Re: [PATCH 2/2] mm, memory_hotplug: remove timeout from __offline_memory

From	Michal Hocko <mhocko@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 2/2] mm, memory_hotplug: remove timeout from __offline_memory
Date	2017-09-04 11:20 +0200
Message-ID	<ulVHX-3EY-7@gated-at.bofh.it> (permalink)
References	<ulUVz-38W-9@gated-at.bofh.it> <ulUVz-38W-11@gated-at.bofh.it> <ulVoD-3is-21@gated-at.bofh.it> <ulVyi-3AK-17@gated-at.bofh.it> <ulVyi-3AK-15@gated-at.bofh.it>
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On Mon 04-09-17 17:05:15, Xishi Qiu wrote:
> 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@suse.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.

If the memory is migrateable then the migration should finish
eventually. It can take some time but it shouldn't be an endless loop.
-- 
Michal Hocko
SUSE Labs

Thread

[PATCH 2/2] mm, memory_hotplug: remove timeout from __offline_memory Michal Hocko <mhocko@kernel.org> - 2017-09-04 10:30 +0200
  Re: [PATCH 2/2] mm, memory_hotplug: remove timeout from __offline_memory Xishi Qiu <qiuxishi@huawei.com> - 2017-09-04 11:00 +0200
    Re: [PATCH 2/2] mm, memory_hotplug: remove timeout from __offline_memory Xishi Qiu <qiuxishi@huawei.com> - 2017-09-04 11:10 +0200
      Re: [PATCH 2/2] mm, memory_hotplug: remove timeout from  __offline_memory Michal Hocko <mhocko@kernel.org> - 2017-09-04 11:20 +0200
        Re: [PATCH 2/2] mm, memory_hotplug: remove timeout from  __offline_memory Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-09-05 07:50 +0200
          Re: [PATCH 2/2] mm, memory_hotplug: remove timeout from  __offline_memory Michal Hocko <mhocko@kernel.org> - 2017-09-05 09:30 +0200
            Re: [PATCH 2/2] mm, memory_hotplug: remove timeout from  __offline_memory Anshuman Khandual <khandual@linux.vnet.ibm.com> - 2017-09-05 11:00 +0200
    Re: [PATCH 2/2] mm, memory_hotplug: remove timeout from  __offline_memory Michal Hocko <mhocko@kernel.org> - 2017-09-04 11:10 +0200
  Re: [PATCH 2/2] mm, memory_hotplug: remove timeout from  __offline_memory Vlastimil Babka <vbabka@suse.cz> - 2017-09-08 19:30 +0200

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