From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A2158B65C; Mon, 2 Jun 2025 05:07:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748840821; cv=none; b=KFqxg3+ydIxUXjysvh6jYqb5ynXbPkv3q2k6qjVDzV5NazSPuLdbBW1bkvWkVHiULxG4BAVNt4oWO+InBRNaUa7Tmqz7V01o5da+VozYs74WjNV+3cqewmRO/9hQHuXUaG3cCDMfY+tkZoHTm6yDSQs4Pe4YFcTzWphj9ae0RqQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748840821; c=relaxed/simple; bh=KBKvwrDtYOGJ3Sk5yGhweAEu1h06hJFpfgpPkIk4B3s=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=S+VT8YHOQ+0PGMcnfwv8ZvKH5OIjAMMaFgl/F0mNy/UJZ0Avs/DzIUmRkR8QDKCvU5xt86qBuOoUB8IIKnkgdsVeCMrcCLAfdbH7+sspEcwr6I0IGv5fRoqMNN8oRGTmOMDfLBN5U+h5QNdzEsnQxDKi+bb0G4EVYjbGiXwmhs8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=ijXA5isb; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ijXA5isb" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; 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=NryE9w5TNLfeM9L423ZI0Ib2QmGLwnVsc7lYeYfK/a0=; b=ijXA5isbaSV32frPGbUYV6bFoW Jgw8OAs/CGM9sZ6jTZ9WnV8EEoj50QIJyrW2RLGsGmcH7vdJC2jgckvR/ApdiCliut4vOj7KVFn0O Vr+PgdL/JUEkphrDeAhCOKjGKErQd4MBUoZxPZq8OcK/c7sDvqh1SunI1BnsRTC7bYhH6ag4BZIyr 5KELzdzI/7Z0TRsihqgJDD995ElXAaazpVb75QZpvv92GWjzyoPgQ0VXCA+OIgrdgS4Cm0f89LoGE uWWlqemjLPrVW+WN/Xu+FE46+ojzVw/sXCn9VycImvhFwWDiz9/hWR13ivBF7iLXKmYBo2xO71AKP D+4HpW3w==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uLxO0-00000006jDe-19rD; Mon, 02 Jun 2025 05:07:00 +0000 Date: Sun, 1 Jun 2025 22:07:00 -0700 From: Christoph Hellwig To: "Darrick J. Wong" Cc: Christoph Hellwig , zlang@redhat.com, fstests@vger.kernel.org, linux-xfs@vger.kernel.org Subject: Re: [PATCH 3/4] xfs/259: try to force loop device block size Message-ID: References: <174786719374.1398726.14706438540221180099.stgit@frogsfrogsfrogs> <174786719445.1398726.2165923649877733743.stgit@frogsfrogsfrogs> <20250528222226.GB8303@frogsfrogsfrogs> Precedence: bulk X-Mailing-List: fstests@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250528222226.GB8303@frogsfrogsfrogs> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Wed, May 28, 2025 at 03:22:26PM -0700, Darrick J. Wong wrote: > Welll... the only reason I patched the loop driver to turn ovn directio > by default is because writeback throttling for loop devices keeps > getting turned on and off randomly. At this point I have NFI if > throttling is actually the desired behavior or not. It makes fstests > crawl really slowly. > > On one hand it seems bogus that a loopbacked filesystem with enough > dirty pages to trip the thresholds then gets throttled doing writeback > to the pagecache of the loop file, but OTOH it /is/ more dirty > pagecache. Ultimately I think non-directio loop devices are stupid > especially when there are filesystems on top of them, but I bet there's > some user that would break if we suddenly started requiring directio > alignments. > > Maybe RWF_DONTCACHE will solve this whenever it stabilizes. Well, I'm all for using direct I/O loop devices by default. But having non-standard kernel hacks for that is pretty silly. Can we just make xfstests use direct I/O by default so that everyone uses the same configuration?