From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (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 EF0E1849C for ; Thu, 21 Nov 2024 04:57:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.95.11.211 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732165041; cv=none; b=pfVhipxLpvE0JgimvxcH0657Kysh9RDKKSgIt/aCNL/Gbtj171izZRpbWfM8nVCphtKB+g1YrP1qzbjlczTEFNhYbYBkSlcFbN8b6il1KCUItXSrVipProiQ0w/ZzBxyaI4HiWKkVhEuFHPBmnHzyZhlr0JDeMfvOhIEY47ln8Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732165041; c=relaxed/simple; bh=6Z2AU7YhC5tmjXwQ88AWETqN0BUdsHTSCxuB7Ig9lkU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JcxPp5DJAAt30ty8BBTxgDgFwZQleFQh0e631WBJguNKteM9ZmWimaxAY40mYhKf+PWVKZ1QMtlRqmTSdQivgha23N7nGIaTzKcoHyzRitD6mjc3JlVZov0+pjPl3RFa4Osp5drglyhzXOQzl7uVqgjLp+ctBoIC6lWl1CoFzCE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de; spf=pass smtp.mailfrom=lst.de; arc=none smtp.client-ip=213.95.11.211 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lst.de Received: by verein.lst.de (Postfix, from userid 2407) id CC6E968BEB; Thu, 21 Nov 2024 05:57:14 +0100 (CET) Date: Thu, 21 Nov 2024 05:57:14 +0100 From: Christoph Hellwig To: Jens Axboe Cc: Chaitanya Kulkarni , Saeed Mirzamohammadi , "linux-kernel@vger.kernel.org" , "linux-nvme@lists.infradead.org" , Ramanan Govindarajan , Sagi Grimberg , Paul Webb , Christoph Hellwig , Keith Busch Subject: Re: [bug-report] 5-9% FIO randomwrite ext4 perf regression on 6.12.y kernel Message-ID: <20241121045714.GA20680@lst.de> References: <392209D9-5AC6-4FDE-8D84-FB8A82AD9AEF@oracle.com> <0cfbfcf6-08f5-4d1b-82c4-729db9198896@nvidia.com> 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: User-Agent: Mutt/1.5.17 (2007-11-01) On Wed, Nov 20, 2024 at 06:20:12PM -0700, Jens Axboe wrote: > There's no way that commit is involved, the test as quoted doesn't even > touch write zeroes. Hence if there really is a regression here, then > it's either not easily bisectable, some error was injected while > bisecting, or the test itself is bimodal. ext4 actually has some weird lazy init code using write zeroes. So if the test actually wasn't a steady state one but only run for a short time after init, and the mentioned commit dropped the intel hack for deallocate as write zeroes it might actually make a difference. To check for that do a : /sys/block/nvmeXn1/queue/write_zeroes_max_bytes with and without that commit.