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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 78EABECAAD2 for ; Fri, 26 Aug 2022 08:58:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245567AbiHZI6z (ORCPT ); Fri, 26 Aug 2022 04:58:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40612 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245273AbiHZI6x (ORCPT ); Fri, 26 Aug 2022 04:58:53 -0400 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C027CD5EA0 for ; Fri, 26 Aug 2022 01:58:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1661504332; x=1693040332; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=qd4FqNTu52qrVx/MtAe2JAV2sDMVlYfag3oD7tG2ki4=; b=muOjGmFQcmTFEBYe9bMnEUW5AxmUVC9tAPaWd2FV22FMupXa88RoYtr6 bcj9LEbqkMBvsZdILrmE9OKj517xddltLmfpJcMt689LoFwYT7QC4DlXW 3GfsgOl73IlrqIjmlas55vnvn1HBwS9n5PeIrzONEAGzp2axFiFoJYIdI dxp/W54v+L0xL03MrWnO4aewUJhBaMHJAiD4YokXl2l0gM0kkIrhPMbV/ O/k/eoajjF5RFDKfHgZ0CwxHKEDBMlYTzt6zkdFWu1r4njf7h5nCcQvVj J0ZRtx/+5PJ6xmo5JL4O3VmtP7v0CRh/67ZHwzapgtHO1WU6kiO6b5RVy g==; X-IronPort-AV: E=McAfee;i="6500,9779,10450"; a="293203228" X-IronPort-AV: E=Sophos;i="5.93,264,1654585200"; d="scan'208";a="293203228" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Aug 2022 01:58:52 -0700 X-IronPort-AV: E=Sophos;i="5.93,264,1654585200"; d="scan'208";a="671383823" Received: from zhaohaif-mobl1.ccr.corp.intel.com (HELO [10.254.212.242]) ([10.254.212.242]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Aug 2022 01:58:50 -0700 Message-ID: Date: Fri, 26 Aug 2022 16:58:48 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.13.0 Subject: Re: [External] Re: [PATCH v2] iommu/iova: Optimize alloc_iova with rbtree_augmented To: Peng Zhang , joro@8bytes.org, will@kernel.org Cc: iommu@lists.linux.dev, linux-kernel@vger.kernel.org, robin.murphy@arm.com References: <20220824095139.66477-1-zhangpeng.00@bytedance.com> <06c215c6-cbae-d6b9-312c-6535e51a3128@linux.intel.com> <486fcde8-e9f5-e40c-db5d-fd3ade59b267@bytedance.com> From: Ethan Zhao In-Reply-To: <486fcde8-e9f5-e40c-db5d-fd3ade59b267@bytedance.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Peng, 在 2022/8/25 16:10, Peng Zhang 写道: > > Hi, > > Here is a real example. The version of kernel is 5.4.56. > Occurs when a lot of iova are not released for a long time. > > [Wed May 25 05:27:59 2022] watchdog: BUG: soft lockup - CPU#58 stuck > for 23s! [ksoftirqd/58:302] > [Wed May 25 05:27:59 2022] Call Trace: > [Wed May 25 05:27:59 2022]  alloc_iova+0xf2/0x140 > [Wed May 25 05:27:59 2022]  alloc_iova_fast+0x56/0x251 The rcache doesn't work at all , the worst case. > [Wed May 25 05:27:59 2022]  dma_ops_alloc_iova.isra.27+0x4b/0x70 > [Wed May 25 05:27:59 2022]  __map_single.isra.28+0x4a/0x1d0 > [Wed May 25 05:27:59 2022]  mlx5e_sq_xmit+0x98d/0x12b0 [mlx5_core] > [Wed May 25 05:27:59 2022]  ? packet_rcv+0x43/0x460 > [Wed May 25 05:27:59 2022]  ? dev_hard_start_xmit+0x90/0x1e0 > [Wed May 25 05:27:59 2022]  ? sch_direct_xmit+0x111/0x320 > [Wed May 25 05:27:59 2022]  ? __qdisc_run+0x143/0x540 > [Wed May 25 05:27:59 2022]  ? __dev_queue_xmit+0x6c3/0x8e0 > [Wed May 25 05:27:59 2022]  ? ip_finish_output2+0x2d5/0x580 > [Wed May 25 05:27:59 2022]  ? __ip_finish_output+0xe9/0x1b0 > [Wed May 25 05:27:59 2022]  ? ip_output+0x6c/0xe0 > [Wed May 25 05:27:59 2022]  ? __ip_finish_output+0x1b0/0x1b0 > [Wed May 25 05:27:59 2022]  ? __ip_queue_xmit+0x15d/0x420 > [Wed May 25 05:27:59 2022]  ? __tcp_transmit_skb+0x405/0x600 > [Wed May 25 05:27:59 2022]  ? tcp_delack_timer_handler+0xb7/0x1b0 > [Wed May 25 05:27:59 2022]  ? tcp_delack_timer+0x8b/0xa0 > [Wed May 25 05:27:59 2022]  ? tcp_delack_timer_handler+0x1b0/0x1b0 > [Wed May 25 05:27:59 2022]  ? call_timer_fn+0x2b/0x120 > [Wed May 25 05:27:59 2022]  ? run_timer_softirq+0x1a6/0x420 > [Wed May 25 05:27:59 2022]  ? update_load_avg+0x7e/0x640 > [Wed May 25 05:27:59 2022]  ? update_curr+0xe1/0x1d0 > [Wed May 25 05:27:59 2022]  ? __switch_to+0x7a/0x3e0 > [Wed May 25 05:27:59 2022]  ? __do_softirq+0xda/0x2da > [Wed May 25 05:27:59 2022]  ? sort_range+0x20/0x20 > [Wed May 25 05:27:59 2022]  ? run_ksoftirqd+0x26/0x40 > [Wed May 25 05:27:59 2022]  ? smpboot_thread_fn+0xb8/0x150 > [Wed May 25 05:27:59 2022]  ? kthread+0x110/0x130 > [Wed May 25 05:27:59 2022]  ? kthread_park+0x80/0x80 > [Wed May 25 05:27:59 2022]  ? ret_from_fork+0x1f/0x30 > > I did some more tests. > > The test is single threaded. > Granule is 4k, limit is 2^20. > > When the 1/4 address space is occupied by iova, > Repeat the following two steps： > > 1. Randomly releases an iova. > 2. Allocate an iova of size 1 within the allocation limit of 2^20. > > Before improvement: >> Tracing 1 functions for "alloc_iova"... Hit Ctrl-C to end. >> ^C >>      nsecs               : count     distribution >>          0 -> 1          : 0 |                                        | >>          2 -> 3          : 0 |                                        | >>          4 -> 7          : 0 |                                        | >>          8 -> 15         : 0 |                                        | >>         16 -> 31         : 0 |                                        | >>         32 -> 63         : 0 |                                        | >>         64 -> 127        : 0 |                                        | >>        128 -> 255        : 0 |                                        | >>        256 -> 511        : 352 >> |                                        | >>        512 -> 1023       : 258078 >> |****************************************| >>       1024 -> 2047       : 3612 >> |                                        | >>       2048 -> 4095       : 426 >> |                                        | >>       4096 -> 8191       : 183 >> |                                        | >>       8192 -> 16383      : 6 |                                        | >>      16384 -> 32767      : 5 |                                        | >>      32768 -> 65535      : 9 |                                        | >>      65536 -> 131071     : 18 |                                        | >>     131072 -> 262143     : 28 |                                        | >>     262144 -> 524287     : 74 |                                        | >>     524288 -> 1048575    : 109 >> |                                        | >>    1048576 -> 2097151    : 170 >> |                                        | >>    2097152 -> 4194303    : 100 >> |                                        | >>    4194304 -> 8388607    : 1 |                                        | >> >> avg = 3110 nsecs, total: 818614399 nsecs, count: 263171 >> >> Tracing 1 functions for "remove_iova"... Hit Ctrl-C to end. >> ^C >>      nsecs               : count     distribution >>          0 -> 1          : 0 |                                        | >>          2 -> 3          : 0 |                                        | >>          4 -> 7          : 0 |                                        | >>          8 -> 15         : 0 |                                        | >>         16 -> 31         : 0 |                                        | >>         32 -> 63         : 0 |                                        | >>         64 -> 127        : 0 |                                        | >>        128 -> 255        : 0 |                                        | >>        256 -> 511        : 250651 >> |****************************************| >>        512 -> 1023       : 12405 >> |*                                       | >>       1024 -> 2047       : 111 >> |                                        | >>       2048 -> 4095       : 1 |                                        | >> >> avg = 433 nsecs, total: 114136319 nsecs, count: 263168 > > With improvement: >> Tracing 1 functions for "alloc_iova"... Hit Ctrl-C to end. >> ^C >>      nsecs               : count     distribution >>          0 -> 1          : 0 |                                        | >>          2 -> 3          : 0 |                                        | >>          4 -> 7          : 0 |                                        | >>          8 -> 15         : 0 |                                        | >>         16 -> 31         : 0 |                                        | >>         32 -> 63         : 0 |                                        | >>         64 -> 127        : 0 |                                        | >>        128 -> 255        : 0 |                                        | >>        256 -> 511        : 0 |                                        | >>        512 -> 1023       : 258975 >> |****************************************| >>       1024 -> 2047       : 3618 >> |                                        | >>       2048 -> 4095       : 497 >> |                                        | >>       4096 -> 8191       : 74 |                                        | >>       8192 -> 16383      : 4 |                                        | >>      16384 -> 32767      : 1 |                                        | >> >> avg = 637 nsecs, total: 167854061 nsecs, count: 263169 >> >> Tracing 1 functions for "remove_iova"... Hit Ctrl-C to end. >> ^C >>      nsecs               : count     distribution >>          0 -> 1          : 0 |                                        | >>          2 -> 3          : 0 |                                        | >>          4 -> 7          : 0 |                                        | >>          8 -> 15         : 0 |                                        | >>         16 -> 31         : 0 |                                        | >>         32 -> 63         : 0 |                                        | >>         64 -> 127        : 0 |                                        | >>        128 -> 255        : 0 |                                        | >>        256 -> 511        : 221560 >> |****************************************| >>        512 -> 1023       : 41427 >> |*******                                 | >>       1024 -> 2047       : 179 >> |                                        | >>       2048 -> 4095       : 2 |                                        | >> >> avg = 477 nsecs, total: 125540399 nsecs, count: 263168 Though only 3-4 drivers use alloc_iova() directly, in my understanding your test has simulated the worst case, rcache doesn't work at all, "alloc_iova" +“remove_iova” number looks great for worst case. Reviewed-by: Ethan Zhao > >> s/distbution/distribution ? > Sorry, it's a typo. > > I don't have a test program for "alloc_iova_fast + free_iova_fast" > right now. > > Thanks, > > Peng -- "firm, enduring, strong, and long-lived"