From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Fainelli Subject: Re: [PATCH net-next 0/2] net: broadcom: Adaptive interrupt coalescing Date: Mon, 26 Mar 2018 15:04:13 -0700 Message-ID: <4625ee80-9588-e39c-5add-3c57432c1141@gmail.com> References: <20180323011933.29748-1-f.fainelli@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: davem@davemloft.net, jaedon.shin@gmail.com, pgynther@google.com, opendmb@gmail.com, michal.chan@broadcom.com, gospo@broadcom.com, saeedm@mellanox.com To: Tal Gilboa , netdev@vger.kernel.org Return-path: Received: from mail-qk0-f195.google.com ([209.85.220.195]:36861 "EHLO mail-qk0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751805AbeCZWEY (ORCPT ); Mon, 26 Mar 2018 18:04:24 -0400 Received: by mail-qk0-f195.google.com with SMTP id o205so10242476qke.3 for ; Mon, 26 Mar 2018 15:04:24 -0700 (PDT) In-Reply-To: Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: On 03/26/2018 02:16 PM, Tal Gilboa wrote: > On 3/23/2018 4:19 AM, Florian Fainelli wrote: >> Hi all, >> >> This patch series adds adaptive interrupt coalescing for the Gigabit >> Ethernet >> drivers SYSTEMPORT and GENET. >> >> This really helps lower the interrupt count and system load, as >> measured by >> vmstat for a Gigabit TCP RX session: > > I don't see an improvement in system load, the opposite - 42% vs. 100% > for SYSTEMPORT and 85% vs. 100% for GENET. Both with the same bandwidth. Looks like I did not extract the correct data the load could spike in both cases (with and without net_dim) up to 100, but averaged over the transmission I see the following: GENET without: 1 0 0 1169568 0 25556 0 0 0 0 130079 62795 2 86 13 0 0 GENET with: 1 0 0 1169536 0 25556 0 0 0 0 10566 10869 1 21 78 0 0 > Am I missing something? Talking about bandwidth, I would expect 941Mb/s > (assuming this is TCP over IPv4). Do you know why the reduced interrupt > rate doesn't improve bandwidth? I am assuming that this comes down to a latency, still capturing some pcap files to analyze the TCP session with wireshark and see if that is indeed what is going on. The test machine is actually not that great > Also, any effect on the client side (you > mentioned enabling TX moderation for SYSTEMPORT)? Yes, on SYSTEMPORT, being the TCP IPv4 client, I have the following: SYSTEMPORT without: 2 0 0 191428 0 25748 0 0 0 0 86254 264 0 41 59 0 0 SYSTEMPORT with: 3 0 0 190176 0 25748 0 0 0 0 45485 31332 0 100 0 0 0 I don't get top to agree with these load results though but it looks like we just have the CPU spinning more, does not look like a win. Thanks a lot for taking a look at this Tal! -- Florian