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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 DFD62C4363D for ; Wed, 23 Sep 2020 15:04:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 868A821D7D for ; Wed, 23 Sep 2020 15:04:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="MkYEExTq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726749AbgIWPEp (ORCPT ); Wed, 23 Sep 2020 11:04:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38804 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726516AbgIWPEo (ORCPT ); Wed, 23 Sep 2020 11:04:44 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C4AC5C0613CE; Wed, 23 Sep 2020 08:04:44 -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=Ose8ctZCTv8oUOd9k3tTT76nITLXgVZlsCte1r4Sf9c=; b=MkYEExTq1+wkaz83zMuspp5RjA Ql+JlgSLUtPgJQMk5ZRNIO+I2UvxTYWBAkIXlCxSLKN0kKXI86QBoGjW7A+yKUpkqMuuehrinsPuf iwX4oT+QNjApAyJGa8cH3EwMkixriTNBrfTFPhwDoOaCloAwyeLBZpcBeXr6ULKd7x6mz/VU1mrTF rjgPBXE/KVXkfXpLPhqrWyo99AM+ADFVOdaGRg6A3iJrv8o6ovKyridoI1mwkForkyoK8bF8rFGrw fd8w+PRxzla1bKvhyrYdLqm3AOmAqwCzB8te5Y2Zk6g0lBF64zMFMDuAmKdoz1JjyoTd9K7oNNJHv KnkoQvSQ==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kL6Jn-0005Kf-EE; Wed, 23 Sep 2020 15:04:27 +0000 Date: Wed, 23 Sep 2020 16:04:27 +0100 From: Matthew Wilcox To: Mikulas Patocka Cc: Jan Kara , Dave Chinner , Dan Williams , Linus Torvalds , Alexander Viro , Andrew Morton , Vishal Verma , Dave Jiang , Ira Weiny , Eric Sandeen , Dave Chinner , "Kani, Toshi" , "Norton, Scott J" , "Tadakamadla, Rajesh (DCIG/CDI/HPS Perf)" , Linux Kernel Mailing List , linux-fsdevel , linux-nvdimm Subject: Re: NVFS XFS metadata (was: [PATCH] pmem: export the symbols __copy_user_flushcache and __copy_from_user_flushcache) Message-ID: <20200923150427.GP32101@casper.infradead.org> References: <20200922050314.GB12096@dread.disaster.area> <20200923095739.GC6719@quack2.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 23, 2020 at 09:11:43AM -0400, Mikulas Patocka wrote: > I also don't know how to implement journling on persistent memory :) On > EXT4 or XFS you can pin dirty buffers in memory until the journal is > flushed. This is obviously impossible on persistent memory. So, I'm > considering implementing only some lightweight journaling that will > guarantee atomicity between just a few writes. That's a bit disappointing considering people have been publishing papers on how to do umpteen different variations on persistent memory journalling for the last five years. https://www.google.com/search?q=intel+persistent+memory+atomic+updates for example