From: Nick Connolly <nick.connolly@mayadata.io>
To: "Burakov, Anatoly" <anatoly.burakov@intel.com>
Cc: dev@dpdk.org, nicolas.dichtel@6wind.com, stable@dpdk.org
Subject: Re: [dpdk-dev] [PATCH] mem: fix allocation failure on non-NUMA kernel
Date: Thu, 17 Sep 2020 14:05:44 +0100 [thread overview]
Message-ID: <eba65564-e165-ddb0-e260-c8dbff4e675e@mayadata.io> (raw)
In-Reply-To: <a77d79ce-5f62-31f4-478e-a252d811f93f@intel.com>
Hi Anatoly,
Thanks. My recollection is that all of the NUMA configuration flags
were set to 'n'.
Regards,
Nick
On 17/09/2020 13:57, Burakov, Anatoly wrote:
> On 17-Sep-20 1:29 PM, Nick Connolly wrote:
>> Hi Anatoly,
>>
>> Thanks for the response. You are asking a good question - here's
>> what I know:
>>
>> The issue arose on a single socket system, running WSL2 (full Linux
>> kernel running as a lightweight VM under Windows).
>> The default kernel in this environment is built with CONFIG_NUMA=n
>> which means get_mempolicy() returns an error.
>> This causes the check to ensure that the allocated memory is
>> associated with the correct socket to fail.
>>
>> The change is to skip the allocation check if check_numa() indicates
>> that NUMA-aware memory is not supported.
>>
>> Researching the meaning of CONFIG_NUMA, I found
>> https://cateee.net/lkddb/web-lkddb/NUMA.html which says:
>>> Enable NUMA (Non-Uniform Memory Access) support.
>>> The kernel will try to allocate memory used by a CPU on the local
>>> memory controller of the CPU and add some more NUMA awareness to the
>>> kernel.
>>
>> Clearly CONFIG_NUMA enables memory awareness, but there's no
>> indication in the description whether information about the NUMA
>> physical architecture is 'hidden', or whether it is still exposed
>> through /sys/devices/system/node* (which is used by the rte
>> initialisation code to determine how many sockets there are).
>> Unfortunately, I don't have ready access to a multi-socket Linux
>> system that I can test this out on, so I took the conservative
>> approach that it may be possible to have CONFIG_NUMA disabled, but
>> the kernel still report more than one node, and coded the change to
>> generate a debug message if this occurs.
>>
>> Do you know whether CONFIG_NUMA turns off all knowledge about the
>> hardware architecture? If it does, then I agree that the test for
>> rte_socket_count() serves no purpose and should be removed.
>>
>
> I have a system with a custom compiled kernel, i can recompile it
> without this flag and test this. I'll report back with results :)
>
next prev parent reply other threads:[~2020-09-17 13:05 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-05 12:26 Nick Connolly
2020-08-05 13:42 ` Nicolas Dichtel
2020-08-05 14:20 ` Nick Connolly
2020-08-05 14:36 ` Nicolas Dichtel
2020-08-05 14:53 ` Nick Connolly
2020-08-05 15:13 ` Nicolas Dichtel
2020-08-05 15:21 ` Nick Connolly
2020-09-17 11:28 ` Burakov, Anatoly
2020-09-17 11:31 ` Burakov, Anatoly
2020-09-17 12:29 ` Nick Connolly
2020-09-17 12:57 ` Burakov, Anatoly
2020-09-17 13:05 ` Nick Connolly [this message]
2020-09-17 14:07 ` Burakov, Anatoly
2020-09-17 14:08 ` Nick Connolly
2020-09-17 14:18 ` Burakov, Anatoly
2020-09-17 14:19 ` Nick Connolly
2020-10-12 19:28 ` [dpdk-dev] [PATCH v2] " Nick Connolly
2020-10-13 7:59 ` Nicolas Dichtel
2020-10-13 12:01 ` David Marchand
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