From: Nathan Lynch <nathanl@linux.ibm.com>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
Nicholas Piggin <npiggin@gmail.com>
Subject: Re: [PATCH v2 3/4] powerpc/numa: Early request for home node associativity
Date: Fri, 06 Sep 2019 16:34:58 -0500 [thread overview]
Message-ID: <87r24tqfb1.fsf@linux.ibm.com> (raw)
In-Reply-To: <20190906034110.GA12412@linux.vnet.ibm.com>
Srikar Dronamraju <srikar@linux.vnet.ibm.com> writes:
>> Regardless, I have an annoying question :-) Isn't it possible that,
>> while Linux is calling vphn_get_nid() for each logical cpu in sequence,
>> the platform could change a virtual processor's node assignment,
>> potentially causing sibling threads to get different node assignments
>> and producing an incoherent topology (which then leads to sched domain
>> assertions etc)?
>>
>
> Right, its certainly possible for node assignment to change while we iterate
> through the siblings. Do you have an recommendations?
>
>> If so, I think more care is needed. The algorithm should make the vphn
>> call only once per cpu node, I think?
>
> I didn't get "once per cpu node", How do we know which all cpus are part of
> that cpu node? Or did you mean once per cpu core?
Sorry, "node" is overloaded in this context. I meant once per cpu
device node from the device tree, each of which I believe corresponds to
a core, yes.
next prev parent reply other threads:[~2019-09-06 21:37 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-29 5:50 [PATCH v2 0/4] Early node associativity Srikar Dronamraju
2019-08-29 5:50 ` [PATCH v2 1/4] powerpc/vphn: Check for error from hcall_vphn Srikar Dronamraju
2019-08-29 5:50 ` [PATCH v2 2/4] powerpc/numa: Handle extra hcall_vphn error cases Srikar Dronamraju
2019-08-29 5:50 ` [PATCH v2 3/4] powerpc/numa: Early request for home node associativity Srikar Dronamraju
2019-09-05 20:04 ` Nathan Lynch
2019-09-06 3:41 ` Srikar Dronamraju
2019-09-06 13:49 ` Srikar Dronamraju
2019-09-06 21:34 ` Nathan Lynch [this message]
2019-08-29 5:50 ` [PATCH v2 4/4] powerpc/numa: Remove late " Srikar Dronamraju
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