From patchwork Fri Jun 18 02:51:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sai Prakash Ranjan X-Patchwork-Id: 463167 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=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 1B415C48BE5 for ; Fri, 18 Jun 2021 02:51:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EF51461241 for ; Fri, 18 Jun 2021 02:51:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230515AbhFRCyA (ORCPT ); Thu, 17 Jun 2021 22:54:00 -0400 Received: from so254-9.mailgun.net ([198.61.254.9]:24291 "EHLO so254-9.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230334AbhFRCx7 (ORCPT ); Thu, 17 Jun 2021 22:53:59 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1623984711; h=Content-Transfer-Encoding: MIME-Version: References: In-Reply-To: Message-Id: Date: Subject: Cc: To: From: Sender; bh=xxSjvx9FX3p13QwnOpawsCd6aq6mAIMLGM9MTx8atwg=; b=g6JoWOq85/m3VzewmiUeGGdyNk6XSK7soaX2kIbAyjB5w0VvMovX4m9J4pUpYwIZYIXO9j5N S0DRb2ThPlZXWFqMcIzWwGAg8yTkYy2rxM4G4FNBpy/tTTd0Pd5wkg3qzEFkdRz91Asc9ivN wqbiPhJzzuVRQsVSsCNxHi8fFfI= X-Mailgun-Sending-Ip: 198.61.254.9 X-Mailgun-Sid: WyI1MzIzYiIsICJsaW51eC1hcm0tbXNtQHZnZXIua2VybmVsLm9yZyIsICJiZTllNGEiXQ== Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n03.prod.us-west-2.postgun.com with SMTP id 60cc0a34ed59bf69ccb35a2b (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Fri, 18 Jun 2021 02:51:32 GMT Sender: saiprakash.ranjan=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 918C9C43217; Fri, 18 Jun 2021 02:51:32 +0000 (UTC) Received: from blr-ubuntu-253.qualcomm.com (blr-bdr-fw-01_GlobalNAT_AllZones-Outside.qualcomm.com [103.229.18.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: saiprakash.ranjan) by smtp.codeaurora.org (Postfix) with ESMTPSA id 2260DC43460; Fri, 18 Jun 2021 02:51:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 2260DC43460 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=saiprakash.ranjan@codeaurora.org From: Sai Prakash Ranjan To: Will Deacon , Robin Murphy , Joerg Roedel Cc: iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, Bjorn Andersson , Douglas Anderson , Krishna Reddy , Thierry Reding , Tomasz Figa , Sai Prakash Ranjan Subject: [PATCHv2 2/3] iommu/io-pgtable: Optimize partial walk flush for large scatter-gather list Date: Fri, 18 Jun 2021 08:21:04 +0530 Message-Id: <150fc7ab1c7f9b70a95dae1f4bc3b9018c0f9e04.1623981933.git.saiprakash.ranjan@codeaurora.org> X-Mailer: git-send-email 2.29.0 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org Currently for iommu_unmap() of large scatter-gather list with page size elements, the majority of time is spent in flushing of partial walks in __arm_lpae_unmap() which is a VA based TLB invalidation invalidating page-by-page on iommus like arm-smmu-v2 (TLBIVA) which do not support range based invalidations like on arm-smmu-v3.2. For example: to unmap a 32MB scatter-gather list with page size elements (8192 entries), there are 16->2MB buffer unmaps based on the pgsize (2MB for 4K granule) and each of 2MB will further result in 512 TLBIVAs (2MB/4K) resulting in a total of 8192 TLBIVAs (512*16) for 16->2MB causing a huge overhead. So instead use tlb_flush_all() callback (TLBIALL/TLBIASID) to invalidate the entire context for partial walk flush on select few platforms where cost of over-invalidation is less than unmap latency using the newly introduced quirk IO_PGTABLE_QUIRK_TLB_INV_ALL. We also do this for non-strict mode given its all about over-invalidation saving time on individual unmaps and non-deterministic generally. For this example of 32MB scatter-gather list unmap, this results in just 16 ASID based TLB invalidations (TLBIASIDs) as opposed to 8192 TLBIVAs thereby increasing the performance of unmaps drastically. Test on QTI SM8150 SoC for 10 iterations of iommu_{map_sg}/unmap: (average over 10 iterations) Before this optimization: size iommu_map_sg iommu_unmap 4K 2.067 us 1.854 us 64K 9.598 us 8.802 us 1M 148.890 us 130.718 us 2M 305.864 us 67.291 us 12M 1793.604 us 390.838 us 16M 2386.848 us 518.187 us 24M 3563.296 us 775.989 us 32M 4747.171 us 1033.364 us After this optimization: size iommu_map_sg iommu_unmap 4K 1.723 us 1.765 us 64K 9.880 us 8.869 us 1M 155.364 us 135.223 us 2M 303.906 us 5.385 us 12M 1786.557 us 21.250 us 16M 2391.890 us 27.437 us 24M 3570.895 us 39.937 us 32M 4755.234 us 51.797 us This is further reduced once the map/unmap_pages() support gets in which will result in just 1 TLBIASID as compared to 16 TLBIASIDs. Real world data also shows big difference in unmap performance as below: There were reports of camera frame drops because of high overhead in iommu unmap without this optimization because of frequent unmaps issued by camera of about 100MB/s taking more than 100ms thereby causing frame drops. Signed-off-by: Sai Prakash Ranjan --- include/linux/io-pgtable.h | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h index 45441592a0e6..fd6b30cfdbf7 100644 --- a/include/linux/io-pgtable.h +++ b/include/linux/io-pgtable.h @@ -219,6 +219,12 @@ static inline void io_pgtable_tlb_flush_walk(struct io_pgtable *iop, unsigned long iova, size_t size, size_t granule) { + if (iop->cfg.quirks & IO_PGTABLE_QUIRK_NON_STRICT || + iop->cfg.quirks & IO_PGTABLE_QUIRK_TLB_INV_ALL) { + iop->cfg.tlb->tlb_flush_all(iop->cookie); + return; + } + if (iop->cfg.tlb && iop->cfg.tlb->tlb_flush_walk) iop->cfg.tlb->tlb_flush_walk(iova, size, granule, iop->cookie); }