From owner-freebsd-net@FreeBSD.ORG Mon Jan 21 04:02:30 2013 Return-Path: Delivered-To: net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id 44D88634 for ; Mon, 21 Jan 2013 04:02:30 +0000 (UTC) (envelope-from vijju.singh@gmail.com) Received: from mail-ee0-f52.google.com (mail-ee0-f52.google.com [74.125.83.52]) by mx1.freebsd.org (Postfix) with ESMTP id CF5B6809 for ; Mon, 21 Jan 2013 04:02:29 +0000 (UTC) Received: by mail-ee0-f52.google.com with SMTP id b15so2600627eek.39 for ; Sun, 20 Jan 2013 20:02:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:date:message-id:subject:from:to :content-type; bh=JUtjVDocRouGdWt4Ny8PHh7OuaawCZlCkU5DEnRzsII=; b=qqZkAOs767iCA6qpWSSDwan+5hPfy+IUz/r+V3HQQhkK29RzRZuTvw5msoFbeOSrLu qV5DM+hCK+hiqDuQNTPgsGENJvMvdph4C3uFBICJNmcmWnbQ1BoW1ldb9SVNPiHCnwfd rFQXHUzgbosqJwvK+iuJiM6InNAkFI9Ibz391GGmSAxKPyUFnsiIZFN6RLtms+fPRBna mpUgoOExnYnV35iTglm6BX8tKqdZ2Cxt0AVLFEOREjo2Xhn0VKkb5xHbr5h525XAINkR 6cPARTJ2iJgYShmvXpt16FuftGBHVWOCMiBdMo3FIQHLAQ7nc7ovYQ5E+ScJt1Gx0Ygr eDgw== MIME-Version: 1.0 X-Received: by 10.14.177.1 with SMTP id c1mr55711470eem.8.1358740943238; Sun, 20 Jan 2013 20:02:23 -0800 (PST) Received: by 10.223.101.77 with HTTP; Sun, 20 Jan 2013 20:02:23 -0800 (PST) Date: Sun, 20 Jan 2013 20:02:23 -0800 Message-ID: Subject: Avoiding duplicate ACKs in TCP From: Vijay Singh To: net@freebsd.org Content-Type: text/plain; charset=ISO-8859-1 X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 21 Jan 2013 04:02:30 -0000 All. I am working on an in-kernel application using socket upcalls. I see a lot of TCP DUP ACKs due the call to tcp_usr_rvcd(). However if I avoid this in the upcall using the MSG_SOCALLBCK flag to soreceive() the throughput of the test goes down due to missing window updates. I am wondering if there is a way to avoid this, perhaps by sending the window update based on data read by the application. -vijay