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 7DB3215AF6 for ; Thu, 23 Jan 2025 08:56:33 +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=1737622593; cv=none; b=X+paJYbDsHUuJ69lO5811TvtXVUEjQWALxNBVhblrKRA0zklgo2xmLa+Okj2VgMJcN+Izb2JepKnEbbO0zGtvITARvY5XhGj6krQDW9cvI9gyBa3/ugT0hhvx+kACtrZzQYhk7EvOjXVqRBLtzXHUSKidzncBjclvL6gh9ck/Fc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737622593; c=relaxed/simple; bh=dgR8kpL+F/8N7nnaWC2oXsO4TBOYFpSAVLK4nCNWiAE=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=ATbOA9dmjRzFcr9l+qDeZhm9wZmvsA1H/f5tWhDMCcBhkyRLpjiD6XVHSjjWgkdl3gT+rYSuUNLwsk2hO8WGRPBHLcfWp6y3HFmPkLZmfasNq7rXMfHHbSO1O0q3KcywJYR6jkqCZFWb1egj5t5vfWyiWPy1kVSXQJhZvFnzxpw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cQHUcpAc; 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="cQHUcpAc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E411CC4CEE0; Thu, 23 Jan 2025 08:56:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1737622592; bh=dgR8kpL+F/8N7nnaWC2oXsO4TBOYFpSAVLK4nCNWiAE=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=cQHUcpAcWzMyK27wZNfgoGvdCR5/83WBP0UPhE6tLuoqlTRaJm+ihwgQjMi+882Aw aH9H8sKZRKm+FrM1bKEI16VCfv3IUwxTK2hqie++9hwXPKcy/8kl2w5TVKqnjuyT9T gT9pKMxUQHLTlMK0gRT49oo4Ce0WQalhnxwx+J7GhPAnKO3u4vNcDd3Slcqx5r98z9 IPgX87y82qxUa2ndSQ3gqvUbQqc3P0OO63xXusFd3mnxXpVUNqE9nyrVuk4YL5l9fF o8px9dTukuCvwdSit/Aarzg4sUF9I26Sv6BYAUzojT6pu9KT1fTu2WB4IJ0QcvdfRo rEMpiy7FdrtUA== From: Andreas Hindborg To: "Niklas Cassel" Cc: "Jan Kara" , , , "Jens Axboe" , "Matthew Wilcox" , "Luis Chamberlain" , "Miguel Ojeda" Subject: Re: [Lsf-pc] [LSF/MM/BPF TOPIC] Rust block layer abstractions and benchmark strategies In-Reply-To: (Niklas Cassel's message of "Wed, 22 Jan 2025 10:52:21 +0100") References: <871pwwctcj.fsf@kernel.org> <87sepcba9s.fsf@kernel.org> User-Agent: mu4e 1.12.7; emacs 29.4 Date: Thu, 23 Jan 2025 09:56:20 +0100 Message-ID: <87y0z1zz63.fsf@kernel.org> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain "Niklas Cassel" writes: > Hello Andreas, > > On Tue, Jan 21, 2025 at 01:51:11PM +0100, Andreas Hindborg wrote: >> Hi Jan, >> >> "Jan Kara" writes: >> >> > Hi! >> > >> > On Tue 21-01-25 12:13:48, Andreas Hindborg via Lsf-pc wrote: >> >> I would like to propose that we have a session on Rust in the block >> >> layer again this year. Specifically I would like to discuss some rather >> >> puzzling results I observe when I benchmark the C and Rust null block >> >> drivers. I did a write up of the challenges I face at [1]. The >> >> observations are not tied to rust, they also manifest in the C driver. >> > >> > The results are indeed somewhat curious. One factor I didn't see addressed >> > in your blog is CPU scheduling. I've seen in the past cases where IO tasks >> > were getting migrated across cores leading to jumps in perfomance. Did you >> > try binding fio jobs to one CPU each? >> >> Yes, I am pinning the io jobs to cores with fio options `cpus_allowed=0-` >> and `--cpus_allowed_policy=split` so I get 1 job per core. >> >> The kernel is configured with PREEMPT_NONE=y. > > "I also cover a problem with the benchmark results that manifested during > testing for v6.12-rc2." > > I assume that all the results on: > https://metaspace.github.io/2024/12/02/problems-in-benchmark-land.html > > are with kernel v6.12-rc2 ? Yes. > > It would be interesting to test an older kernel version, and see if it > is e.g. a scheduler bug. Yes, I did not do that. I should collect some more detailed data for past kernels. > You might also want to test with this series applied (which landed last > minute before v6.13 was tagged): > https://lore.kernel.org/lkml/20250119110410.GAZ4zcKkx5sCjD5XvH@fat_crate.local/T/#u > > > It fixes bugs that were introduced in v6.12-rc1 and v6.7-rc2 respectively. > I'll try that, thanks. Best regards, Andreas Hindborg