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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E1FC7EB3624 for ; Mon, 2 Mar 2026 19:53:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To: Content-Type:MIME-Version:References:Message-ID:Subject:To:From:Date:Reply-To :Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=8MDNbjTixOfa0GTM9nILFTTji9y/2YCrVQk64vFZ2cs=; b=ilVvt0DLUZwLYgR9i2Mz6Rkx9Z RmXHehsuAIr77ZHEN0KDng5i+sRAQkoKp6yxnYLnsnHiXL7UXuqS8NCj/UeAEFLxe5uPE/swk5xtq UDh9gqRxKgCWhhIw2OiOQLByWDUzp19GZ+Jx9pTXijAU9dYx5RGdfwq/eqe7V6PpS8KRd1yudddyW NZINlngL19UYOLqh1cZQh8UOmKjj57rM+psm3JepefxD7ATETlslZUytZ1ziE1nOMlUiOnrXJsYHS uDpydtifFoOcSgX8O2yBHwZ/n+skEOV0lO6WT6rPvoyCP317tGsZ+pCED2hNZ7rW22MbKAxULhT3f LbqO8Qpg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vx9Kl-0000000DlMZ-3yXN; Mon, 02 Mar 2026 19:53:39 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vx9Kj-0000000DlMD-2Huy for linux-arm-kernel@lists.infradead.org; Mon, 02 Mar 2026 19:53:38 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 2F40440558; Mon, 2 Mar 2026 19:53:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 633BEC19423; Mon, 2 Mar 2026 19:53:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772481216; bh=iHd9xTb08uobwrAOBK6bO4QNR4IAuCt806zIdYOX5us=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=S/dJT0zySAqwi8FaZNed1bZHgZoUCgkvtEoN8t/qyxZFp4cdB5l4QCVShqLeQMGVe rRPW0Y3cs4dBSlhGNTkgQg/LYvrMJYcaWCCWfoOUveyHYK9JvZQGSYvyb702arb/ea mbb3qgrBoqHQHfWLA8bq5WvBMzRmeNSQ8woJOAhXYpaXIvvhpUM1npi9Clw4oTIdA0 YcoCj5pjyU5NRwaWwqatyon0UBxknUprtI9HCyltId6WEljYAa6ne6Sr5pLHyPMo3q khGXgG+xXggQ6qmt1ilyq3HDMADuB/j+MgYxCkEX2+8kWdr8QjQM9CzSEetoFBMZa2 LUQYeASDCnoZg== Date: Mon, 2 Mar 2026 21:53:32 +0200 From: Leon Romanovsky To: Barry Song <21cnbao@gmail.com> Subject: Re: [PATCH v3 4/5] dma-mapping: Separate DMA sync issuing and completion waiting Message-ID: <20260302195332.GV12611@unreal> References: <20260228221316.59934-1-21cnbao@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260228221316.59934-1-21cnbao@gmail.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260302_115337_625320_3A2FE4A1 X-CRM114-Status: GOOD ( 15.25 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juergen Gross , Tangquan Zheng , Barry Song , Stefano Stabellini , Ryan Roberts , will@kernel.org, Anshuman Khandual , catalin.marinas@arm.com, Joerg Roedel , linux-kernel@vger.kernel.org, Suren Baghdasaryan , iommu@lists.linux.dev, Xueyuan Chen , Marc Zyngier , Oleksandr Tyshchenko , robin.murphy@arm.com, Ard Biesheuvel , linux-arm-kernel@lists.infradead.org, m.szyprowski@samsung.com Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sun, Mar 01, 2026 at 06:13:16AM +0800, Barry Song wrote: > From: Barry Song > > Currently, arch_sync_dma_for_cpu and arch_sync_dma_for_device > always wait for the completion of each DMA buffer. That is, > issuing the DMA sync and waiting for completion is done in a > single API call. > > For scatter-gather lists with multiple entries, this means > issuing and waiting is repeated for each entry, which can hurt > performance. Architectures like ARM64 may be able to issue all > DMA sync operations for all entries first and then wait for > completion together. > > To address this, arch_sync_dma_for_* now batches DMA operations > and performs a flush afterward. On ARM64, the flush is implemented > with a dsb instruction in arch_sync_dma_flush(). On other > architectures, arch_sync_dma_flush() is currently a nop. > > Cc: Leon Romanovsky > Cc: Catalin Marinas > Cc: Will Deacon > Cc: Marek Szyprowski > Cc: Robin Murphy > Cc: Ada Couprie Diaz > Cc: Ard Biesheuvel > Cc: Marc Zyngier > Cc: Anshuman Khandual > Cc: Ryan Roberts > Cc: Suren Baghdasaryan > Cc: Joerg Roedel > Cc: Stefano Stabellini > Cc: Oleksandr Tyshchenko > Cc: Tangquan Zheng > Reviewed-by: Juergen Gross # drivers/xen/swiotlb-xen.c > Tested-by: Xueyuan Chen > Signed-off-by: Barry Song > --- > arch/arm64/Kconfig | 1 + > arch/arm64/include/asm/cache.h | 5 +++++ > arch/arm64/mm/dma-mapping.c | 4 ++-- > drivers/iommu/dma-iommu.c | 35 ++++++++++++++++++++++++++-------- > drivers/xen/swiotlb-xen.c | 24 +++++++++++++++-------- > include/linux/dma-map-ops.h | 6 ++++++ > kernel/dma/Kconfig | 3 +++ > kernel/dma/direct.c | 6 +++++- > kernel/dma/direct.h | 9 +++++++-- > kernel/dma/swiotlb.c | 7 ++++++- > 10 files changed, 78 insertions(+), 22 deletions(-) > Thanks, Reviewed-by: Leon Romanovsky