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| author | Wei Liu <wei.liu2@citrix.com> | 2013-09-22 20:03:44 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-10-01 01:14:11 +0200 |
| commit | 4f0581d25827d5e864bcf07b05d73d0d12a20a5c (patch) | |
| tree | 3fc6e6c5430c1e7cb1309e3250df727ca210e70c /net/ipv6/sysctl_net_ipv6.c | |
| parent | qdisc: basic classifier - remove unnecessary initialization (diff) | |
| download | linux-4f0581d25827d5e864bcf07b05d73d0d12a20a5c.tar.xz linux-4f0581d25827d5e864bcf07b05d73d0d12a20a5c.zip | |
xen-netback: improve ring effeciency for guest RX
There was a bug that netback routines netbk/xenvif_skb_count_slots and
netbk/xenvif_gop_frag_copy disagreed with each other, which caused
netback to push wrong number of responses to netfront, which caused
netfront to eventually crash. The bug was fixed in 6e43fc04a
("xen-netback: count number required slots for an skb more carefully").
Commit 6e43fc04a focused on backport-ability. The drawback with the
existing packing scheme is that the ring is not used effeciently, as
stated in 6e43fc04a.
skb->data like:
| 1111|222222222222|3333 |
is arranged as:
|1111 |222222222222|3333 |
If we can do this:
|111122222222|22223333 |
That would save one ring slot, which improves ring effeciency.
This patch effectively reverts 6e43fc04a. That patch made count_slots
agree with gop_frag_copy, while this patch goes the other way around --
make gop_frag_copy agree with count_slots. The end result is that they
still agree with each other, and the ring is now arranged like:
|111122222222|22223333 |
The patch that improves packing was first posted by Xi Xong and Matt
Wilson. I only rebase it on top of net-next and rewrite commit message,
so I retain all their SoBs. For more infomation about the original bug
please refer to email listed below and commit message of 6e43fc04a.
Original patch:
http://lists.xen.org/archives/html/xen-devel/2013-07/msg00760.html
Signed-off-by: Xi Xiong <xixiong@amazon.com>
Reviewed-by: Matt Wilson <msw@amazon.com>
[ msw: minor code cleanups, rewrote commit message, adjusted code
to count RX slots instead of meta structures ]
Signed-off-by: Matt Wilson <msw@amazon.com>
Cc: Annie Li <annie.li@oracle.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
[ liuw: rebased on top of net-next tree, rewrote commit message, coding
style cleanup. ]
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6/sysctl_net_ipv6.c')
0 files changed, 0 insertions, 0 deletions