netdev - Re: [PATCH 0/5] Beginnings of skb_frag -> bio

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Message-ID: <639880c6-5703-857c-8a70-82fbb5a90238@gmail.com>
Date:   Wed, 1 May 2019 04:14:41 -0400
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Matthew Wilcox <willy@...radead.org>, davem@...emloft.net
Cc:     hch@....de, netdev@...r.kernel.org
Subject: Re: [PATCH 0/5] Beginnings of skb_frag -> bio_vec conversion



On 4/30/19 9:17 PM, Matthew Wilcox wrote:
> From: "Matthew Wilcox (Oracle)" <willy@...radead.org>
> 
> It turns out there's a lot of accessors for the skb_frag, which would
> make this conversion really easy if some drivers didn't bypass them.
> This is what I've done so far; my laptop's not really beefy enough to
> cope with changing skbuff.h too often ;-)
> 
> This would be a great time to tell me I'm going about this all wrong.
> I already found one problem in this patch set; some of the drivers should
> have been converted to skb_frag_dma_map() instead of fixing the arguments
> to dma_map_page().  But anyway, I need sleep.
> 

I guess the missing part here is the "why" all this is done ?

32 bit hosts will have bigger skb_shared_info and this impacts sk_rcvbuf and sk_sndbuf limits.

17 * 4 are 68 extra bytes per skb.