patches for DPDK stable branches
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From: Nicolas Dichtel <nicolas.dichtel@6wind.com>
To: Nick Connolly <nick.connolly@mayadata.io>,
	Anatoly Burakov <anatoly.burakov@intel.com>
Cc: dev@dpdk.org, stable@dpdk.org
Subject: Re: [dpdk-stable] [PATCH] mem: fix allocation failure on non-NUMA kernel
Date: Wed, 5 Aug 2020 17:13:37 +0200
Message-ID: <e79e24fd-9028-1ba3-aa36-9c51cfe95ce3@6wind.com> (raw)
In-Reply-To: <e960495c-fc4d-3fb9-8d30-ad12f3047994@mayadata.io>

Le 05/08/2020 à 16:53, Nick Connolly a écrit :
[snip]
>>>>> +    if (check_numa()) {
>>>>> +        ret = get_mempolicy(&cur_socket_id, NULL, 0, addr,
>>>>> +                    MPOL_F_NODE | MPOL_F_ADDR);
>>>>> +        if (ret < 0) {
>>>>> +            RTE_LOG(DEBUG, EAL, "%s(): get_mempolicy: %s\n",
>>>>> +                __func__, strerror(errno));
>>>>> +            goto mapped;
>>>>> +        } else if (cur_socket_id != socket_id) {
>>>>> +            RTE_LOG(DEBUG, EAL,
>>>>> +                    "%s(): allocation happened on wrong socket (wanted %d,
>>>>> got %d)\n",
>>>>> +                __func__, socket_id, cur_socket_id);
>>>>> +            goto mapped;
>>>>> +        }
>>>>> +    } else {
>>>>> +        if (rte_socket_count() > 1)
>>>>> +            RTE_LOG(DEBUG, EAL, "%s(): not checking socket for allocation
>>>>> (wanted %d)\n",
>>>>> +                    __func__, socket_id);
>>>> nit: maybe an higher log level like WARNING?
>>> Open to guidance here - my concern was that this is going to be generated for
>>> every call to alloc_seg() and I'm not sure what the frequency will be - I'm
>>> cautious about flooding the log with warnings under 'normal running'.  Are the
>>> implications of running on a multi socket system with NUMA support disabled in
>>> the kernel purely performance related for the DPDK or is there a functional
>>> correctness issue as well?
>> Is it really a 'normal running' to have CONFIG_RTE_EAL_NUMA_AWARE_HUGEPAGES in
>> dpdk and not CONFIG_NUMA in the kernel?
> 
> I'm not an expert of DPDK, but I think it needs to be treated as 'normal
> running', for the following reasons:
> 
> 1. The existing code in eal_memalloc_alloc_seg_bulk() is designed to
>    work even if check_numa() indicates that NUMA support is not enabled:
> 
>    #ifdef RTE_EAL_NUMA_AWARE_HUGEPAGES
>    if (check_numa()) {
>             oldmask = numa_allocate_nodemask();
>             prepare_numa(&oldpolicy, oldmask, socket);
>             have_numa = true;
>         }
>    #endif
The question was not to return an error, but to display a warning. So the code
will work (after your patch), no problem.

> 2. The DPDK application could be built with
>    CONFIG_RTE_EAL_NUMA_AWARE_HUGE_PAGES and then the binary run on
>    different systems with and without NUMA support.
In a production environment, it seems odd to have a custom kernel and a generic
dpdk app, it's why I propose the log level WARNING (or NOTICE maybe?).
I let other comment about this, I don't have a strong opinion.


Regards,
Nicolas

  reply	other threads:[~2020-08-05 15:13 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 [this message]
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
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-stable] [PATCH v2] " Nick Connolly
2020-10-13  7:59   ` Nicolas Dichtel
2020-10-13 12:01     ` David Marchand

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