From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 65024C433DB for ; Fri, 22 Jan 2021 03:10:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2935A23884 for ; Fri, 22 Jan 2021 03:10:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726015AbhAVDKS (ORCPT ); Thu, 21 Jan 2021 22:10:18 -0500 Received: from mga04.intel.com ([192.55.52.120]:26711 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725984AbhAVDKR (ORCPT ); Thu, 21 Jan 2021 22:10:17 -0500 IronPort-SDR: I9G1h0vuhc7k77WjRu1lu58gtnJwrZKtldKq44EvbsFj+jrZcj14DHaQfSLq+s18ZsQLHUeRPf FDtTFTLFxg6Q== X-IronPort-AV: E=McAfee;i="6000,8403,9871"; a="176809806" X-IronPort-AV: E=Sophos;i="5.79,365,1602572400"; d="scan'208";a="176809806" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Jan 2021 19:08:29 -0800 IronPort-SDR: 6CIrpZM9pDecYu2RuY0Xsy9icPJznw6ouOjEA9n1L+XeLhnAEYmCnlyJs7VtOJSbRruB17I5xj 6Z0BchqHlzqg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.79,365,1602572400"; d="scan'208";a="467701308" Received: from allen-box.sh.intel.com (HELO [10.239.159.28]) ([10.239.159.28]) by fmsmga001.fm.intel.com with ESMTP; 21 Jan 2021 19:08:26 -0800 Cc: baolu.lu@linux.intel.com, "iommu@lists.linux-foundation.org" , Will Deacon , linux-rdma , "logang@deltatee.com" , Christoph Hellwig , "murphyt7@tcd.ie" , isaacm@codeaurora.org Subject: Re: performance regression noted in v5.11-rc after c062db039f40 To: Chuck Lever , Robin Murphy References: <20210112143819.GA9689@willie-the-truck> <607648D8-BF0C-40D6-9B43-2359F45EE74C@oracle.com> <3568C74A-A587-4464-8840-24F7A93ABA06@oracle.com> From: Lu Baolu Message-ID: <990a7c1e-e8c0-a6a8-f057-03b104cebca3@linux.intel.com> Date: Fri, 22 Jan 2021 11:00:12 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <3568C74A-A587-4464-8840-24F7A93ABA06@oracle.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org +Isaac On 1/22/21 3:09 AM, Chuck Lever wrote: > > >> On Jan 18, 2021, at 1:00 PM, Robin Murphy wrote: >> >> On 2021-01-18 16:18, Chuck Lever wrote: >>>> On Jan 12, 2021, at 9:38 AM, Will Deacon wrote: >>>> >>>> [Expanding cc list to include DMA-IOMMU and intel IOMMU folks] >>>> >>>> On Fri, Jan 08, 2021 at 04:18:36PM -0500, Chuck Lever wrote: >>>>> Hi- >>>>> >>>>> [ Please cc: me on replies, I'm not currently subscribed to >>>>> iommu@lists ]. >>>>> >>>>> I'm running NFS performance tests on InfiniBand using CX-3 Pro cards >>>>> at 56Gb/s. The test is iozone on an NFSv3/RDMA mount: >>>>> >>>>> /home/cel/bin/iozone -M -+u -i0 -i1 -s1g -r256k -t12 -I >>>>> >>>>> For those not familiar with the way storage protocols use RDMA, The >>>>> initiator/client sets up memory regions and the target/server uses >>>>> RDMA Read and Write to move data out of and into those regions. The >>>>> initiator/client uses only RDMA memory registration and invalidation >>>>> operations, and the target/server uses RDMA Read and Write. >>>>> >>>>> My NFS client is a two-socket 12-core x86_64 system with its I/O MMU >>>>> enabled using the kernel command line options "intel_iommu=on >>>>> iommu=strict". >>>>> >>>>> Recently I've noticed a significant (25-30%) loss in NFS throughput. >>>>> I was able to bisect on my client to the following commits. >>>>> >>>>> Here's 65f746e8285f ("iommu: Add quirk for Intel graphic devices in >>>>> map_sg"). This is about normal for this test. >>>>> >>>>> Children see throughput for 12 initial writers = 4732581.09 kB/sec >>>>> Parent sees throughput for 12 initial writers = 4646810.21 kB/sec >>>>> Min throughput per process = 387764.34 kB/sec >>>>> Max throughput per process = 399655.47 kB/sec >>>>> Avg throughput per process = 394381.76 kB/sec >>>>> Min xfer = 1017344.00 kB >>>>> CPU Utilization: Wall time 2.671 CPU time 1.974 CPU utilization 73.89 % >>>>> Children see throughput for 12 rewriters = 4837741.94 kB/sec >>>>> Parent sees throughput for 12 rewriters = 4833509.35 kB/sec >>>>> Min throughput per process = 398983.72 kB/sec >>>>> Max throughput per process = 406199.66 kB/sec >>>>> Avg throughput per process = 403145.16 kB/sec >>>>> Min xfer = 1030656.00 kB >>>>> CPU utilization: Wall time 2.584 CPU time 1.959 CPU utilization 75.82 % >>>>> Children see throughput for 12 readers = 5921370.94 kB/sec >>>>> Parent sees throughput for 12 readers = 5914106.69 kB/sec >>>>> Min throughput per process = 491812.38 kB/sec >>>>> Max throughput per process = 494777.28 kB/sec >>>>> Avg throughput per process = 493447.58 kB/sec >>>>> Min xfer = 1042688.00 kB >>>>> CPU utilization: Wall time 2.122 CPU time 1.968 CPU utilization 92.75 % >>>>> Children see throughput for 12 re-readers = 5947985.69 kB/sec >>>>> Parent sees throughput for 12 re-readers = 5941348.51 kB/sec >>>>> Min throughput per process = 492805.81 kB/sec >>>>> Max throughput per process = 497280.19 kB/sec >>>>> Avg throughput per process = 495665.47 kB/sec >>>>> Min xfer = 1039360.00 kB >>>>> CPU utilization: Wall time 2.111 CPU time 1.968 CPU utilization 93.22 % >>>>> >>>>> Here's c062db039f40 ("iommu/vt-d: Update domain geometry in >>>>> iommu_ops.at(de)tach_dev"). It's losing some steam here. >>>>> >>>>> Children see throughput for 12 initial writers = 4342419.12 kB/sec >>>>> Parent sees throughput for 12 initial writers = 4310612.79 kB/sec >>>>> Min throughput per process = 359299.06 kB/sec >>>>> Max throughput per process = 363866.16 kB/sec >>>>> Avg throughput per process = 361868.26 kB/sec >>>>> Min xfer = 1035520.00 kB >>>>> CPU Utilization: Wall time 2.902 CPU time 1.951 CPU utilization 67.22 % >>>>> Children see throughput for 12 rewriters = 4408576.66 kB/sec >>>>> Parent sees throughput for 12 rewriters = 4404280.87 kB/sec >>>>> Min throughput per process = 364553.88 kB/sec >>>>> Max throughput per process = 370029.28 kB/sec >>>>> Avg throughput per process = 367381.39 kB/sec >>>>> Min xfer = 1033216.00 kB >>>>> CPU utilization: Wall time 2.836 CPU time 1.956 CPU utilization 68.97 % >>>>> Children see throughput for 12 readers = 5406879.47 kB/sec >>>>> Parent sees throughput for 12 readers = 5401862.78 kB/sec >>>>> Min throughput per process = 449583.03 kB/sec >>>>> Max throughput per process = 451761.69 kB/sec >>>>> Avg throughput per process = 450573.29 kB/sec >>>>> Min xfer = 1044224.00 kB >>>>> CPU utilization: Wall time 2.323 CPU time 1.977 CPU utilization 85.12 % >>>>> Children see throughput for 12 re-readers = 5410601.12 kB/sec >>>>> Parent sees throughput for 12 re-readers = 5403504.40 kB/sec >>>>> Min throughput per process = 449918.12 kB/sec >>>>> Max throughput per process = 452489.28 kB/sec >>>>> Avg throughput per process = 450883.43 kB/sec >>>>> Min xfer = 1043456.00 kB >>>>> CPU utilization: Wall time 2.321 CPU time 1.978 CPU utilization 85.21 % >>>>> >>>>> And here's c588072bba6b ("iommu/vt-d: Convert intel iommu driver to >>>>> the iommu ops"). Significant throughput loss. >>>>> >>>>> Children see throughput for 12 initial writers = 3812036.91 kB/sec >>>>> Parent sees throughput for 12 initial writers = 3753683.40 kB/sec >>>>> Min throughput per process = 313672.25 kB/sec >>>>> Max throughput per process = 321719.44 kB/sec >>>>> Avg throughput per process = 317669.74 kB/sec >>>>> Min xfer = 1022464.00 kB >>>>> CPU Utilization: Wall time 3.309 CPU time 1.986 CPU utilization 60.02 % >>>>> Children see throughput for 12 rewriters = 3786831.94 kB/sec >>>>> Parent sees throughput for 12 rewriters = 3783205.58 kB/sec >>>>> Min throughput per process = 313654.44 kB/sec >>>>> Max throughput per process = 317844.50 kB/sec >>>>> Avg throughput per process = 315569.33 kB/sec >>>>> Min xfer = 1035520.00 kB >>>>> CPU utilization: Wall time 3.302 CPU time 1.945 CPU utilization 58.90 % >>>>> Children see throughput for 12 readers = 4265828.28 kB/sec >>>>> Parent sees throughput for 12 readers = 4261844.88 kB/sec >>>>> Min throughput per process = 352305.00 kB/sec >>>>> Max throughput per process = 357726.22 kB/sec >>>>> Avg throughput per process = 355485.69 kB/sec >>>>> Min xfer = 1032960.00 kB >>>>> CPU utilization: Wall time 2.934 CPU time 1.942 CPU utilization 66.20 % >>>>> Children see throughput for 12 re-readers = 4220651.19 kB/sec >>>>> Parent sees throughput for 12 re-readers = 4216096.04 kB/sec >>>>> Min throughput per process = 348677.16 kB/sec >>>>> Max throughput per process = 353467.44 kB/sec >>>>> Avg throughput per process = 351720.93 kB/sec >>>>> Min xfer = 1035264.00 kB >>>>> CPU utilization: Wall time 2.969 CPU time 1.952 CPU utilization 65.74 % >>>>> >>>>> The regression appears to be 100% reproducible. >>> Any thoughts? >>> How about some tools to try or debugging advice? I don't know where to start. >> >> I'm not familiar enough with VT-D internals or Infiniband to have a clue why the middle commit makes any difference (the calculation itself is not on a fast path, so AFAICS the worst it could do is change your maximum DMA address size from 48/57 bits to 47/56, and that seems relatively benign). >> >> With the last commit, though, at least part of it is likely to be the unfortunate inevitable overhead of the internal indirection through the IOMMU API. There's a coincidental performance-related thread where we've already started pondering some ideas in that area[1] (note that Intel is the last one to the party here; AMD has been using this path for a while, and it's all that arm64 systems have ever known). I'm not sure if there's any difference in the strict invalidation behaviour between the IOMMU API calls and the old intel_dma_ops, but I suppose that might be worth quickly double-checking as well. I guess the main thing would be to do some profiling to see where time is being spent in iommu-dma and intel-iommu vs. just different parts of intel-iommu before, and whether anything in particular stands out beyond the extra call overhead currently incurred by iommu_{map,unmap}. > > I did a function_graph trace of the above iozone test on a v5.10 NFS > client and again on v5.11-rc. There is a substantial timing difference > in dma_map_sg_attrs. Each excerpt below is for DMA-mapping a 120KB set > of pages that are part of an NFS/RDMA WRITE operation. > > v5.10: > > 1072.028308: funcgraph_entry: | dma_map_sg_attrs() { > 1072.028308: funcgraph_entry: | intel_map_sg() { > 1072.028309: funcgraph_entry: | find_domain() { > 1072.028309: funcgraph_entry: 0.280 us | get_domain_info(); > 1072.028310: funcgraph_exit: 0.930 us | } > 1072.028310: funcgraph_entry: 0.360 us | domain_get_iommu(); > 1072.028311: funcgraph_entry: | intel_alloc_iova() { > 1072.028311: funcgraph_entry: | alloc_iova_fast() { > 1072.028311: funcgraph_entry: 0.375 us | _raw_spin_lock_irqsave(); > 1072.028312: funcgraph_entry: 0.285 us | __lock_text_start(); > 1072.028313: funcgraph_exit: 1.500 us | } > 1072.028313: funcgraph_exit: 2.052 us | } > 1072.028313: funcgraph_entry: | domain_mapping() { > 1072.028313: funcgraph_entry: | __domain_mapping() { > 1072.028314: funcgraph_entry: 0.350 us | pfn_to_dma_pte(); > 1072.028315: funcgraph_entry: 0.942 us | domain_flush_cache(); > 1072.028316: funcgraph_exit: 2.852 us | } > 1072.028316: funcgraph_entry: 0.275 us | iommu_flush_write_buffer(); > 1072.028317: funcgraph_exit: 4.213 us | } > 1072.028318: funcgraph_exit: 9.392 us | } > 1072.028318: funcgraph_exit: + 10.073 us | } > 1072.028323: xprtrdma_mr_map: mr.id=115 nents=30 122880@0xe476ca03f1180000:0x18011105 (TO_DEVICE) > 1072.028323: xprtrdma_chunk_read: task:63879@5 pos=148 122880@0xe476ca03f1180000:0x18011105 (more) > > > v5.11-rc: > > 57.602990: funcgraph_entry: | dma_map_sg_attrs() { > 57.602990: funcgraph_entry: | iommu_dma_map_sg() { > 57.602990: funcgraph_entry: 0.285 us | iommu_get_dma_domain(); > 57.602991: funcgraph_entry: 0.270 us | iommu_dma_deferred_attach(); > 57.602991: funcgraph_entry: | iommu_dma_sync_sg_for_device() { > 57.602992: funcgraph_entry: 0.268 us | dev_is_untrusted(); > 57.602992: funcgraph_exit: 0.815 us | } > 57.602993: funcgraph_entry: 0.267 us | dev_is_untrusted(); > 57.602993: funcgraph_entry: | iommu_dma_alloc_iova() { > 57.602994: funcgraph_entry: | alloc_iova_fast() { > 57.602994: funcgraph_entry: 0.260 us | _raw_spin_lock_irqsave(); > 57.602995: funcgraph_entry: 0.293 us | _raw_spin_lock(); > 57.602995: funcgraph_entry: 0.273 us | _raw_spin_unlock_irqrestore(); > 57.602996: funcgraph_entry: 1.147 us | alloc_iova(); > 57.602997: funcgraph_exit: 3.370 us | } > 57.602997: funcgraph_exit: 3.945 us | } > 57.602998: funcgraph_entry: 0.272 us | dma_info_to_prot(); > 57.602998: funcgraph_entry: | iommu_map_sg_atomic() { > 57.602998: funcgraph_entry: | __iommu_map_sg() { > 57.602999: funcgraph_entry: 1.733 us | __iommu_map(); > 57.603001: funcgraph_entry: 1.642 us | __iommu_map(); > 57.603003: funcgraph_entry: 1.638 us | __iommu_map(); > 57.603005: funcgraph_entry: 1.645 us | __iommu_map(); > 57.603007: funcgraph_entry: 1.630 us | __iommu_map(); > 57.603009: funcgraph_entry: 1.770 us | __iommu_map(); > 57.603011: funcgraph_entry: 1.730 us | __iommu_map(); > 57.603013: funcgraph_entry: 1.633 us | __iommu_map(); > 57.603015: funcgraph_entry: 1.605 us | __iommu_map(); > 57.603017: funcgraph_entry: 2.847 us | __iommu_map(); > 57.603020: funcgraph_entry: 2.847 us | __iommu_map(); > 57.603024: funcgraph_entry: 2.955 us | __iommu_map(); > 57.603027: funcgraph_entry: 2.928 us | __iommu_map(); > 57.603030: funcgraph_entry: 2.933 us | __iommu_map(); > 57.603034: funcgraph_entry: 2.943 us | __iommu_map(); > 57.603037: funcgraph_entry: 2.928 us | __iommu_map(); > 57.603040: funcgraph_entry: 2.857 us | __iommu_map(); > 57.603044: funcgraph_entry: 2.953 us | __iommu_map(); > 57.603047: funcgraph_entry: 3.023 us | __iommu_map(); > 57.603050: funcgraph_entry: 1.645 us | __iommu_map(); > 57.603052: funcgraph_exit: + 53.648 us | } > 57.603052: funcgraph_exit: + 54.178 us | } > 57.603053: funcgraph_exit: + 62.953 us | } > 57.603053: funcgraph_exit: + 63.567 us | } > 57.603059: xprtrdma_mr_map: task:60@5 mr.id=4 nents=30 122880@0xd79cc0e2f18c0000:0x00010501 (TO_DEVICE) > 57.603060: xprtrdma_chunk_read: task:60@5 pos=148 122880@0xd79cc0e2f18c0000:0x00010501 (more) > I kind of believe it's due to the indirect calls. This is also reported on ARM. https://lore.kernel.org/linux-iommu/1610376862-927-1-git-send-email-isaacm@codeaurora.org/ Maybe we can try changing indirect calls to static ones to verify this problem. Best regards, baolu