From patchwork Tue Apr 30 01:55:21 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nicolin Chen X-Patchwork-Id: 10922721 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id ABC7015A6 for ; Tue, 30 Apr 2019 01:57:33 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 98E00289BA for ; Tue, 30 Apr 2019 01:57:33 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8C3A1289BF; Tue, 30 Apr 2019 01:57:33 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED,DKIM_VALID,FREEMAIL_FROM,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 33D38289BA for ; Tue, 30 Apr 2019 01:57:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=pK9g/tKPkagaC676qNfu08cL180JRKp74+mkp11LkBA=; b=Qvja3Z1r4vxM16Px5GhAzdzJPG x/hMm+GB8Ddc4IG/EPXSs0KZb2tfd7iNHwZnrnx5g4gunfr5C2MU8KfK9DM6kVqweDjFxOrFNAn9W xUHNp/rtetLUk3N+avuWtuFx7d2pbW+rGxZRE/Y7geA+876GoanZuDH7o1eYXQoIc9PoU1P76NStG 33cXa6/sr28QW3Bx3Hjzy0rJU2x8H97UIUeQnC3AV2Grjw5sen1iKrunhKn6n6akNlW5yxEafnLpA 5j5tSkHYws4564w54WBJoUKeIJZjf7frlToQMr6W98BBzlYtCp8JV+H9Gkxaxk6yuyU5rZM8xmMgz KcGmYV3w==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hLI1Q-0006ii-1U; Tue, 30 Apr 2019 01:57:28 +0000 Received: from mail-pf1-x441.google.com ([2607:f8b0:4864:20::441]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1hLI12-0006IT-Jr for linux-arm-kernel@lists.infradead.org; Tue, 30 Apr 2019 01:57:05 +0000 Received: by mail-pf1-x441.google.com with SMTP id v80so1667070pfa.3 for ; Mon, 29 Apr 2019 18:57:04 -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=s8UYDA0A35ZvIDjqUXHlnj64LOZDrFMTPlT84kyIZ/A=; b=M87On/OVQyBg+MT1fVPE7dKNwirCzXjLqib8e9Rziw1Ivr/4fR4X+fNYh7Z6Q7F582 9l6GJBGPMqJqDugoryFUtON6Rziuv8o26pwNLS1Gkeqe4XaanoSK/EuQcmYltcUFjj1j rApDbk9/KkrxFqAqefRKrCatfUmoW/xFrSBF5Zl6ZaCffNYX4fuHXBSllNEcbp1fyXSy XY//ob5MYUHZZ6zVoCf+wezYjw9eeQNrLgq0Y+YMCYYbPnrh9scxIyGMB0cp+3R1f6nV r+mw+cUCZj0+/w5ylx8X+5oXwyKyvtA87jgmz5NmzWWzw7bGJL94m5dvcxkkFAjNucsm gHuA== 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=s8UYDA0A35ZvIDjqUXHlnj64LOZDrFMTPlT84kyIZ/A=; b=n/VpYF6p+WHaekPmUfOxK7ALrlhCvtYKGAzv0yS/btN6+14M7N7em9EibLtt8tL6Tm RYDx8ANXkPgKZtiajhfhbGaOKZiciFvg+5TCRDA/55+QWZz5ZDCVlFuHc1sitCC34tkE 1yLhfzWPidREkl4JASzovPOWSl2rZsktY7l4kgD5E/iEFF2wEUIPuoBDsrRO5ITm9j2o Nm/qgEmo40xb6lcLuogl3G7WBvITrPlqARw2SJwTbswNdq4NJ/9ZtwS3FDa1iyHjb0ij C/1nqakGkKukH7d+fTRcv7l29FAacaxTT0Pesvurj3ew6RsFN66lRkgVYXJk8GFs7TYh 1yyw== X-Gm-Message-State: APjAAAWD5asSlh56pZBTJCFP5EV93yJm7ndM5cJodacxSdTYS/ufsq4D 4E2S0cayattLlDn5+sDqo5w= X-Google-Smtp-Source: APXvYqzD4hPvjqmWE2q801NZMH8qACSDt5uAhDTlNqVfP4C95RfP3OVEnzocGAEnXIXXblyEUKqGYg== X-Received: by 2002:a63:8741:: with SMTP id i62mr12431618pge.313.1556589423757; Mon, 29 Apr 2019 18:57:03 -0700 (PDT) Received: from Asurada-Nvidia.nvidia.com (thunderhill.nvidia.com. [216.228.112.22]) by smtp.gmail.com with ESMTPSA id a12sm36918995pgq.21.2019.04.29.18.57.02 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 29 Apr 2019 18:57:03 -0700 (PDT) From: Nicolin Chen To: hch@lst.de, robin.murphy@arm.com, m.szyprowski@samsung.com Subject: [RFC/RFT PATCH 2/2] dma-contiguous: Use fallback alloc_pages for single pages Date: Mon, 29 Apr 2019 18:55:21 -0700 Message-Id: <20190430015521.27734-3-nicoleotsuka@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190430015521.27734-1-nicoleotsuka@gmail.com> References: <20190430015521.27734-1-nicoleotsuka@gmail.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190429_185704_648868_AF2B0EB6 X-CRM114-Status: GOOD ( 16.60 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: chris@zankel.net, linux-xtensa@linux-xtensa.org, keescook@chromium.org, sfr@canb.auug.org.au, tony@atomide.com, catalin.marinas@arm.com, joro@8bytes.org, 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, akpm@linux-foundation.org, treding@nvidia.com, dwmw2@infradead.org, iamjoonsoo.kim@lge.com, linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP 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 afe5a673668e..71aba1551275 100644 --- a/kernel/dma/contiguous.c +++ b/kernel/dma/contiguous.c @@ -186,14 +186,23 @@ int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base, * 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)) {