Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754012AbbGPBJ4 (ORCPT ); Wed, 15 Jul 2015 21:09:56 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:55128 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753931AbbGPBJu (ORCPT ); Wed, 15 Jul 2015 21:09:50 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Eric Dumazet , Chris Mason , Debabrata Banerjee , Shaohua Li , "David S. Miller" , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 001/251] net: don't wait for order-3 page allocation Date: Wed, 15 Jul 2015 18:05:22 -0700 Message-Id: <1437008972-9140-2-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1437008972-9140-1-git-send-email-kamal@canonical.com> References: <1437008972-9140-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2937 Lines: 77 3.19.8-ckt4 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Shaohua Li [ 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: Kamal Mostafa --- net/core/skbuff.c | 2 +- net/core/sock.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 3b0a8b0..0998af7 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4414,7 +4414,7 @@ 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, diff --git a/net/core/sock.c b/net/core/sock.c index a91f99f..3606cc5 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1888,7 +1888,7 @@ bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t gfp) pfrag->offset = 0; if (SKB_FRAG_PAGE_ORDER) { - pfrag->page = alloc_pages(gfp | __GFP_COMP | + pfrag->page = alloc_pages((gfp & ~__GFP_WAIT) | __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY, SKB_FRAG_PAGE_ORDER); if (likely(pfrag->page)) { -- 1.9.1 -- 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/