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 16:36:33 +0200
Message-ID: <906edd92-cda3-9e79-ebdd-29a944082b61@6wind.com> (raw)
In-Reply-To: <4a1d578d-30e3-88de-be02-34ee0dd41ad1@mayadata.io>

Le 05/08/2020 à 16:20, Nick Connolly a écrit :
[snip]
>>> Fixes: 2a96c88be83e ("mem: ease init in a docker container")
>> I'm wondering if the bug existed before this commit.
>>
>> Before this commit, it was:
>>         move_pages(getpid(), 1, &addr, NULL, &cur_socket_id, 0);
>>         if (cur_socket_id != socket_id) {
>>                 /* error */
>>
>> Isn't it possible to hit this error case if CONFIG_NUMA is unset in the kernel?
> I've just run the previous code to test this out and you are right that
> move_pages does indeed return -1 with errno set to ENOSYS, but nothing checks
> this so execution carries on and compares cur_socket_id (which will be unchanged
> from the zero initialization) with socket_id (which is presumably also zero),
> thus allowing the allocation to succeed!
I came to this conclusion, but I didn't check if socket_id could be != from 0.

>> [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?


Regards,
Nicolas

  reply	other threads:[~2020-08-05 14:36 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 [this message]
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
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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