From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Rosato Subject: Re: Regression in throughput between kvm guests over virtual bridge Date: Mon, 18 Sep 2017 14:11:08 -0400 Message-ID: <7d444584-3854-ace2-008d-0fdef1c9cef4@linux.vnet.ibm.com> References: <4c7e2924-b10f-0e97-c388-c8809ecfdeeb@linux.vnet.ibm.com> <627d0c7a-dce5-3094-d5d4-c1507fcb8080@linux.vnet.ibm.com> <50891c14-3fc6-f519-8c03-07bdef3090f4@redhat.com> <15abafa1-6d58-cd85-668a-bf361a296f52@redhat.com> <7345a69d-5e47-7058-c72b-bdd0f3c69210@linux.vnet.ibm.com> <55f9173b-a419-98f0-2516-cbd57299ba5d@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: davem@davemloft.net, mst@redhat.com To: Jason Wang , netdev@vger.kernel.org Return-path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:47162 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753448AbdIRSLQ (ORCPT ); Mon, 18 Sep 2017 14:11:16 -0400 Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v8IIBFCk080383 for ; Mon, 18 Sep 2017 14:11:15 -0400 Received: from e18.ny.us.ibm.com (e18.ny.us.ibm.com [129.33.205.208]) by mx0a-001b2d01.pphosted.com with ESMTP id 2d2dup5uj2-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 18 Sep 2017 14:11:15 -0400 Received: from localhost by e18.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 18 Sep 2017 14:11:14 -0400 In-Reply-To: Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: On 09/18/2017 03:36 AM, Jason Wang wrote: > > > On 2017年09月18日 11:13, Jason Wang wrote: >> >> >> On 2017年09月16日 03:19, Matthew Rosato wrote: >>>> It looks like vhost is slowed down for some reason which leads to more >>>> idle time on 4.13+VHOST_RX_BATCH=1. Appreciated if you can collect the >>>> perf.diff on host, one for rx and one for tx. >>>> >>> perf data below for the associated vhost threads, baseline=4.12, >>> delta1=4.13, delta2=4.13+VHOST_RX_BATCH=1 >>> >>> Client vhost: >>> >>> 60.12% -11.11% -12.34% [kernel.vmlinux] [k] raw_copy_from_user >>> 13.76% -1.28% -0.74% [kernel.vmlinux] [k] get_page_from_freelist >>> 2.00% +3.69% +3.54% [kernel.vmlinux] [k] __wake_up_sync_key >>> 1.19% +0.60% +0.66% [kernel.vmlinux] [k] __alloc_pages_nodemask >>> 1.12% +0.76% +0.86% [kernel.vmlinux] [k] copy_page_from_iter >>> 1.09% +0.28% +0.35% [vhost] [k] vhost_get_vq_desc >>> 1.07% +0.31% +0.26% [kernel.vmlinux] [k] alloc_skb_with_frags >>> 0.94% +0.42% +0.65% [kernel.vmlinux] [k] alloc_pages_current >>> 0.91% -0.19% -0.18% [kernel.vmlinux] [k] memcpy >>> 0.88% +0.26% +0.30% [kernel.vmlinux] [k] __next_zones_zonelist >>> 0.85% +0.05% +0.12% [kernel.vmlinux] [k] iov_iter_advance >>> 0.79% +0.09% +0.19% [vhost] [k] __vhost_add_used_n >>> 0.74% [kernel.vmlinux] [k] get_task_policy.part.7 >>> 0.74% -0.01% -0.05% [kernel.vmlinux] [k] tun_net_xmit >>> 0.60% +0.17% +0.33% [kernel.vmlinux] [k] policy_nodemask >>> 0.58% -0.15% -0.12% [ebtables] [k] ebt_do_table >>> 0.52% -0.25% -0.22% [kernel.vmlinux] [k] __alloc_skb >>> ... >>> 0.42% +0.58% +0.59% [kernel.vmlinux] [k] eventfd_signal >>> ... >>> 0.32% +0.96% +0.93% [kernel.vmlinux] [k] finish_task_switch >>> ... >>> +1.50% +1.16% [kernel.vmlinux] [k] get_task_policy.part.9 >>> +0.40% +0.42% [kernel.vmlinux] [k] __skb_get_hash_symmetr >>> +0.39% +0.40% [kernel.vmlinux] [k] _copy_from_iter_full >>> +0.24% +0.23% [vhost_net] [k] vhost_net_buf_peek >>> >>> Server vhost: >>> >>> 61.93% -10.72% -10.91% [kernel.vmlinux] [k] raw_copy_to_user >>> 9.25% +0.47% +0.86% [kernel.vmlinux] [k] free_hot_cold_page >>> 5.16% +1.41% +1.57% [vhost] [k] vhost_get_vq_desc >>> 5.12% -3.81% -3.78% [kernel.vmlinux] [k] skb_release_data >>> 3.30% +0.42% +0.55% [kernel.vmlinux] [k] raw_copy_from_user >>> 1.29% +2.20% +2.28% [kernel.vmlinux] [k] copy_page_to_iter >>> 1.24% +1.65% +0.45% [vhost_net] [k] handle_rx >>> 1.08% +3.03% +2.85% [kernel.vmlinux] [k] __wake_up_sync_key >>> 0.96% +0.70% +1.10% [vhost] [k] translate_desc >>> 0.69% -0.20% -0.22% [kernel.vmlinux] [k] tun_do_read.part.10 >>> 0.69% [kernel.vmlinux] [k] tun_peek_len >>> 0.67% +0.75% +0.78% [kernel.vmlinux] [k] eventfd_signal >>> 0.52% +0.96% +0.98% [kernel.vmlinux] [k] finish_task_switch >>> 0.50% +0.05% +0.09% [vhost] [k] vhost_add_used_n >>> ... >>> +0.63% +0.58% [vhost_net] [k] vhost_net_buf_peek >>> +0.32% +0.32% [kernel.vmlinux] [k] _copy_to_iter >>> +0.19% +0.19% [kernel.vmlinux] [k] __skb_get_hash_symmetr >>> +0.11% +0.21% [vhost] [k] vhost_umem_interval_tr >>> >> >> Looks like for some unknown reason which leads more wakeups. >> >> Could you please try to attached patch to see if it solves or mitigate >> the issue? >> >> Thanks > > My bad, please try this. > > Thanks Thanks Jason. Built 4.13 + supplied patch, I see some decrease in wakeups, but there's still quite a bit more compared to 4.12 (baseline=4.12, delta1=4.13, delta2=4.13+patch): client: 2.00% +3.69% +2.55% [kernel.vmlinux] [k] __wake_up_sync_key server: 1.08% +3.03% +1.85% [kernel.vmlinux] [k] __wake_up_sync_key Throughput was roughly equivalent to base 4.13 (so, still seeing the regression w/ this patch applied).