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 0493A1A9FA6; Tue, 12 Aug 2025 07:32:26 +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=1754983948; cv=none; b=UE4XFBN6s+H5V54zwh0ZL5FvQkn2imQn85y4P3/vEV5Akg1/BM/ijvMmw7wuWCMPiE9RYBApkCRvmLsUlFU31vdTY7yPD2JHmrFjD/Jus+DHYnJ6m80TZtHJr9idx0WEi7W4iIdXB0rRRborwGgnLg2C4OzdaQ+zGtwPu+VYcmw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754983948; c=relaxed/simple; bh=AZ/oY/KvkfRoCBhJNzaxhzPts3cxjqP8EDlJrLC8eZ0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=VbNOjiWOfwiid0CY8ohMEu5VwvYgSTiNByDVgQhEpG5RJimFs98ZOUUIwM2Zrb8TiLAFB+z031x42jeyK6QTn8GENkUoyC4IILrnt9wMd5F3ENBlmf7e3uBYg13Lo2NbZY7kjsj0rGwE/IgkIF0Gq0a24P2dnTvYchsMYBcCDMg= 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=vWA+OhBm; 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="vWA+OhBm" 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=2nTia5ts+VjOnB6KoRPEICX8cfIqCEHm8VoqRMMJHVw=; b=vWA+OhBmwsieByOdybHKj1jR8X B8uftFHEs/UuURKKK4pGRkm9G1XUtLiibtdrtoYkFkZNieGxYAmSJYjJ0An2Pg3g99rLGPAykba/w Yr7V6Nor4CW62aekr3V1/p8UerLCqCwI2GhWZkN71vpVUgT0bADtVPAdw9Bjn36tkjoonq/PMdDHU KJ4FhNQ8rJQBNmdYLbU/MkL2+JvafMVTZvEVG22gSPApuBkC1FRkc5dfle7yUxSR01HqQ/D/FUX3k YLsqaY7Whf6fbv28qTRrUMYa3uvexemuKv5+q8BWgNUR5En9pA346hDSxP4AiShOQnnrsFoZkdWKA 2iuVRLcw==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uljUg-0000000A7cu-01q7; Tue, 12 Aug 2025 07:32:26 +0000 Date: Tue, 12 Aug 2025 00:32:25 -0700 From: Christoph Hellwig To: Chao Yu Cc: Christoph Hellwig , 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 Message-ID: References: <20250807034838.3829794-1-chao@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@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: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html 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. 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.