path: root/net/core/skbuff.c
diff options
authorShaohua Li <>2015-06-11 16:50:48 -0700
committerDavid S. Miller <>2015-06-11 17:33:44 -0700
commitfb05e7a89f500cfc06ae277bdc911b281928995d (patch)
tree126cd57257dd5d24d11331ca286718c0f83afb5e /net/core/skbuff.c
parent0fae3bf018d97b210051c8797a49d66d31071847 (diff)
net: don't wait for order-3 page allocation
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 <> Cc: Chris Mason <> Cc: Debabrata Banerjee <> Signed-off-by: Shaohua Li <> Acked-by: Eric Dumazet <> Signed-off-by: David S. Miller <>
Diffstat (limited to 'net/core/skbuff.c')
1 files changed, 1 insertions, 1 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 3cfff2a3d651..41ec02242ea7 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -4398,7 +4398,7 @@ struct sk_buff *alloc_skb_with_frags(unsigned long header_len,
while (order) {
if (npages >= 1 << order) {
- page = alloc_pages(gfp_mask |
+ page = alloc_pages((gfp_mask & ~__GFP_WAIT) |