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=0.2 required=3.0 tests=BAYES_50,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 CD636C2D0E2 for ; Tue, 22 Sep 2020 12:28:45 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (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 3A41A2396D for ; Tue, 22 Sep 2020 12:28:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="J8vJB8PG" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3A41A2396D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvdimm-bounces@lists.01.org Received: from ml01.vlan13.01.org (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 983F214840A6D; Tue, 22 Sep 2020 05:28:43 -0700 (PDT) Received-SPF: None (mailfrom) identity=mailfrom; client-ip=2001:8b0:10b:1236::1; helo=casper.infradead.org; envelope-from=willy@infradead.org; receiver= Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 2E03D1481D09D for ; Tue, 22 Sep 2020 05:28:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=QOf2JTCyG7BLU81U37VjbgSKPGgWOzBrM3G1telCsN0=; b=J8vJB8PGDvNZr3pL6E5VUXs5mh 7fhLdUsaxmKF5Q9VJEZoijpH3ddlo7CWLkRQyXc1cLv2C71vR5gsRKL2y+6Iil1ZlrXoZtpcokWZV /sViwtrr/gn3EPRdVP6nrwsLDb4Tc3+Bw1MbQjXodXO2uI6uCmMvGItmnJ1PMckk2naxTYXBelE9m BMheLjIYQiDNYHDQXPLDCJjsG/BRqimL/XtZph1DC1ZOKp9PoNiWLuWglCamn3s2nsUiTjnkFP6HE ijBWNZGs3y0YPF32Hf/NaucqXzpCPa+DAMfw8XmcB+1xqcHmO5oxGSNupyWkbzyg4ooEVZnbICIsw SUOOZ2rg==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kKhP9-0000rB-4w; Tue, 22 Sep 2020 12:28:19 +0000 Date: Tue, 22 Sep 2020 13:28:19 +0100 From: Matthew Wilcox To: Mikulas Patocka Subject: Re: NVFS XFS metadata (was: [PATCH] pmem: export the symbols __copy_user_flushcache and __copy_from_user_flushcache) Message-ID: <20200922122819.GD32101@casper.infradead.org> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Message-ID-Hash: SGAP4L657MIVXSPE5VYTSUFD66MSJCZQ X-Message-ID-Hash: SGAP4L657MIVXSPE5VYTSUFD66MSJCZQ X-MailFrom: willy@infradead.org X-Mailman-Rule-Hits: nonmember-moderation X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation CC: Linus Torvalds , Alexander Viro , Andrew Morton , Jan Kara , Eric Sandeen , Dave Chinner , "Tadakamadla, Rajesh (DCIG/CDI/HPS Perf)" , Linux Kernel Mailing List , linux-fsdevel , linux-nvdimm X-Mailman-Version: 3.1.1 Precedence: list List-Id: "Linux-nvdimm developer list." Archived-At: List-Archive: List-Help: List-Post: List-Subscribe: List-Unsubscribe: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Mon, Sep 21, 2020 at 12:20:42PM -0400, Mikulas Patocka wrote: > The same for directories - NVFS hashes the file name and uses radix-tree > to locate a directory page where the directory entry is located. XFS > b+trees would result in much more accesses than the radix-tree. What? Radix trees behave _horribly_ badly when indexed by a hash. If you have a 64-bit hash and use 8 bits per level of the tree, you have to traverse 8 pointers to get to your destination. You might as well use a linked list! _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org