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=-8.6 required=3.0 tests=DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 EA76AC072B5 for ; Fri, 24 May 2019 04:08:16 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B8BC42175B for ; Fri, 24 May 2019 04:08:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="uEOS4vpS" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B8BC42175B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id E4A39EF9; Fri, 24 May 2019 04:08:06 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id AD9F2DA1 for ; Fri, 24 May 2019 04:08:05 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-pf1-f193.google.com (mail-pf1-f193.google.com [209.85.210.193]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 50260F4 for ; Fri, 24 May 2019 04:08:05 +0000 (UTC) Received: by mail-pf1-f193.google.com with SMTP id v80so4489200pfa.3 for ; Thu, 23 May 2019 21:08:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=vxeV9ft42Z9weuRQsncwqOnoZhf6GFp447KDcblUrfk=; b=uEOS4vpSHdvXshyeyQ0iD5vi/t5HfXMC3vH5rAwA3MkTTMmV9SwBcKO6u2MgfwD9Qv rg1ur842IMCEA0od5Kz1Bv0neEZVP1EFQ2hnPy6aqnCPu5vv/305N8orS5j1TIBm7RZr DKlEvNF10U80id4FfPyCmZCEINE1FFalSGEjnvRo6BfpitC35mWn0iQrw5vn7AiTBhif Kxp6iu6brjDoyH44Gsj4iu6eW63mCBq11PMUMbdOAIsgMjTC3mx8K4KwGv1R93lWGzOB ZYth9SqRBCknZjn4lf5D7bcJSLyfsIhameDrjsQYZHjABq4YfuC8DW9+L0WJQsVTOnVj SZVw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=vxeV9ft42Z9weuRQsncwqOnoZhf6GFp447KDcblUrfk=; b=BRsywdzTK4nD2jj0iKofE2313RhogukpWinaA5pI0+87ZXG/0J83arxgEasTUkVO29 1y8aUL3evJraH99TvOn0orz1ch7per/ZavwmL9ci7yaexkt0rHqBfvxsHbNMb6j/Gf+N DHbNl/KTFMJWkOxEqzd/ktWznezBmaDTq0bjnjnJO5GhHNM5CX5yg5kZFmgTtaLAQnt4 0cQl5csqVCoDn0HQ/eyR6RmDAoTQBZo82Pw5uV1jv7sBOh4KqlzD5YiiUzZE3Kgs7gXT 1SOADNQvemez5umvkwj/sohe1Oxdx0wOKLaO8R38GUx0cAw8ttkguJWIS/M6zECVTuoP ZSOw== X-Gm-Message-State: APjAAAUwuKwrlC81ZPzQagvttchII2nntVQ31TE+6425jZyFZb+Bj/do /oZzlMqI2Gk8bvO1iSG+UHk= X-Google-Smtp-Source: APXvYqz3rANqBcGuU0hMuqFXJhoStKwnDv8T7RVd97CjQ1RaDUTPIv1XEAw8pA1ErKVwCpbE/Uq31g== X-Received: by 2002:a62:3605:: with SMTP id d5mr89150670pfa.28.1558670884755; Thu, 23 May 2019 21:08:04 -0700 (PDT) Received: from Asurada-Nvidia.nvidia.com (thunderhill.nvidia.com. [216.228.112.22]) by smtp.gmail.com with ESMTPSA id e123sm786412pgc.29.2019.05.23.21.08.03 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 23 May 2019 21:08:04 -0700 (PDT) From: Nicolin Chen To: hch@lst.de, robin.murphy@arm.com, m.szyprowski@samsung.com Subject: [PATCH v3 2/2] dma-contiguous: Use fallback alloc_pages for single pages Date: Thu, 23 May 2019 21:06:33 -0700 Message-Id: <20190524040633.16854-3-nicoleotsuka@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190524040633.16854-1-nicoleotsuka@gmail.com> References: <20190524040633.16854-1-nicoleotsuka@gmail.com> Cc: chris@zankel.net, linux-xtensa@linux-xtensa.org, keescook@chromium.org, sfr@canb.auug.org.au, tony@atomide.com, catalin.marinas@arm.com, will.deacon@arm.com, linux@armlinux.org.uk, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, jcmvbkbc@gmail.com, wsa+renesas@sang-engineering.com, dann.frazier@canonical.com, akpm@linux-foundation.org, treding@nvidia.com, dwmw2@infradead.org, iamjoonsoo.kim@lge.com, linux-arm-kernel@lists.infradead.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org The addresses within a single page are always contiguous, so it's not so necessary to always allocate one single page from CMA area. Since the CMA area has a limited predefined size of space, it may run out of space in heavy use cases, where there might be quite a lot CMA pages being allocated for single pages. However, there is also a concern that a device might care where a page comes from -- it might expect the page from CMA area and act differently if the page doesn't. This patch tries to use the fallback alloc_pages path, instead of one-page size allocations from the global CMA area in case that a device does not have its own CMA area. This'd save resources from the CMA global area for more CMA allocations, and also reduce CMA fragmentations resulted from trivial allocations. Signed-off-by: Nicolin Chen --- kernel/dma/contiguous.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c index 21f39a6cb04f..6914b92d5c88 100644 --- a/kernel/dma/contiguous.c +++ b/kernel/dma/contiguous.c @@ -223,14 +223,23 @@ bool dma_release_from_contiguous(struct device *dev, struct page *pages, * This function allocates contiguous memory buffer for specified device. It * first tries to use device specific contiguous memory area if available or * the default global one, then tries a fallback allocation of normal pages. + * + * Note that it byapss one-page size of allocations from the global area as + * the addresses within one page are always contiguous, so there is no need + * to waste CMA pages for that kind; it also helps reduce fragmentations. */ struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp) { int node = dev ? dev_to_node(dev) : NUMA_NO_NODE; size_t count = PAGE_ALIGN(size) >> PAGE_SHIFT; size_t align = get_order(PAGE_ALIGN(size)); - struct cma *cma = dev_get_cma_area(dev); struct page *page = NULL; + struct cma *cma = NULL; + + if (dev && dev->cma_area) + cma = dev->cma_area; + else if (count > 1) + cma = dma_contiguous_default_area; /* CMA can be used only in the context which permits sleeping */ if (cma && gfpflags_allow_blocking(gfp)) { -- 2.17.1 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu