From patchwork Fri Oct 29 06:28:14 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Xuan Zhuo X-Patchwork-Id: 12591833 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E3332C433FE for ; Fri, 29 Oct 2021 06:28:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BE66C6108F for ; Fri, 29 Oct 2021 06:28:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231985AbhJ2Gas (ORCPT ); Fri, 29 Oct 2021 02:30:48 -0400 Received: from out30-44.freemail.mail.aliyun.com ([115.124.30.44]:60623 "EHLO out30-44.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231992AbhJ2Gar (ORCPT ); Fri, 29 Oct 2021 02:30:47 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01424;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0Uu6GNe8_1635488895; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0Uu6GNe8_1635488895) by smtp.aliyun-inc.com(127.0.0.1); Fri, 29 Oct 2021 14:28:16 +0800 From: Xuan Zhuo To: virtualization@lists.linux-foundation.org, netdev@vger.kernel.org Cc: "Michael S. Tsirkin" , Jason Wang , "David S. Miller" , Jakub Kicinski Subject: [PATCH v3 3/3] virtio-net: enable virtio desc cache Date: Fri, 29 Oct 2021 14:28:14 +0800 Message-Id: <20211029062814.76594-4-xuanzhuo@linux.alibaba.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20211029062814.76594-1-xuanzhuo@linux.alibaba.com> References: <20211029062814.76594-1-xuanzhuo@linux.alibaba.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org If the VIRTIO_RING_F_INDIRECT_DESC negotiation succeeds, and the number of sgs used for sending packets is greater than 1. We must constantly call __kmalloc/kfree to allocate/release desc. In the case of extremely fast package delivery, the overhead cannot be ignored: 27.46% [kernel] [k] virtqueue_add 16.66% [kernel] [k] detach_buf_split 16.51% [kernel] [k] virtnet_xsk_xmit 14.04% [kernel] [k] virtqueue_add_outbuf > 5.18% [kernel] [k] __kmalloc > 4.08% [kernel] [k] kfree 2.80% [kernel] [k] virtqueue_get_buf_ctx 2.22% [kernel] [k] xsk_tx_peek_desc 2.08% [kernel] [k] memset_erms 0.83% [kernel] [k] virtqueue_kick_prepare 0.76% [kernel] [k] virtnet_xsk_run 0.62% [kernel] [k] __free_old_xmit_ptr 0.60% [kernel] [k] vring_map_one_sg 0.53% [kernel] [k] native_apic_mem_write 0.46% [kernel] [k] sg_next 0.43% [kernel] [k] sg_init_table > 0.41% [kernel] [k] kmalloc_slab Compared to not using virtio indirect cache, virtio-net can get a 16% performance improvement when using virtio desc cache. In the test case, the CPU where the package is sent has reached 100%. The following are the PPS in two cases: indirect desc cache | no cache 3074658 | 2685132 3111866 | 2666118 3152527 | 2653632 3125867 | 2669820 3027147 | 2644464 3069211 | 2669777 3038522 | 2675645 3034507 | 2671302 3102257 | 2685504 3083712 | 2692800 3051771 | 2676928 3080684 | 2695040 3147816 | 2720876 3123887 | 2705492 3180963 | 2699520 3191579 | 2676480 3161670 | 2686272 3189768 | 2692588 3174272 | 2686692 3143434 | 2682416 Signed-off-by: Xuan Zhuo --- drivers/net/virtio_net.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 4ad25a8b0870..df2514281847 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -31,6 +31,12 @@ module_param(csum, bool, 0444); module_param(gso, bool, 0444); module_param(napi_tx, bool, 0644); +/* Because virtio desc cache will increase memory overhead, users can turn it + * off or select an acceptable value. The maximum value is 2 + MAX_SKB_FRAGS. + */ +static u32 virtio_desc_cache_thr = 4; +module_param(virtio_desc_cache_thr, uint, 0644); + /* FIXME: MTU in config. */ #define GOOD_PACKET_LEN (ETH_HLEN + VLAN_HLEN + ETH_DATA_LEN) #define GOOD_COPY_LEN 128 @@ -3214,6 +3220,11 @@ static int virtnet_probe(struct virtio_device *vdev) vi->curr_queue_pairs = num_online_cpus(); vi->max_queue_pairs = max_queue_pairs; + if (virtio_desc_cache_thr > 2 + MAX_SKB_FRAGS) + virtio_set_desc_cache(vdev, 2 + MAX_SKB_FRAGS); + else + virtio_set_desc_cache(vdev, virtio_desc_cache_thr); + /* Allocate/initialize the rx/tx queues, and invoke find_vqs */ err = init_vqs(vi); if (err)