linux-kernel - Re: [PATCH v2 0/1] pseries/hotplug: Change the default behaviour of cede

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Message-ID: <20191029111314.GC12266@in.ibm.com>
Date:   Tue, 29 Oct 2019 16:43:14 +0530
From:   Gautham R Shenoy <ego@...ux.vnet.ibm.com>
To:     Nathan Lynch <nathanl@...ux.ibm.com>
Cc:     "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        Tyrel Datwyler <tyreld@...ux.ibm.com>,
        Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
        Kamalesh Babulal <kamaleshb@...ibm.com>,
        "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>
Subject: Re: [PATCH v2 0/1] pseries/hotplug: Change the default behaviour of
 cede_offline

Hello Nathan,


On Fri, Oct 25, 2019 at 06:03:26PM -0500, Nathan Lynch wrote:
> "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com> writes:
> > This is the v2 of the fix to change the default behaviour of
> > cede_offline.
> 
> OK, but why keep the cede offline behavior at all? Can we remove it? I
> think doing so would allow us to remove all the code that temporarily
> onlines threads for partition migration.

May be I am missing something. But don't we want all the CPUs to come
online and execute the H_JOIN hcall before performing partition
migration? How will this change whether the offlined CPUs are in
H_CEDE or rtas-stop-self?

--
Thanks and Regards
gautham.