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From: Rik van Riel <riel@redhat.com>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Li Zefan <lizefan@huawei.com>, Tejun Heo <tj@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH 2/2] show nohz_full cpus in sysfs
Date: Sat, 28 Mar 2015 12:15:56 -0400	[thread overview]
Message-ID: <5516D3BC.6030704@redhat.com> (raw)
In-Reply-To: <CAFTL4hxAMYZGjCuxMohBbmS8YPfHqO8sisSjUacQ=u-OF3DTfA@mail.gmail.com>

On 03/28/2015 12:02 PM, Frederic Weisbecker wrote:
> 2015-03-27 22:50 GMT+01:00  <riel@redhat.com>:
>> From: Rik van Riel <riel@redhat.com>
>>
>> Currently there is no way to query which CPUs are in nohz_full
>> mode from userspace.
> 
> Well you can watch dmesg | grep NO_HZ
> But surely sysfs is more convenient from an app.
> 
> I guess it's ok, as long as it's strictly Read Only. Here it seems to
> be the case. And it's not chmod'able, right?

I followed the other code for files in that directory.

Quick testing shows that the cpu info files in
/sys/devices/system/cpu are chmoddable, but writing
to them fails with -EIO because there is no function
set up to handle writes. So yeah, read only :)

-- 
All rights reversed

  reply	other threads:[~2015-03-28 16:16 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-27 21:50 [PATCH 0/2] show isolated & nohz_full cpus in sysfs riel
2015-03-27 21:50 ` [PATCH 1/2] show isolated " riel
2015-03-27 21:50 ` [PATCH 2/2] show nohz_full " riel
2015-03-28  4:18   ` Mike Galbraith
2015-03-28 13:35     ` Rik van Riel
2015-03-28 14:10       ` Mike Galbraith
2015-03-28 16:02   ` Frederic Weisbecker
2015-03-28 16:15     ` Rik van Riel [this message]
2015-03-28 18:06       ` Frederic Weisbecker
2015-04-24 19:24 [PATCH 0/2 resend] show isolated & " riel
2015-04-24 19:24 ` [PATCH 2/2] show " riel
2015-04-28 19:18   ` Chris Metcalf

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