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 6ED461F91C5; Mon, 3 Feb 2025 08:06:47 +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=1738570009; cv=none; b=bAn+A39xc+AD1lY6dBmomQyHYOsMvYmbil7DQHbph1vM6etUSkKZdSVB3KiWJgQ8U56iU9TMV9sKz1Z7tcxztfzw0fnQnrjT6HHEJiEJ8Ndoge8Qx6kgYamAqwv6Uo10Zll2ZQjKW5EjZkQbQjEY86/+PCGrHBfQQfZRRp0k5s4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738570009; c=relaxed/simple; bh=9f6Ab6tq2/THWPNFqctaV85Q+DUkFgaVBJK6UYBOMrc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=J3zbgd73iJFfquqyUfawn8aB5RFc/D9bPMKlIqNZAqqzRpWdX8osOManRrTLj2DMdp5GDka3y/O0rk3kDSY6YeqVL5m/zUt9p4q7014uI4Q+MPmwjs5rRropcT3mJ1xUfMgv9swv7cDBuoW670Cc8+39jjHqOPRRCfCyeL8LTcs= 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=yZWM63HM; 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="yZWM63HM" 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=r1r6plQaRoAy1Nxbdg0BWrNM7QAkG9cm/NIMqGIem9Y=; b=yZWM63HMplkQd9jjGoEVajgvTU wk8XerzMhuuMUkMYuQFTrHN2AqJnjAdGFrJyqqHip67hvx3XcNfqMIheNLk4Y+So9JSf3CBMhoTZy PT4r+CCYZiuEUUR9m80LQ18o+Hccuv9YrCjM/PAaC+I6wUmVYQcoPO2GqDO8vWfMrYBfqU8PIq5j9 8T8iu5JGjnyT+bzTbobALbTCdOVWui2CkTLCc6Dw5Fd6nLE07M3osVSuvUc9kbG+i3pdTGC7RhxxK H5NA2DFwsybhY4mmSg5fDtNVeBqP/ANf9VBd/x79Wy8GXn8qCIx6G9Qvi/7oBse1sUkc90Vs2MpHa WlLeJ+2Q==; Received: from hch by bombadil.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1terTh-0000000ElsK-1hgZ; Mon, 03 Feb 2025 08:06:45 +0000 Date: Mon, 3 Feb 2025 00:06:45 -0800 From: "hch@infradead.org" To: Johannes Thumshirn Cc: "hch@infradead.org" , Kanchan Joshi , Theodore Ts'o , "lsf-pc@lists.linux-foundation.org" , "linux-btrfs@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-nvme@lists.infradead.org" , "linux-block@vger.kernel.org" , "josef@toxicpanda.com" Subject: Re: [LSF/MM/BPF TOPIC] File system checksum offload Message-ID: References: <20250130091545.66573-1-joshi.k@samsung.com> <20250130142857.GB401886@mit.edu> <97f402bc-4029-48d4-bd03-80af5b799d04@samsung.com> Precedence: bulk X-Mailing-List: linux-block@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 Mon, Feb 03, 2025 at 08:04:42AM +0000, Johannes Thumshirn wrote: > Well for the WAF part, it'll save us 32 Bytes per FS sector (typically > 4k) in the btrfs case, that's ~0.8% of the space. It saves you from the cascading btree updates. With nocow this could actually allow btrfs to write with WAF=1 for pure overwrites. But even with data cow it will reduce a lot of churn, especially for O_SYNC writes.