From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <alex@weka.io>
Received: from mail-oa0-f41.google.com (mail-oa0-f41.google.com
 [209.85.219.41]) by dpdk.org (Postfix) with ESMTP id DB2E336D
 for <dev@dpdk.org>; Mon, 30 Jun 2014 12:00:32 +0200 (CEST)
Received: by mail-oa0-f41.google.com with SMTP id l6so8681639oag.0
 for <dev@dpdk.org>; Mon, 30 Jun 2014 03:00:52 -0700 (PDT)
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
 d=1e100.net; s=20130820;
 h=x-gm-message-state:mime-version:date:message-id:subject:from:to
 :content-type;
 bh=B79z4W7FX8QiU99GoH3tD27LsgD25GZr32/KqT5qpMQ=;
 b=Yg1HDfqXk0JU9sMnJooOSg5IUIA6FxBg6u/YZ7O5Aih86JM8l9QulBDZwb7Wt0MDG6
 cT2jSHXouPMaTAELNOkTgt/IEx/3seHGKsLyYSj+lcI3jNigtTDzpuatxsFRv6K0y7Yb
 1qWiH2Jy5/No4UFS2/ee+u2xu2hZGnMCBA9Grvi+fBoyFOeWbdXsJG7OW4F5Jxf0kEGb
 xT0HovzBfhG5iAVeEG6oz6XXGXV5vV973qHSTX+0CuLxAHvOoDJicZRRAaLpDDKlMQ9w
 K0LiczoP0QJtjzX8FZl1tgBMk+YlkzxlCT67aAsV/kmvCVMp4686qV2UWQBwZe8wGCBg
 KgNA==
X-Gm-Message-State: ALoCoQke14GZddBx93RCoAJPcnEnroKep5cvNTatMcS8Jk8NDQm9cs+GH6Vkmt6hJQqAF+Mtolxh
MIME-Version: 1.0
X-Received: by 10.60.129.161 with SMTP id nx1mr40806194oeb.28.1404122452059;
 Mon, 30 Jun 2014 03:00:52 -0700 (PDT)
Received: by 10.202.202.137 with HTTP; Mon, 30 Jun 2014 03:00:52 -0700 (PDT)
Date: Mon, 30 Jun 2014 13:00:52 +0300
Message-ID: <CAKfHP0Vi2OAaiiQpKNYStwAFrApLHQDTwVADTm4wmEE30kbKfA@mail.gmail.com>
From: Alex Markuze <alex@weka.io>
To: dev@dpdk.org
Content-Type: text/plain; charset=UTF-8
X-Content-Filtered-By: Mailman/MimeDel 2.1.15
Subject: [dpdk-dev] Memory Pinning.
X-BeenThere: dev@dpdk.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: patches and discussions about DPDK <dev.dpdk.org>
List-Unsubscribe: <http://dpdk.org/ml/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://dpdk.org/ml/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <http://dpdk.org/ml/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
X-List-Received-Date: Mon, 30 Jun 2014 10:00:33 -0000

Hi, Guys.
I have several newbie questions about the DPDK design I was hoping some one
could answer.

Both in the RX and TX flow, the Buffer Memory must be pinned and not
swappable.
In RDMA, memory is explicitly registered and made pinned (to the limit
defined @ /etc/security/limits.conf) .With regular sockets/kernel driver
the NIC DMA's the buffer from/to the kernel which are by definition un
swappable.

So I'm guessing that at least the TX/RX buffers are mapped to kernel space.

My questions are 1. How are the buffers made unswappable ? Are they shared
with the kernel 2. When and Which buffers are mapped/unmapped to the kernel
space. 3. When are the buffers DMA mapped and by whom?

And another "bonus" Question. On TX flow I didn't find a way to receive a
send completion.
So how Can I know when its safe to modify the sent buffers (besides of
waiting for the ring buffer to complete a full circle)?


Thanks.
Alex.