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=-3.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,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 388CCC433DF for ; Mon, 12 Oct 2020 16:45:53 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 DB2E620838 for ; Mon, 12 Oct 2020 16:45:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="eYiCO6En"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="cjGmRDHB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DB2E620838 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-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.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:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=aqgfOgCoft190azbzcIw95QKxW8ke7v8HXjD6Qxnvu0=; b=eYiCO6En+MC2DbciwpPduZfKU tNLobAW9cUB1YZ9s1pnY8gFUqCVQxrFAsjslExTPzuuF8IWDj55RvnYLYtuFzO1Hhpisb1OAiIMR2 yJWrrWwl6Q4KPxbG9FRoRLm0O/47Ty6/ZwlOxM1cXcR5q8ggoaETa/uSH/1VNN1m2EpmjHlyf5FYi EsLrMzCsXoThKxAGAxNfb2IeRnYwL4uhkwqw0bCDMe9N66Cdo+IgzZz4NJ1JSkeVW9E2xkmyb/sQt 561Ux6mW8I17aJfTrWl3POEP7n9M0nstEGwfklGEKtUiWzTie/ZlvyY/NjwelnSmyzv2bpID+52K2 fKDB7FgkA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kS0wG-0006XW-Iz; Mon, 12 Oct 2020 16:44:44 +0000 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kS0wF-0006XG-Lx; Mon, 12 Oct 2020 16:44:43 +0000 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=l9dol8BjF52rFe8mzz85c9RZmeAYDZ2M1zPXpY3Bxec=; b=cjGmRDHB+K+xo1zaI46uR/JWZM mu6b6OfRoAYfgdNA5Kf5Iurex6D1FcBZ+mRQhj12vLi3isoy7f1JrMIQOIfa61TejqqWEwpL43yKb 2mAeiG7QIg8Vb+ajA0gepoKbc6o17WQEzV+UWJKTyQWQStoFHb/kNJEfYbWmPc27vxrcwV1GpTL/g cqcPit9vRB3f1Zs6upmREd44qhzYUWIO5sf13vXmWctx364S7GYQlJM4ZaGSBTPIwUKM8imQUHEl+ YU7Gj26Vo02zH0C4u7a3/EscApIpoLOe+KQejmiwTcRHTR/bJWdX/slhogDIyA7BDVBafjowKFz4j 1dyYxPzg==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kS0wA-0004gO-8Q; Mon, 12 Oct 2020 16:44:38 +0000 Date: Mon, 12 Oct 2020 17:44:38 +0100 From: Matthew Wilcox To: Dave Hansen Subject: Re: [PATCH RFC PKS/PMEM 22/58] fs/f2fs: Utilize new kmap_thread() Message-ID: <20201012164438.GA20115@casper.infradead.org> References: <20201009195033.3208459-1-ira.weiny@intel.com> <20201009195033.3208459-23-ira.weiny@intel.com> <20201009213434.GA839@sol.localdomain> <20201010003954.GW20115@casper.infradead.org> <20201010013036.GD1122@sol.localdomain> <20201012065635.GB2046448@iweiny-DESK2.sc.intel.com> <20201012161946.GA858@sol.localdomain> <5d621db9-23d4-e140-45eb-d7fca2093d2b@intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <5d621db9-23d4-e140-45eb-d7fca2093d2b@intel.com> X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-aio@kvack.org, linux-efi@vger.kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, Peter Zijlstra , linux-mmc@vger.kernel.org, Dave Hansen , dri-devel@lists.freedesktop.org, linux-mm@kvack.org, target-devel@vger.kernel.org, linux-mtd@lists.infradead.org, linux-kselftest@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, Ira Weiny , Thomas Gleixner , drbd-dev@lists.linbit.com, devel@driverdev.osuosl.org, linux-cifs@vger.kernel.org, linux-nilfs@vger.kernel.org, linux-scsi@vger.kernel.org, linux-nvdimm@lists.01.org, linux-rdma@vger.kernel.org, x86@kernel.org, amd-gfx@lists.freedesktop.org, linux-afs@lists.infradead.org, Eric Biggers , Ingo Molnar , intel-wired-lan@lists.osuosl.org, kexec@lists.infradead.org, xen-devel@lists.xenproject.org, linux-ext4@vger.kernel.org, bpf@vger.kernel.org, Dan Williams , Fenghua Yu , intel-gfx@lists.freedesktop.org, ecryptfs@vger.kernel.org, linux-um@lists.infradead.org, reiserfs-devel@vger.kernel.org, linux-block@vger.kernel.org, linux-bcache@vger.kernel.org, Borislav Petkov , Andy Lutomirski , Jaegeuk Kim , ceph-devel@vger.kernel.org, io-uring@vger.kernel.org, linux-cachefs@redhat.com, linux-nfs@vger.kernel.org, linux-ntfs-dev@lists.sourceforge.net, netdev@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, samba-technical@lists.samba.org, linux-kernel@vger.kernel.org, cluster-devel@redhat.com, linux-fsdevel@vger.kernel.org, Andrew Morton , linux-erofs@lists.ozlabs.org, linux-btrfs@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-mtd" Errors-To: linux-mtd-bounces+linux-mtd=archiver.kernel.org@lists.infradead.org On Mon, Oct 12, 2020 at 09:28:29AM -0700, Dave Hansen wrote: > kmap_atomic() is always preferred over kmap()/kmap_thread(). > kmap_atomic() is _much_ more lightweight since its TLB invalidation is > always CPU-local and never broadcast. > > So, basically, unless you *must* sleep while the mapping is in place, > kmap_atomic() is preferred. But kmap_atomic() disables preemption, so the _ideal_ interface would map it only locally, then on preemption make it global. I don't even know if that _can_ be done. But this email makes it seem like kmap_atomic() has no downsides. ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/