From: Vladimir Davydov <vdavydov@parallels.com>
To: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Minchan Kim <minchan@kernel.org>,
Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@suse.cz>, Greg Thelen <gthelen@google.com>,
Michel Lespinasse <walken@google.com>,
David Rientjes <rientjes@google.com>,
Pavel Emelyanov <xemul@parallels.com>,
Cyrill Gorcunov <gorcunov@openvz.org>,
Jonathan Corbet <corbet@lwn.net>,
linux-api@vger.kernel.org, linux-doc@vger.kernel.org,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH -mm v8 4/7] proc: add kpagecgroup file
Date: Thu, 16 Jul 2015 12:28:41 +0300 [thread overview]
Message-ID: <20150716092841.GA2001@esperanza> (raw)
In-Reply-To: <CAJu=L58kZW2WRpx8wLx=FXdS29BJ+euLRdDcTXJKwf-VLT6SCA@mail.gmail.com>
On Wed, Jul 15, 2015 at 12:03:18PM -0700, Andres Lagar-Cavilla wrote:
> For both /proc/kpage* interfaces you add (and more critically for the
> rmap-causing one, kpageidle):
>
> It's a good idea to do cond_sched(). Whether after each pfn, each Nth
> pfn, each put_user, I leave to you, but a reasonable cadence is
> needed, because user-space can call this on the entire physical
> address space, and that's a lot of work to do without re-scheduling.
I really don't think it's necessary. These files can only be
read/written by the root, who has plenty ways to kill the system anyway.
The program that is allowed to read/write these files must be conscious
and do it in batches of reasonable size. AFAICS the same reasoning
already lays behind /proc/kpagecount and /proc/kpageflag, which also do
not thrust the "right" batch size on their readers.
Thanks,
Vladimir
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next prev parent reply other threads:[~2015-07-16 9:28 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-15 13:54 [PATCH -mm v8 0/7] idle memory tracking Vladimir Davydov
2015-07-15 13:54 ` [PATCH -mm v8 1/7] memcg: add page_cgroup_ino helper Vladimir Davydov
2015-07-15 18:59 ` Andres Lagar-Cavilla
2015-07-15 13:54 ` [PATCH -mm v8 2/7] hwpoison: use page_cgroup_ino for filtering by memcg Vladimir Davydov
2015-07-15 19:00 ` Andres Lagar-Cavilla
2015-07-15 13:54 ` [PATCH -mm v8 3/7] memcg: zap try_get_mem_cgroup_from_page Vladimir Davydov
2015-07-15 13:54 ` [PATCH -mm v8 4/7] proc: add kpagecgroup file Vladimir Davydov
2015-07-15 19:03 ` Andres Lagar-Cavilla
2015-07-16 9:28 ` Vladimir Davydov [this message]
2015-07-16 19:04 ` Andres Lagar-Cavilla
2015-07-17 9:27 ` Vladimir Davydov
2015-07-15 13:54 ` [PATCH -mm v8 5/7] mmu-notifier: add clear_young callback Vladimir Davydov
2015-07-15 19:16 ` Andres Lagar-Cavilla
2015-07-16 11:35 ` Paolo Bonzini
2015-07-15 13:54 ` [PATCH -mm v8 6/7] proc: add kpageidle file Vladimir Davydov
2015-07-15 19:42 ` Andres Lagar-Cavilla
2015-07-16 9:53 ` Vladimir Davydov
2015-07-15 13:54 ` [PATCH -mm v8 7/7] proc: export idle flag via kpageflags Vladimir Davydov
2015-07-15 19:17 ` Andres Lagar-Cavilla
2015-07-15 20:47 ` [PATCH -mm v8 0/7] idle memory tracking Andres Lagar-Cavilla
2015-07-16 10:02 ` Vladimir Davydov
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