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From: Peter Hurley <peter@hurleysoftware.com>
To: Lin Ming <minggr@gmail.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>,
	Greg KH <gregkh@linuxfoundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	lkp@01.org, Tejun Heo <tj@kernel.org>
Subject: Re: increased vmap_area_lock contentions on "n_tty: Move buffers into n_tty_data"
Date: Wed, 25 Sep 2013 07:30:40 -0400	[thread overview]
Message-ID: <5242C960.7050506@hurleysoftware.com> (raw)
In-Reply-To: <CAF1ivSbYg296oHhO0_UXwkos8Ui_1C93pUnXPzow4qLWyAa2kg@mail.gmail.com>

On 09/25/2013 05:04 AM, Lin Ming wrote:
> On Wed, Sep 18, 2013 at 8:22 AM, Peter Hurley <peter@hurleysoftware.com> wrote:
> [snip]
>>
>> Looking over vmalloc.c, the critical section footprint of the vmap_area_lock
>> could definitely be reduced (even nearly eliminated), but that's a project
>> for
>> another day :)
>
> Hi Peter,
>
> I also looked over vmallo.c, but didn't find obvious way to reduce the
> critical section footprint.
> Could you share some hints how to do this?

vmap_area_list is an RCU list.
get_vmalloc_info() doesn't need to take the vmap_area_lock at all.
Look at __purge_vmap_area_lazy() for a howto.

Regards,
Peter Hurley


  reply	other threads:[~2013-09-25 11:30 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-09-13  0:51 increased vmap_area_lock contentions on "n_tty: Move buffers into n_tty_data" Fengguang Wu
2013-09-13  1:09 ` Fengguang Wu
2013-09-17 15:34   ` Peter Hurley
2013-09-17 23:22     ` Fengguang Wu
2013-09-18  0:22       ` Peter Hurley
2013-09-25  9:04         ` Lin Ming
2013-09-25 11:30           ` Peter Hurley [this message]
2013-09-25 14:53             ` Lin Ming
2013-09-25 16:02             ` Lin Ming
2013-09-26  3:20               ` Andi Kleen
2013-09-26 11:52                 ` Peter Hurley
2013-09-26 15:32                   ` Andi Kleen
2013-09-26 17:22                     ` Peter Hurley
2013-09-26  7:33         ` Andrew Morton
2013-09-26 11:31           ` Peter Hurley
2013-09-26 15:04             ` Greg KH
2013-09-26 17:35               ` Peter Hurley
2013-09-26 18:05                 ` Andrew Morton
2013-09-26 21:42                   ` Peter Hurley
2013-09-26 21:58                     ` Andrew Morton
2013-09-26 22:21                       ` Peter Hurley
2013-09-18  0:49   ` Peter Hurley
2013-09-13  3:17 ` Greg KH
2013-09-13  3:38   ` Fengguang Wu
2013-09-13  3:44     ` Greg KH
2013-09-13  9:55       ` Peter Hurley
2013-09-13 12:34         ` Greg KH
2013-09-17  2:42     ` Peter Hurley
2013-09-17  2:56       ` Fengguang Wu

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