(cmd->css);
> > - } else
> > + if (rq->bio && rq->bio->bi_blkg) {
> > + cmd->blkcg_css = &bio_blkcg(rq->bio)->css;
> > +#ifdef CONFIG_MEMCG
> > + cmd->memcg_css =
> > + cgroup_get_e_css(cmd->blkcg_css->cgroup,
> > + &memory_cgrp_subsys);
> > +#endif
> > + }
> > #endif
> > - cmd->css = NULL;
> > loop_queue_work(lo, cmd);
>
> I see you dropped the cmd->blkcg_css reference (while rq is handled). Is
> it intentional?
Yes it is intentional. All requests (not just aio) go through the loop
worker which grabs the blkcg reference in loop_queue_work() on
construction. So I believe grabbing a reference per request is
unnecessary.
next prev parent reply other threads:[~2021-06-28 14:17 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-10 17:39 [PATCH V14 0/3] Charge loop device i/o to issuing cgroup Dan Schatzberg
2021-06-10 17:39 ` [PATCH 1/3] loop: Use worker per cgroup instead of kworker Dan Schatzberg
2021-06-10 17:39 ` [PATCH 2/3] mm: Charge active memcg when no mm is set Dan Schatzberg
2021-06-25 14:47 ` Michal Koutný
2021-06-10 17:39 ` [PATCH 3/3] loop: Charge i/o to mem and blk cg Dan Schatzberg
2021-06-25 15:01 ` Michal Koutný
2021-06-28 14:17 ` Dan Schatzberg [this message]
2021-06-29 10:26 ` Michal Koutný
2021-06-29 14:03 ` Dan Schatzberg
2021-06-30 9:42 ` Michal Koutný
2021-06-30 14:49 ` Dan Schatzberg
-- strict thread matches above, loose matches on Subject: below --
2021-06-03 14:57 [PATCH V13 0/3] Charge loop device i/o to issuing cgroup Dan Schatzberg
2021-06-03 14:57 ` [PATCH 3/3] loop: Charge i/o to mem and blk cg Dan Schatzberg
2021-04-02 19:16 [PATCH V12 0/3] Charge loop device i/o to issuing cgroup Dan Schatzberg
2021-04-02 19:16 ` [PATCH 3/3] loop: Charge i/o to mem and blk cg Dan Schatzberg
2021-04-06 3:23 ` Ming Lei
2021-03-29 14:48 [PATCH V11 0/3] Charge loop device i/o to issuing cgroup Dan Schatzberg
2021-03-29 14:48 ` [PATCH 3/3] loop: Charge i/o to mem and blk cg Dan Schatzberg
2021-03-16 15:36 [PATCH v10 0/3] Charge loop device i/o to issuing cgroup Dan Schatzberg
2021-03-16 15:36 ` [PATCH 3/3] loop: Charge i/o to mem and blk cg Dan Schatzberg
2021-03-16 16:25 ` Shakeel Butt
2020-08-31 15:36 [PATCH v8 0/3] Charge loop device i/o to issuing cgroup Dan Schatzberg
2020-08-31 15:37 ` [PATCH 3/3] loop: Charge i/o to mem and blk cg Dan Schatzberg
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