Re: [PATCH ipsec-next v12 14/16] xfrm: iptfs: add skb-fragment sharing code

[Christian Hopps <chopps@chopps.org>]

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Steffen Klassert <steffen.klassert@secunet.com> writes:

> On Mon, Oct 07, 2024 at 09:59:26AM -0400, Christian Hopps wrote:
>> From: Christian Hopps <chopps@labn.net>
>>
>> Avoid copying the inner packet data by sharing the skb data fragments
>> from the output packet skb into new inner packet skb.
>>
>> Signed-off-by: Christian Hopps <chopps@labn.net>
>> ---
>>  net/xfrm/xfrm_iptfs.c | 312 ++++++++++++++++++++++++++++++++++++++++--
>>  1 file changed, 304 insertions(+), 8 deletions(-)
>>
>> diff --git a/net/xfrm/xfrm_iptfs.c b/net/xfrm/xfrm_iptfs.c
>> index 4c95656d7492..ef4c23159471 100644
>> --- a/net/xfrm/xfrm_iptfs.c
>> +++ b/net/xfrm/xfrm_iptfs.c
>> @@ -81,6 +81,9 @@
>>  #define XFRM_IPTFS_MIN_L3HEADROOM 128
>>  #define XFRM_IPTFS_MIN_L2HEADROOM (L1_CACHE_BYTES > 64 ? 64 : 64 + 16)
>>
>> +/* Min to try to share outer iptfs skb data vs copying into new skb */
>> +#define IPTFS_PKT_SHARE_MIN 129
>> +
>>  #define NSECS_IN_USEC 1000
>>
>>  #define IPTFS_HRTIMER_MODE HRTIMER_MODE_REL_SOFT
>> @@ -236,10 +239,261 @@ static void iptfs_skb_head_to_frag(const struct sk_buff *skb, skb_frag_t *frag)
>>  	skb_frag_fill_page_desc(frag, page, skb->data - addr, skb_headlen(skb));
>>  }
>>
>> +/**
>> + * struct iptfs_skb_frag_walk - use to track a walk through fragments
>> + * @fragi: current fragment index
>> + * @past: length of data in fragments before @fragi
>> + * @total: length of data in all fragments
>> + * @nr_frags: number of fragments present in array
>> + * @initial_offset: the value passed in to skb_prepare_frag_walk()
>> + * @pp_recycle: copy of skb->pp_recycle
>> + * @frags: the page fragments inc. room for head page
>> + */
>> +struct iptfs_skb_frag_walk {
>> +	u32 fragi;
>> +	u32 past;
>> +	u32 total;
>> +	u32 nr_frags;
>> +	u32 initial_offset;
>> +	bool pp_recycle;
>
> This boll creates a 3 byte hole. Better to put it to the end.

Moved.

Thanks,
Chris.

>> +	skb_frag_t frags[MAX_SKB_FRAGS + 1];
>> +};

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