From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-68.mta0.migadu.com [91.218.175.68]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AB100438490 for ; Wed, 30 Sep 2026 08:42:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.68 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790757764; cv=none; b=R3RkQcr1XcwvnNhnzTuDcalkljfroefX9DQUB4VlrRMbLt+2YYAeU4laQCMsGaeJAWd5qC15bAtu7NeKY/s+8+7zw2gSOVV2pv+maxVMhQe4RKcwCslHIJlW2PQe+t3a3vgNrmsmIgAIAdPV/j2ORgHt4ld3KX6OPkh2/FV62Bk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790757764; c=relaxed/simple; bh=i1uEsvgICh0DhCFYrmgloUbKJNENOBFuqjKtshnFzJE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Z8Q4okE583FCJBYbqCkNRW1J9D0awcCtIZt8frwktnUsHAhW0wZG3DexeWfUyYoxtS5BXH3gOU9oPLbXDCekrHOKv9LCCbgUljWNNc4FT9tNvqy1KTnvFp69lYYd3nlcJJaMd3AEhc2zNxMQ5YLP6ucPiDzh5ROJjhhMhIFjm5A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=OFx0gwwK; arc=none smtp.client-ip=91.218.175.68 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="OFx0gwwK" X-Envelope-To: linux-xfs@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=i1uEsvgICh0DhCFYrmgloUbKJNENOBFuqjKtshnFzJE=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1790757759; v=1; x=1791362559; b=OFx0gwwKcjPyTLi5Ajr7FGIyko98bIFpQue6mXKWBOHsKJpXPmeFqnUjQn7W2LIX0HFO7GtT UVvtnKoJhyrIsV1QX69HG2Y0GAx5D9aq8wbBQt/DSY3ObtH/cvLnEAvM9Qc7XK3RqASV7jrzgC3 s1LYj2zXXZ4W1Fn1qMli1TUo= X-Envelope-To: linux-xfs@vger.kernel.org Received: by mta10.migadu.com with ESMTPS id 4d978d09c79ff881; Wed, 30 Sep 2026 08:42:39 +0000 X-Mizu-Trace-ID: 4d978d09c79ff881 X-Migadu-Flow: FLOW_OUT Message-ID: <29380cd8-19f5-4ae7-bdb7-b7908decb474@linux.dev> Date: Wed, 30 Sep 2026 09:42:34 +0100 Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] xfs: don't limit software atomic writes by the group alignment To: "Pankaj Raghav (Samsung)" Cc: Pankaj Raghav , cem@kernel.org, linux-xfs@vger.kernel.org, John Garry , "Darrick J . Wong" , gost.dev@samsung.com References: <20260925103640.932735-1-p.raghav@samsung.com> <41749fa7-dcfa-46f0-af0f-ed3fa5f39f15@linux.dev> <050f7a77-9c0e-4cab-8ddb-6932b885e12f@linux.dev> Content-Language: en-US From: John Garry In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 9/30/26 06:10, Pankaj Raghav (Samsung) wrote: >>> Just to give more context: >>> >>> Trace of calc_atomic_write_unit_max: >>> >>>  mount-696   [010]   449.230543: xfs_calc_atomic_write_unit_max: dev >>> 259:0 ag max_write 262144 max_ioend 512 max_gsize 134217728 awu_max 512 >>> >>> 2097152 comes from awumax being 512 fsblocks. >>> >>> root@debian:~# xfs_info /dev/nvme0n1 >>> meta-data=/dev/nvme0n1           isize=512    agcount=8, >>> agsize=268435455 blks >> >> Well max power-of-2 factor of this is going to be 1. >> > > Exactly. I get that we should restrict max_opt to be 1 because the AG's > will not be aligned and the best we can do is one fsblock for HW based > atomics. Why should we restrict the max (SW atomics limit) to 1 fsblock? > Maybe in this case we don't need to restrict CoW-based atomics to 1 fsblock. But why care? I mean, you have HW support, which is so much better to use than CoW-based atomics, so better to config your FS to avail of them.