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From: Michal Hocko <mhocko@suse.cz>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Vladimir Davydov <vdavydov@parallels.com>,
	Greg Thelen <gthelen@google.com>,
	linux-mm@kvack.org, cgroups@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [patch 2/2] mm: memcontrol: default hierarchy interface for memory
Date: Wed, 14 Jan 2015 17:17:47 +0100	[thread overview]
Message-ID: <20150114161747.GH4706@dhcp22.suse.cz> (raw)
In-Reply-To: <1420776904-8559-2-git-send-email-hannes@cmpxchg.org>

I have overlooked the `none' setting...

On Thu 08-01-15 23:15:04, Johannes Weiner wrote:
[...]
> +static int memory_low_show(struct seq_file *m, void *v)
> +{
> +	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
> +	unsigned long low = ACCESS_ONCE(memcg->low);
> +
> +	if (low == 0)
> +		seq_printf(m, "none\n");
> +	else
> +		seq_printf(m, "%llu\n", (u64)low * PAGE_SIZE);
> +
> +	return 0;
> +}

This is really confusing. What if somebody wants to protect a group
from being reclaimed? One possible and natural way would by copying
memory.max value but then `none' means something else completely.

Besides that why to call 0, which has a clear meaning, any other name?

Now that I think about the naming `none' doesn't sound that great for
max resp. high either. If for nothing else then for the above copy
example (who knows what shows up later). Sure, a huge number is bad
as well for reasons you have mentioned in other email. `resource_max'
sounds like a better fit to me. But I am lame at naming.
-- 
Michal Hocko
SUSE Labs

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  parent reply	other threads:[~2015-01-14 16:17 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-09  4:15 [patch 1/2] mm: page_counter: pull "-1" handling out of page_counter_memparse() Johannes Weiner
2015-01-09  4:15 ` [patch 2/2] mm: memcontrol: default hierarchy interface for memory Johannes Weiner
2015-01-12 23:37   ` Andrew Morton
2015-01-13 15:50     ` Johannes Weiner
2015-01-13 20:52       ` Andrew Morton
2015-01-13 21:44         ` Johannes Weiner
2015-01-13 23:20   ` Greg Thelen
2015-01-14 16:01     ` Johannes Weiner
2015-01-14 14:28   ` Vladimir Davydov
2015-01-14 15:34   ` Michal Hocko
2015-01-14 17:19     ` Johannes Weiner
2015-01-15 17:08       ` Michal Hocko
2015-01-14 16:17   ` Michal Hocko [this message]
2015-01-13 15:59 ` [patch 1/2] mm: page_counter: pull "-1" handling out of page_counter_memparse() Vladimir Davydov
2015-01-20 15:31 [patch 0/2] mm: memcontrol: default hierarchy interface for memory v2 Johannes Weiner
2015-01-20 15:31 ` [patch 2/2] mm: memcontrol: default hierarchy interface for memory Johannes Weiner
2015-01-20 16:31   ` Michal Hocko
2015-02-23 11:13   ` Sasha Levin
2015-02-23 14:28     ` Michal Hocko

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