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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, T_DKIMWL_WL_HIGH 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 BE64FC43218 for ; Tue, 11 Jun 2019 06:17:29 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 951D62086A for ; Tue, 11 Jun 2019 06:17:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="BsrV4KaC" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 951D62086A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=arHrarGs7E1w+bcwVO7x7GfIsjvvb+740IVHtvHvnlg=; b=BsrV4KaCPbxRKq A482SzskHl2LwDo2nWdqIrNVZSIph4t+A2VOC2YOLveMnhMANUka3aDVljBpPCGTiBU6tCBf+MZLM OEfHtTWtjfNlalgP7Q7b4+MxoV0e/npmqeSUbxLEwEO8Dm6j3P/srWoICPNvHECkXTFTpgqFoR7Nn mMG3/fJnRm2KUSRfjFZSg7ASovH+aBX2ixbk2tk8RS+4c+zbtoiTUInMnnsqPvWWnbNC0vZt7pq/+ KGsnnPcjKmLlqBcN9autXptnRsRcVn9XqHxguK4SPtRRU+6amKkcLl+1TVFTgm+VHPMj/DO62EFa8 4xbzh0P+AWs1+oktwuHQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1haa62-00089q-QA; Tue, 11 Jun 2019 06:17:26 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1haa5z-00089V-Ry for linux-arm-kernel@lists.infradead.org; Tue, 11 Jun 2019 06:17:25 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 04483344; Mon, 10 Jun 2019 23:17:22 -0700 (PDT) Received: from [10.162.43.135] (p8cg001049571a15.blr.arm.com [10.162.43.135]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 847F13F73C; Mon, 10 Jun 2019 23:17:20 -0700 (PDT) Subject: Re: [PATCH 4/4] mm/vmalloc: Hugepage vmalloc mappings To: Nicholas Piggin , Mark Rutland References: <20190610043838.27916-1-npiggin@gmail.com> <20190610043838.27916-4-npiggin@gmail.com> <20190610141036.GA16989@lakrids.cambridge.arm.com> <1560177786.t6c5cn5hw4.astroid@bobo.none> From: Anshuman Khandual Message-ID: Date: Tue, 11 Jun 2019 11:47:39 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <1560177786.t6c5cn5hw4.astroid@bobo.none> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190610_231723_944592_97CEDE1D X-CRM114-Status: GOOD ( 12.84 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 06/10/2019 08:14 PM, Nicholas Piggin wrote: > Mark Rutland's on June 11, 2019 12:10 am: >> Hi, >> >> On Mon, Jun 10, 2019 at 02:38:38PM +1000, Nicholas Piggin wrote: >>> For platforms that define HAVE_ARCH_HUGE_VMAP, have vmap allow vmalloc to >>> allocate huge pages and map them >>> >>> This brings dTLB misses for linux kernel tree `git diff` from 45,000 to >>> 8,000 on a Kaby Lake KVM guest with 8MB dentry hash and mitigations=off >>> (performance is in the noise, under 1% difference, page tables are likely >>> to be well cached for this workload). Similar numbers are seen on POWER9. >> >> Do you happen to know which vmalloc mappings these get used for in the >> above case? Where do we see vmalloc mappings that large? > > Large module vmalloc could be subject to huge mappings. > >> I'm worried as to how this would interact with the set_memory_*() >> functions, as on arm64 those can only operate on page-granular mappings. >> Those may need fixing up to handle huge mappings; certainly if the above >> is all for modules. > > Good point, that looks like it would break on arm64 at least. I'll > work on it. We may have to make this opt in beyond HUGE_VMAP. This is another reason we might need to have an arch opt-ins like the one I mentioned before. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel