From: Alexander Duyck <alexander.duyck@gmail.com>
To: Vlastimil Babka <vbabka@suse.cz>,
Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
dev@openvswitch.org, Pravin Shelar <pshelar@nicira.com>,
"David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] ovs: do not allocate memory from offline numa node
Date: Mon, 5 Oct 2015 13:25:44 -0700 [thread overview]
Message-ID: <5612DCC8.4040605@gmail.com> (raw)
In-Reply-To: <56128238.8010305@suse.cz>
On 10/05/2015 06:59 AM, Vlastimil Babka wrote:
> On 10/02/2015 12:18 PM, Konstantin Khlebnikov wrote:
>> When openvswitch tries allocate memory from offline numa node 0:
>> stats = kmem_cache_alloc_node(flow_stats_cache, GFP_KERNEL |
>> __GFP_ZERO, 0)
>> It catches VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES ||
>> !node_online(nid))
>> [ replaced with VM_WARN_ON(!node_online(nid)) recently ] in linux/gfp.h
>> This patch disables numa affinity in this case.
>>
>> Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
>
> ...
>
>> diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
>> index f2ea83ba4763..c7f74aab34b9 100644
>> --- a/net/openvswitch/flow_table.c
>> +++ b/net/openvswitch/flow_table.c
>> @@ -93,7 +93,8 @@ struct sw_flow *ovs_flow_alloc(void)
>>
>> /* Initialize the default stat node. */
>> stats = kmem_cache_alloc_node(flow_stats_cache,
>> - GFP_KERNEL | __GFP_ZERO, 0);
>> + GFP_KERNEL | __GFP_ZERO,
>> + node_online(0) ? 0 : NUMA_NO_NODE);
>
> Stupid question: can node 0 become offline between this check, and the
> VM_WARN_ON? :) BTW what kind of system has node 0 offline?
Another question to ask would be is it possible for node 0 to be online,
but be a memoryless node?
I would say you are better off just making this call kmem_cache_alloc.
I don't see anything that indicates the memory has to come from node 0,
so adding the extra overhead doesn't provide any value.
- Alex
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next prev parent reply other threads:[~2015-10-05 20:25 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-02 10:18 [PATCH] ovs: do not allocate memory from offline numa node Konstantin Khlebnikov
2015-10-02 22:38 ` Pravin Shelar
2015-10-05 13:44 ` David Miller
2015-10-05 13:59 ` Vlastimil Babka
2015-10-05 20:25 ` Alexander Duyck [this message]
2015-10-07 1:01 ` [ovs-dev] " Jesse Gross
2015-10-07 17:47 ` Jarno Rajahalme
2015-10-08 23:03 ` Jesse Gross
2015-10-09 15:54 ` Jarno Rajahalme
2015-10-09 22:11 ` Jesse Gross
2015-10-10 0:02 ` Jarno Rajahalme
2015-10-20 17:58 ` Jarno Rajahalme
2015-10-21 8:55 ` Vlastimil Babka
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