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 889FC223DF9; Fri, 26 Sep 2025 15:55:06 +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=1758902106; cv=none; b=N6VqY4zfqa6s5zUAt8sEUGSzOwSs5Ly9ZaEXn6IJb77eClyQYhtHfdkAA++/wGHTqz7/2wT62EqelfS5Qs2QCMXxV3acxjmEscInLPB3UGt2rkqHEK8ESGnjW8g4wUzVHFxFF9I9sAYwQblaoBJ74PvIeTOtREqHl0MTwc8qN38= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758902106; c=relaxed/simple; bh=QY04EA7f9rFZc1ry5RbDdee1eH1ZtF6RNbYZ864Iejg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=eb7O4RMQTPpNRm1AKmnzvm1eS3WNeiWy8OJxIHMqOxsHOIZ9g4gWKHM2rtF3MRcOqpSVMF2HkZwcJR5RJMGWwM3Z2rjy1Pt0++U9JOQzLBgvT5A5zd0q6cWxMU1Dp/J9HeSl956zvc5bptKfqJvP42j+Jk9AKjquB1OWdtYnqdo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VW6u7eIx; 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="VW6u7eIx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 66F4BC4CEF4; Fri, 26 Sep 2025 15:55:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758902106; bh=QY04EA7f9rFZc1ry5RbDdee1eH1ZtF6RNbYZ864Iejg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VW6u7eIxwWH1cr753V5J2LxOOHjIM2+OJigjWqXy14dsgdSVDAbzEcPIWJG0VyCLK IiccvlAsT6yUeZltR+hEk/dtzTgYiN8iGJTIaVOiWciMEjQIh8uwa5Sh9LyZzxGHdf 6e+BTEIFUWgoEllJmVhO84ZDyvqyCJ6GclSVEfh/uoWb9G74cMnPpPgmp3myebEVZT DH2NM9Sku3+IlbR22ooNMdKu92dc99ruSbBvc6LFrXx6D8l3z8ZLXsoFZytC/jToL5 HZntiHHn+c/Q5BCRPQfrm9x5FaiE+yy/dZTmjzhS3CQcPXb1K/+j+ptQywWfdiudnf m8wiQxKpt7BPg== Date: Fri, 26 Sep 2025 16:55:01 +0100 From: Simon Horman To: Bobby Eshleman Cc: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Kuniyuki Iwashima , Willem de Bruijn , Neal Cardwell , David Ahern , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Stanislav Fomichev , Mina Almasry , Bobby Eshleman Subject: Re: [PATCH net-next v3 0/2] net: devmem: improve cpu cost of RX token management Message-ID: References: <20250926-scratch-bobbyeshleman-devmem-tcp-token-upstream-v3-0-084b46bda88f@meta.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: <20250926-scratch-bobbyeshleman-devmem-tcp-token-upstream-v3-0-084b46bda88f@meta.com> On Fri, Sep 26, 2025 at 08:02:52AM -0700, Bobby Eshleman wrote: > This series improves the CPU cost of RX token management by replacing > the xarray allocator with an niov array and a uref field in niov. > > Improvement is ~5% per RX user thread. > > Two other approaches were tested, but with no improvement. Namely, 1) > using a hashmap for tokens and 2) keeping an xarray of atomic counters > but using RCU so that the hotpath could be mostly lockless. Neither of > these approaches proved better than the simple array in terms of CPU. > > Running with a NCCL workload is still TODO, but I will follow up on this > thread with those results when done. > > Signed-off-by: Bobby Eshleman Hi Bobby, Unfortunately this patchset doesn't apply cleanly to net-next. So you'll need to rebase and repost at some point. -- pw-bot: changes-requested