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 D7663C4363A for ; Mon, 5 Oct 2020 13:43:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8F5E020774 for ; Mon, 5 Oct 2020 13:43:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="bkv55xe1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726329AbgJENn3 (ORCPT ); Mon, 5 Oct 2020 09:43:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60506 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725932AbgJENn2 (ORCPT ); Mon, 5 Oct 2020 09:43:28 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7A164C0613CE; Mon, 5 Oct 2020 06:43:27 -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=jb5thMIWpCkZBAm0OYkNTxcNM8PY6DURu7qCjd3L9nk=; b=bkv55xe1/G1SaZg+Ki7iWQKwNR q8pgQvSNPgTwrzZxa/2xHHL4iU/JMWqKDRv9YuDcofZCD/4sWqrHThuvXBIf7sQCuDueV/8S44IRX cxYlin4+qU9S89E46tk/MJi8AbJ4UfpX4kmKp7wqxlCKTL3zZPVgZeMXsG6iYTcZg8elDF5PxhZ3R 1r5zkb7G90HwjOn8IgV1W0RjFGGyj9UJEDQL2ElR5OvwiYtdB/rJM1FYNZyQlx7FMhao5LjUlTEUt 3J4xUsRlz/Ve3ANIK35psd/rrvf5nkqNcjucSAmcJFOThsz0t7dZtOng+nHYjhQT2gP/XmZmmRz3q 8WvWI+Kw==; Received: from hch by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kPQls-00031f-0l; Mon, 05 Oct 2020 13:43:20 +0000 Date: Mon, 5 Oct 2020 14:43:19 +0100 From: Christoph Hellwig To: "Martin K. Petersen" Cc: Naohiro Aota , linux-btrfs@vger.kernel.org, dsterba@suse.com, hare@suse.com, linux-fsdevel@vger.kernel.org, Johannes Thumshirn Subject: Re: [PATCH v8 01/41] block: add bio_add_zone_append_page Message-ID: <20201005134319.GA11537@infradead.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Fri, Oct 02, 2020 at 09:39:04AM -0400, Martin K. Petersen wrote: > > Naohiro/Johannes, > > > Add bio_add_zone_append_page(), a wrapper around bio_add_hw_page() which > > is intended to be used by file systems that directly add pages to a bio > > instead of using bio_iov_iter_get_pages(). > > Why use the hardware limit? For filesystem I/O we generally use the > queue soft limit to prevent I/Os getting too big which can lead to very > unpredictable latency in mixed workloads. > > max_zone_append_sectors also appears to be gated exclusively by hardware > constraints. Is there user-controllable limit in place for append > operations? Zone Append operations can't be split, as they return the first written LBA to the caller. If you'd split it you'd now need to return multiple start LBA values.