netdev - Re: [PATCH v2] net: use bulk free in kfree_skb

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Date:   Mon, 25 Mar 2019 02:31:29 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Felix Fietkau <nbd@....name>, netdev@...r.kernel.org
Cc:     davem@...emloft.net, brouer@...hat.com, fw@...len.de
Subject: Re: [PATCH v2] net: use bulk free in kfree_skb_list



On 03/25/2019 02:09 AM, Felix Fietkau wrote:
> On 2019-03-25 09:51, Eric Dumazet wrote:
>>
>>
>> On 03/24/2019 09:56 AM, Felix Fietkau wrote:
>>> Since we're freeing multiple skbs, we might as well use bulk free to save a
>>> few cycles. Use the same conditions for bulk free as in napi_consume_skb.
>>>
>>
>> I do not believe kfree_skb_list() is used in the fast path, so do we really
>> need to make it so complex ?
> mac80211 uses it to free the fraglist from A-MSDU aggregated packets in
> the tx status path. That's one fast path where it gets used right now
> and the reason it was showing up in my perf traces.

This is not drop monitor friendly then....

TX completion should use consume_skb() or dev_kfree_skb()

BTW, I wonder what drop-monitor signal bulk free is sending ?