diff options
author | Shaohua Li <shli@fb.com> | 2015-06-11 16:50:48 -0700 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-07-10 10:37:56 -0700 |
commit | 00764c5282e8320c4938ed732d4d1df189880316 (patch) | |
tree | da32b61e7d20ce7d5d89223cd1a050fa1372540f /include | |
parent | 1a3c14f438f91748cc2b2b51250e842a31920bfd (diff) |
net: don't wait for order-3 page allocation
[ Upstream commit fb05e7a89f500cfc06ae277bdc911b281928995d ]
We saw excessive direct memory compaction triggered by skb_page_frag_refill.
This causes performance issues and add latency. Commit 5640f7685831e0
introduces the order-3 allocation. According to the changelog, the order-3
allocation isn't a must-have but to improve performance. But direct memory
compaction has high overhead. The benefit of order-3 allocation can't
compensate the overhead of direct memory compaction.
This patch makes the order-3 page allocation atomic. If there is no memory
pressure and memory isn't fragmented, the alloction will still success, so we
don't sacrifice the order-3 benefit here. If the atomic allocation fails,
direct memory compaction will not be triggered, skb_page_frag_refill will
fallback to order-0 immediately, hence the direct memory compaction overhead is
avoided. In the allocation failure case, kswapd is waken up and doing
compaction, so chances are allocation could success next time.
alloc_skb_with_frags is the same.
The mellanox driver does similar thing, if this is accepted, we must fix
the driver too.
V3: fix the same issue in alloc_skb_with_frags as pointed out by Eric
V2: make the changelog clearer
Cc: Eric Dumazet <edumazet@google.com>
Cc: Chris Mason <clm@fb.com>
Cc: Debabrata Banerjee <dbavatar@gmail.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
0 files changed, 0 insertions, 0 deletions