From: Shaohua Li <s...@fb.com> 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 <eduma...@google.com> Cc: Chris Mason <c...@fb.com> Cc: Debabrata Banerjee <dbava...@gmail.com> Signed-off-by: Shaohua Li <s...@fb.com> Acked-by: Eric Dumazet <eduma...@google.com> Signed-off-by: David S. Miller <da...@davemloft.net> https://jira.sw.ru/browse/PSBM-81488 (cherry picked from commit fb05e7a89f500cfc06ae277bdc911b281928995d) Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com> --- net/core/skbuff.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 4147d7219589..dca9d1d9676b 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4360,7 +4360,7 @@ 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) | __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY, -- 2.13.6 _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel
