From: David Miller <davem@davemloft.net>
To: rusty@rustcorp.com.au
Cc: virtualization@lists.linux-foundation.org,
herbert@gondor.apana.org.au, virtualization@lists.osdl.org,
netdev@vger.kernel.org
Subject: Re: [6/6] [VIRTIO] net: Allow receiving SG packets
Date: Mon, 21 Apr 2008 13:04:18 -0700 (PDT) [thread overview]
Message-ID: <20080421.130418.01258045.davem@davemloft.net> (raw)
In-Reply-To: <200804220506.16887.rusty@rustcorp.com.au>
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Tue, 22 Apr 2008 05:06:16 +1000
> I'm not sure what the right number is here. Say worst case is header which
> goes over a page boundary then MAX_SKB_FRAGS in the skb, but for some reason
> that already has a +2:
>
> /* To allow 64K frame to be packed as single skb without frag_list */
> #define MAX_SKB_FRAGS (65536/PAGE_SIZE + 2)
>
> Unless someone explains, I'll change the xmit sg to 2+MAX_SKB_FRAGS as well.
MAX_SKB_FRAGS + 1 is what you ought to need.
MAX_SKB_FRAGS is only accounting for the skb frag pages.
If you want to know how many segments skb->data might
consume as well, you have to add one.
skb->data is linear, therefore it's not possible to need
more than one scatterlist entry for it.
next prev parent reply other threads:[~2008-04-21 20:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20080418031257.GA17993@gondor.apana.org.au>
[not found] ` <20080418032142.GD18071@gondor.apana.org.au>
[not found] ` <20080418032427.GE18071@gondor.apana.org.au>
2008-04-21 19:06 ` [6/6] [VIRTIO] net: Allow receiving SG packets Rusty Russell
2008-04-21 20:04 ` David Miller [this message]
2008-04-22 1:13 ` Herbert Xu
2008-04-22 2:50 ` Rusty Russell
2008-04-22 2:55 ` David Miller
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20080421.130418.01258045.davem@davemloft.net \
--to=davem@davemloft.net \
--cc=herbert@gondor.apana.org.au \
--cc=netdev@vger.kernel.org \
--cc=rusty@rustcorp.com.au \
--cc=virtualization@lists.linux-foundation.org \
--cc=virtualization@lists.osdl.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).