linux-kernel - Re: [PATCH 2/2] mm, memory_hotplug: remove timeout from __offline

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Message-ID: <59AD174B.4020807@huawei.com>
Date:   Mon, 4 Sep 2017 17:05:15 +0800
From:   Xishi Qiu <qiuxishi@...wei.com>
To:     Michal Hocko <mhocko@...nel.org>
CC:     Andrew Morton <akpm@...ux-foundation.org>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
        Reza Arbab <arbab@...ux.vnet.ibm.com>,
        Yasuaki Ishimatsu <yasu.isimatu@...il.com>,
        Igor Mammedov <imammedo@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>, <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] mm, memory_hotplug: remove timeout from __offline_memory

On 2017/9/4 17:01, Michal Hocko wrote:

> On Mon 04-09-17 16:58:30, Xishi Qiu wrote:
>> On 2017/9/4 16:21, Michal Hocko wrote:
>>
>>> From: Michal Hocko <mhocko@...e.com>
>>>
>>> We have a hardcoded 120s timeout after which the memory offline fails
>>> basically since the hot remove has been introduced. This is essentially
>>> a policy implemented in the kernel. Moreover there is no way to adjust
>>> the timeout and so we are sometimes facing memory offline failures if
>>> the system is under a heavy memory pressure or very intensive CPU
>>> workload on large machines.
>>>
>>> It is not very clear what purpose the timeout actually serves. The
>>> offline operation is interruptible by a signal so if userspace wants
>>
>> Hi Michal,
>>
>> If the user know what he should do if migration for a long time,
>> it is OK, but I don't think all the users know this operation
>> (e.g. ctrl + c) and the affect.
> 
> How is this operation any different from other potentially long
> interruptible syscalls?
> 

Hi Michal,

I means the user should stop it by himself if migration always retry in endless.

Thanks,
Xishi Qiu