From: Jason Xing <kerneljasonxing@xxxxxxxxx>
Date: Thu, 28 Aug 2025 08:38:42 +0800
> On Wed, Aug 27, 2025 at 10:33 PM Alexander Lobakin
> <aleksander.lobakin@xxxxxxxxx> wrote:
>>
>> From: Jason Xing <kerneljasonxing@xxxxxxxxx>
>> Date: Mon, 25 Aug 2025 21:53:38 +0800
>>
>>> From: Jason Xing <kernelxing@xxxxxxxxxxx>
>>>
>>> Support allocating and building skbs in batch.
>>
>> [...]
>>
>>> + base_len = max(NET_SKB_PAD, L1_CACHE_ALIGN(dev->needed_headroom));
>>> + if (!(dev->priv_flags & IFF_TX_SKB_NO_LINEAR))
>>> + base_len += dev->needed_tailroom;
>>> +
>>> + if (xs->skb_count >= nb_pkts)
>>> + goto build;
>>> +
>>> + if (xs->skb) {
>>> + i = 1;
>>> + xs->skb_count++;
>>> + }
>>> +
>>> + xs->skb_count += kmem_cache_alloc_bulk(net_hotdata.skbuff_cache,
>>> + gfp_mask, nb_pkts - xs->skb_count,
>>> + (void **)&skbs[xs->skb_count]);
>>
>> Have you tried napi_skb_cache_get_bulk()? Depending on the workload, it
>> may give better perf numbers.
>
> Sure, my initial try is using this interface. But later I want to see
> a standalone cache belonging to xsk. The whole xsk_alloc_batch_skb
> function I added is quite similar to napi_skb_cache_get_bulk(), to
> some extent.
>
> And if using napi_xxx(), we need a lock to avoid the race between this
> context and softirq context on the same core.
Are you saying this particular function is not run in the softirq
context? I thought all Tx is done in BH.
If it's not BH, then ignore my suggestion -- napi_skb_cache_get_bulk()
requires BH, that's true.
>
> Thanks,
> Jason
Thanks,
Olek
