From owner-freebsd-stable@FreeBSD.ORG Sun Jul 7 09:24:55 2013 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 23CB2FF6 for ; Sun, 7 Jul 2013 09:24:55 +0000 (UTC) (envelope-from kaushalgoa@gmail.com) Received: from mail-ea0-x22e.google.com (mail-ea0-x22e.google.com [IPv6:2a00:1450:4013:c01::22e]) by mx1.freebsd.org (Postfix) with ESMTP id B338B1C38 for ; Sun, 7 Jul 2013 09:24:54 +0000 (UTC) Received: by mail-ea0-f174.google.com with SMTP id o10so2282210eaj.33 for ; Sun, 07 Jul 2013 02:24:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :content-type; bh=ZJc8ucmJArd8HCA4mKtGT6miH1H5M0hKCy+tfaP1n5A=; b=RMcwK8l4vNKoXjCVG4cDv202P45RBwTuHqttshre7l/39d5JJZIpjbte2APG3RcBI1 kEcTbqYihxSx8bhSTr5EwLI86covUHWJ6rGPvBDSDLQKjiQBZJg7DHwOWtDavOHnenjK wr3M/IbHw3N2+KRvdHg5kek0/sHVgZNE2PDO33iJq9hDK0TjXqKQtByLdwVRFFbInDtS ImoHCO+tl59oFBHAV7AqRXBKEkl+c1bwRvtZmE6CFXrOwlZ0sRMlW527QrakAQhocsom 4WDqoKX+V3UFSNBVhySryVbzdt9BvpxJkmMivVbfKCYlniT7D+vrRPyheHBEK+i1kIyD hWUg== X-Received: by 10.14.2.73 with SMTP id 49mr19666786eee.118.1373189093622; Sun, 07 Jul 2013 02:24:53 -0700 (PDT) MIME-Version: 1.0 Received: by 10.14.138.141 with HTTP; Sun, 7 Jul 2013 02:24:33 -0700 (PDT) In-Reply-To: References: From: Kaushal Bhandankar Date: Sun, 7 Jul 2013 14:54:33 +0530 Message-ID: Subject: Fwd: ixgbe Jumbo race condition leading to Deadlock To: freebsd-stable@freebsd.org Content-Type: text/plain; charset=ISO-8859-1 X-Content-Filtered-By: Mailman/MimeDel 2.1.14 X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 07 Jul 2013 09:24:55 -0000 In 82599, for a Jumbo packet of 9.5 K ( which consumes 5 descriptors of 2048 bytes each ), when does the Descriptor write back happen ? Does it happen per Descriptor or once per aggregated Descriptors ? Is it possible that all descriptors except last one to be written back and when you read RDH register, I get the last pending descriptor waiting inside 82599. We are using srrctl |= IXGBE_SRRCTL_DESCTYPE_ADV_ONEBUF; In my setup, I am seeing that, I don't see EOP set even when I read 5 descriptors. Checking DD will return me an incomplete packet. What should I do in such a case ? References from Data sheet: -> Checking through DD bits eliminates a potential race condition: all descriptor data is posted internally prior to incrementing the head register and a read of the head register could potentially pass the descriptor waiting inside the 82599. Regards, Kaushal