Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755371AbZLCQ6Z (ORCPT ); Thu, 3 Dec 2009 11:58:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755012AbZLCQ6Z (ORCPT ); Thu, 3 Dec 2009 11:58:25 -0500 Received: from zrtps0kp.nortel.com ([47.140.192.56]:46441 "EHLO zrtps0kp.nortel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754977AbZLCQ6Y (ORCPT ); Thu, 3 Dec 2009 11:58:24 -0500 Message-ID: <4B17ED8D.7050409@nortel.com> Date: Thu, 03 Dec 2009 10:55:41 -0600 From: "Chris Friesen" User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.4pre) Gecko/20090922 Fedora/3.0-2.7.b4.fc11 Thunderbird/3.0b4 MIME-Version: 1.0 To: Eric Dumazet CC: netdev@vger.kernel.org, Linux kernel Subject: Re: seeing strange values for tcp sk_rmem_alloc References: <4B15416A.2060202@nortel.com> <4B154B29.1030807@cosmosbay.com> <4B155252.1040604@nortel.com> <4B1557CC.4060503@gmail.com> In-Reply-To: <4B1557CC.4060503@gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 03 Dec 2009 16:58:16.0847 (UTC) FILETIME=[CF0241F0:01CA7439] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1977 Lines: 114 On 12/01/2009 11:52 AM, Eric Dumazet wrote: > But be careful of sender tcp stack : It might be delayed a bit, > because it waits for receiver to open its window (slow start) > > You probably need something like > > while (1) { > send(fd1, buffer, 2Kbytes); > sleep(2); // let tcp stack flush its write buffers > display_sk_rmem_alloc(fd2); > } Ah, that makes a difference. But the results (see below) still look odd. For this test, /proc/sys/net/core/rmem_default is 118784. For some reason sk_rmem_alloc gets bumped by 16KB when I only send 2KB of data, and it drops back down again every 6 packets. Chris used: 16848 used: 33696 used: 50544 used: 67392 used: 84240 used: 101088 used: 30736 used: 47584 used: 64432 used: 81280 used: 98128 used: 114976 used: 44624 used: 61472 used: 78320 used: 95168 used: 112016 used: 128864 used: 58512 used: 75360 used: 92208 used: 109056 used: 125904 used: 142752 used: 72400 used: 89248 used: 106096 used: 122944 used: 139792 used: 156640 used: 86288 used: 103136 used: 119984 used: 136832 used: 153680 used: 170528 used: 100176 used: 117024 used: 133872 used: 150720 used: 167568 used: 184416 used: 114064 used: 130912 used: 147760 used: 164608 used: 181456 used: 198304 used: 127952 used: 144800 used: 161648 used: 178496 used: 195344 used: 212192 used: 141840 used: 158688 used: 175536 used: 192384 used: 209232 used: 226080 used: 155728 used: 172576 used: 189424 used: 206272 used: 223120 used: 239968 used: 169616 used: 186464 used: 203312 used: 220160 used: 237008 used: 253856 used: 183504 used: 200352 used: 217200 used: 234048 used: 250896 used: 267744 used: 197392 used: 214240 used: 231088 used: 247936 used: 264784 used: 281632 used: 211280 used: 228128 used: 244976 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/