netdev - Re: [PATCH] net: skbuff: allocate the fclone in the current NUMA node

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Date: Tue, 20 Feb 2024 16:37:18 +0800
From: Shijie Huang <shijie@...eremail.onmicrosoft.com>
To: Eric Dumazet <edumazet@...gle.com>
Cc: Huang Shijie <shijie@...amperecomputing.com>, kuba@...nel.org,
 patches@...erecomputing.com, davem@...emloft.net, horms@...nel.org,
 ast@...nel.org, dhowells@...hat.com, linyunsheng@...wei.com,
 aleksander.lobakin@...el.com, linux-kernel@...r.kernel.org,
 netdev@...r.kernel.org, cl@...amperecomputing.com
Subject: Re: [PATCH] net: skbuff: allocate the fclone in the current NUMA node


在 2024/2/20 16:17, Eric Dumazet 写道:
> On Tue, Feb 20, 2024 at 7:26 AM Shijie Huang
> <shijie@...eremail.onmicrosoft.com> wrote:
>>
>> 在 2024/2/20 13:32, Eric Dumazet 写道:
>>> On Tue, Feb 20, 2024 at 3:18 AM Huang Shijie
>>> <shijie@...amperecomputing.com> wrote:
>>>> The current code passes NUMA_NO_NODE to __alloc_skb(), we found
>>>> it may creates fclone SKB in remote NUMA node.
>>> This is intended (WAI)
>> Okay. thanks a lot.
>>
>> It seems I should fix the issue in other code, not the networking.
>>
>>> What about the NUMA policies of the current thread ?
>> We use "numactl -m 0" for memcached, the NUMA policy should allocate
>> fclone in
>>
>> node 0, but we can see many fclones were allocated in node 1.
>>
>> We have enough memory to allocate these fclones in node 0.
>>
>>> Has NUMA_NO_NODE behavior changed recently?
>> I guess not.
>>> What means : "it may creates" ? Please be more specific.
>> When we use the memcached for testing in NUMA, there are maybe 20% ~ 30%
>> fclones were allocated in
>>
>> remote NUMA node.
> Interesting, how was it measured exactly ?

I created a private patch to record the status for each fclone allocation.


> Are you using SLUB or SLAB ?

I think I use SLUB. (CONFIG_SLUB=y, 
CONFIG_SLAB_MERGE_DEFAULT=y,CONFIG_SLUB_CPU_PARTIAL=y)


Thanks

Huang Shijie