From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 7EFB02DEA7E; Tue, 12 Aug 2025 07:53:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754985239; cv=none; b=b+VkrowRwHxAnt5gPWTV17oIZWKUp+K8j0/vdrd9ua5u/nYalXMIOtnwbHtfTOh40KJySg77JNPfVu5sOe9NEo0jwEDGjcVrRhCuvKA2RoHCl6Fo4080EcOrXjKryAb5vPS6BARiM05PndPDyfUjsiNjPiQeNyhYGlBN9TwkdOE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754985239; c=relaxed/simple; bh=sw8wLAIZdKxUOMDtddxEFYfkLyHWxf/hNcZfBt9jddc=; h=Message-ID:Date:MIME-Version:Cc:Subject:To:References:From: In-Reply-To:Content-Type; b=cJ2PDMOiukMMiREvCC00uR6G7dwvM9VYKim5ywz/jKlqUPHlmBv5hoFB7rkamJMNmLWxOgpzeFgpflZLGnEwILMKJWyhZSupby+1DN7aADANRKQsXtycCxqB5MZJnJndTMDBQVmPe54hW1Wrpu2HocwQSPrVCIIKr3MLkczaj5I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jh3uStF3; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="jh3uStF3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9B358C4CEF0; Tue, 12 Aug 2025 07:53:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1754985239; bh=sw8wLAIZdKxUOMDtddxEFYfkLyHWxf/hNcZfBt9jddc=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=jh3uStF3r13oKRFs0sLYrM2446Mi+VB8hpHKE9Zh83l99O+usPogtPFDkMn9Q5GM1 ulEPEVxJhe/iJdSxhpCcEs7THsZMAfxFmWt0cASdTay3BP6NgUC5bXq3e2Rj5NUrH3 AGUweTGCW+hwhMuQ9gFmRjR9UW5kyJq9d1bhq5qBCtDVf150CeQW15gSD+CjZxwgWg U4heXQ0DgqonUyh78GfP/hhONpJOUWjPBxp1Gl0afR5DNOMx7QCTJT0ecG+2n5k9EB zJS5Y+vwsB//qSKw/W1Zb4OfmVnzGQiXWwtqp5AciGajSdR1iXRJwT6y+ZMP7hxh/Q DEBA8uRrQMeEQ== Message-ID: Date: Tue, 12 Aug 2025 15:53:54 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: chao@kernel.org, jaegeuk@kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org Subject: Re: [PATCH v3] f2fs: introduce flush_policy sysfs entry To: Christoph Hellwig References: <20250807034838.3829794-1-chao@kernel.org> Content-Language: en-US From: Chao Yu In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/12/25 15:32, Christoph Hellwig wrote: > On Tue, Aug 12, 2025 at 02:28:46PM +0800, Chao Yu wrote: >> BTW, I suffered extremely long latency of checkpoint which may block every >> update operations when testing generic/299 w/ mode=lfs mount option in qemu, >> then I propose to use PREFLUSH instead of FUA to resolve this issue. >> >> "F2FS-fs (vdc): checkpoint was blocked for 24495 ms" >> >> I just realize that using cache=directsync option in qemu can avoid FUA hang >> issue, anyway, let me test more w/ this option. > > Well, for decent qemu performance you always want to use DIRECT I/O. > directsync is generally not a very good idea as it forces every write > to be synchronous and will give you very bad performance. Yeah, I think that may hurt the performance too, at least, I don't see any obvious change for time cost of generic/299 testcases, but still I need to run all my testcase to see what will happen. :) generic/299 115s ... 113s > > What did you use before? At least for older qemu the default was > buffered I/O, which can lead to very expensive fua or flush calls. Previously, I didn't use any cache= option, as manual described, it should equal to cache=wrteback. Thanks,