Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932768AbbG1JvE (ORCPT ); Tue, 28 Jul 2015 05:51:04 -0400 Received: from mail-wi0-f180.google.com ([209.85.212.180]:34281 "EHLO mail-wi0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755403AbbG1Jpp (ORCPT ); Tue, 28 Jul 2015 05:45:45 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Shaohua Li , Eric Dumazet , Chris Mason , Debabrata Banerjee , "David S. Miller" , Jiri Slaby Subject: [PATCH 3.12 078/124] net: don't wait for order-3 page allocation Date: Tue, 28 Jul 2015 11:43:32 +0200 Message-Id: <6088661c5342f33e3d667e866339b85ff985934b.1438076484.git.jslaby@suse.cz> X-Mailer: git-send-email 2.4.6 In-Reply-To: <90d8a5681e4a9e320611b422f0ed012e148c2bca.1438076484.git.jslaby@suse.cz> References: <90d8a5681e4a9e320611b422f0ed012e148c2bca.1438076484.git.jslaby@suse.cz> In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2950 Lines: 84 From: Shaohua Li 3.12-stable review patch. If anyone has any objections, please let me know. =============== [ 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 Cc: Chris Mason Cc: Debabrata Banerjee Signed-off-by: Shaohua Li Acked-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Jiri Slaby --- net/core/skbuff.c | 4 +++- net/core/sock.c | 4 +++- 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index fa8448a730a9..b01dd5f421da 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -367,9 +367,11 @@ refill: for (order = NETDEV_FRAG_PAGE_MAX_ORDER; ;) { gfp_t gfp = gfp_mask; - if (order) + if (order) { gfp |= __GFP_COMP | __GFP_NOWARN | __GFP_NOMEMALLOC; + gfp &= ~__GFP_WAIT; + } nc->frag.page = alloc_pages(gfp, order); if (likely(nc->frag.page)) break; diff --git a/net/core/sock.c b/net/core/sock.c index f9ec2f5be1c0..2335a7a130f2 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1907,8 +1907,10 @@ bool sk_page_frag_refill(struct sock *sk, struct page_frag *pfrag) do { gfp_t gfp = sk->sk_allocation; - if (order) + if (order) { gfp |= __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY; + gfp &= ~__GFP_WAIT; + } pfrag->page = alloc_pages(gfp, order); if (likely(pfrag->page)) { pfrag->offset = 0; -- 2.4.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/