From owner-freebsd-stable@FreeBSD.ORG Tue Sep 25 10:41:51 2007 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 38E0C16A417 for ; Tue, 25 Sep 2007 10:41:51 +0000 (UTC) (envelope-from matrix@itlegion.ru) Received: from corpmail.itlegion.ru (corpmail.itlegion.ru [84.21.226.211]) by mx1.freebsd.org (Postfix) with SMTP id 463D013C455 for ; Tue, 25 Sep 2007 10:41:50 +0000 (UTC) (envelope-from matrix@itlegion.ru) Received: (qmail 98165 invoked from network); 25 Sep 2007 14:41:47 +0400 Received: from unknown (HELO Artem) (192.168.0.12) by 84.21.226.211 with SMTP; 25 Sep 2007 14:41:47 +0400 X-AntiVirus: Checked by Dr.Web [version: 4.33, engine: 4.33.5.10110, virus records: 254448, updated: 25.09.2007] Message-ID: <00f901c7ff60$aa84ed50$0c00a8c0@Artem> From: "Artem Kuchin" To: "Nikos Vassiliadis" References: <01ae01c7fd3e$e6ff28f0$0c00a8c0@Artem> <200709251048.20808.nvass@teledomenet.gr> <00b801c7ff54$6796f2b0$0c00a8c0@Artem> <200709251249.11287.nvass@teledomenet.gr> Date: Tue, 25 Sep 2007 14:41:43 +0400 Organization: IT Legion MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="koi8-r"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 Cc: freebsd-stable@freebsd.org Subject: Re: device polling and weird timer interrupt count from vmstat X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 25 Sep 2007 10:41:51 -0000 Nikos Vassiliadis wrote: > On Tuesday 25 September 2007 12:13, Artem Kuchin wrote: >> I have dual CPU with HT. If i turn on HT (and it does help in my >> case) it shoud 2000 int x4 = 8000 ints per second. SO, i have saved >> 200 int/second from NIC and got myself 8000 ints/second from timer. > > This kind of load(200intrs/s) earns nothing from polling. > >> Did i >> really win anything? I wish there were some good explanation on this. > > It would make a difference for let's say 8000 - 10000 interrupts/sec. > You should read polling(4). It explains a lot:) Yes, i have read the man for polling. However, it does not contain info on when it worth enabling. From this point of view it seems like if i have 8CPU server an a NIC with 8000 ints/sec when i enable polling with HZ=1000 i get about 30 ints/sec from NIC about 16000 ints from NIC So, we were at 8000 ints a second and now we are at 16000 ints/second. Is it worth in this case? It seems like enabling polling on really multi cpu computers never worth it. I think there is a mistake in my logic here. It just canot be like this. any thoughts? -- Regards, Artem