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 5082CC433E2 for ; Thu, 17 Sep 2020 14:54:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C27DE22241 for ; Thu, 17 Sep 2020 14:54:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="u5AXJ9qO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727666AbgIQOw7 (ORCPT ); Thu, 17 Sep 2020 10:52:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33724 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727665AbgIQOtY (ORCPT ); Thu, 17 Sep 2020 10:49:24 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 06854C06174A; Thu, 17 Sep 2020 07:48:12 -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=r6XGbhkzldwBJ9zbZcUG3CmtGLSS9SRTWvvxIUYsiWw=; b=u5AXJ9qOmy9oveddJWSUS6AkdN HTLBxtBBnUbdLyOLCh38/tVeqla5BwBRjLWIJ5YKzeBApwbBZCO/P+YC6CQU9PY0ikP7StLyoFcFq 6sR8dt4Mw1xym36Oi5bpSPG4r/XLs4CqPHBws1IV48wJwwKrBhOYze8ZYQh+1bn9Aa9ZcgytUgfh4 r3aoE8tGeEJB4z0qHfgIXkpb4Z9r33qyXkHaD3t+IDsSP/RNBsaYy+yL+klKTn9G/QL0m3DC4yGFZ ec1mMgCNkY3VBuDYQN+5vP//SnX7hAVnBGazq2OxvFS43ve6Vdrq1dvz8CAEi+VL4ln5pBXmJ1syi zmv8GMXA==; Received: from hch by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kIvCe-0008CS-42; Thu, 17 Sep 2020 14:48:04 +0000 Date: Thu, 17 Sep 2020 15:48:04 +0100 From: Christoph Hellwig To: Brian Foster Cc: Christoph Hellwig , "Darrick J. Wong" , Dave Chinner , Ritesh Harjani , Anju T Sudhakar , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, willy@infradead.org, minlei@redhat.com Subject: Re: [PATCH] iomap: Fix the write_count in iomap_add_to_ioend(). Message-ID: <20200917144804.GA31389@infradead.org> References: <20200824142823.GA295033@bfoster> <20200824150417.GA12258@infradead.org> <20200824154841.GB295033@bfoster> <20200825004203.GJ12131@dread.disaster.area> <20200825144917.GA321765@bfoster> <20200916001242.GE7955@magnolia> <20200916084510.GA30815@infradead.org> <20200916130714.GA1681377@bfoster> <20200917080455.GY26262@infradead.org> <20200917104219.GA1811187@bfoster> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200917104219.GA1811187@bfoster> 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 Thu, Sep 17, 2020 at 06:42:19AM -0400, Brian Foster wrote: > That wouldn't address the latency concern Dave brought up. That said, I > have no issue with this as a targeted solution for the softlockup issue. > iomap_finish_ioend[s]() is common code for both the workqueue and > ->bi_end_io() contexts so that would require either some kind of context > detection (and my understanding is in_atomic() is unreliable/frowned > upon) or a new "atomic" parameter through iomap_finish_ioend[s]() to > indicate whether it's safe to reschedule. Preference? True, it would not help with latency. But then again the latency should be controlled by the writeback code not doing giant writebacks to start with, shouldn't it? Any XFS/iomap specific limit also would not help with the block layer merging bios.