From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <olivier.matz@6wind.com> Received: from mail-wr0-f170.google.com (mail-wr0-f170.google.com [209.85.128.170]) by dpdk.org (Postfix) with ESMTP id 21B0E1396 for <dev@dpdk.org>; Wed, 15 Mar 2017 11:29:11 +0100 (CET) Received: by mail-wr0-f170.google.com with SMTP id u108so7820990wrb.3 for <dev@dpdk.org>; Wed, 15 Mar 2017 03:29:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=6wind-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=GZryCnnfyE/CsbLALr5fVY2T6XMylrJvPzHXQRb4msw=; b=xVJ1jfIj9xcznmYKUjFW+uS9LUhU7UIWxz+/dmdQjt7uPCSr6qhBs1yBJtpLSMHKR9 ojgub/ruvqrVdMI4seo7HkFXwOe1yiFwOs6lWnkVhR9bxakj9/TQwQxNVUxs1KYK+NZu MFGb5j0F17wX03Or31zfFDy6Gn2iMzgltlfQyaHWzB69tIx1/cBw1SXbae5zWa/2GFMb AQrIHPwxGH+TB0DyDXmM2USGa9dH+cO9/w70I6MAVEy1VTp4g29i7ba2LIKVDnEQ0OB3 M6doBeRbitujebkAmAyi0txaIhn4Jb8WBcBBgUvdIbNFe8rzup9+g090qIdPNA0YJIjt QWIg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=GZryCnnfyE/CsbLALr5fVY2T6XMylrJvPzHXQRb4msw=; b=r9d15Tp6QQBoLc9/GZ2bm7lXolgyJFGZGGRAGcSoPBBKhMZ90qYBpcySydXipORb1J VcbeVJoeipMvLwqtH7PaBO8D51y5HkFCtrq85fOU76K29O0SpH5Lo4NtFWzJR9VxT9PW 0xQwxaSh+agPwDhtU7TXN8Rnw1FOXd7DTvPsyMtmsr7lRoRejFI5/zHDGAXeqVbmgs1E XuPLflVEJXazjRMMSNfSmYwyP25pJJ9zQfbzUa90oSlWjz4g2MlpNhaPzRXtiGoq9p1Z RUQxyqS5xsQ8MPJTIqLflpxB8NRMQ6tx8HCYkdVIg27/dbqE6jL5IYSoc121KQRfO+Uq BNSw== X-Gm-Message-State: AFeK/H3poVlv3eU27rFKVOySvvilRUlTAkgaXOPTKtBJcpHuflrv1AlklfzwXN6w+cNoSjcJ X-Received: by 10.223.160.231 with SMTP id n36mr2614411wrn.167.1489573750793; Wed, 15 Mar 2017 03:29:10 -0700 (PDT) Received: from platinum (2a01cb0c03c651000226b0fffeed02fc.ipv6.abo.wanadoo.fr. [2a01:cb0c:3c6:5100:226:b0ff:feed:2fc]) by smtp.gmail.com with ESMTPSA id s17sm1813694wrc.25.2017.03.15.03.29.10 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 15 Mar 2017 03:29:10 -0700 (PDT) Date: Wed, 15 Mar 2017 11:29:08 +0100 From: Olivier Matz <olivier.matz@6wind.com> To: Billy McFall <bmcfall@redhat.com> Cc: thomas.monjalon@6wind.com, wenzhuo.lu@intel.com, dev@dpdk.org Message-ID: <20170315112908.15b4c811@platinum> In-Reply-To: <20170309205119.28170-2-bmcfall@redhat.com> References: <20170127183800.27466-1-bmcfall@redhat.com> <20170309205119.28170-1-bmcfall@redhat.com> <20170309205119.28170-2-bmcfall@redhat.com> X-Mailer: Claws Mail 3.14.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] [PATCH v6 1/3] ethdev: new API to free consumed buffers in Tx ring X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions <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: Wed, 15 Mar 2017 10:29:11 -0000 Hi Billy, On Thu, 9 Mar 2017 15:51:17 -0500, Billy McFall <bmcfall@redhat.com> wrote: > Add a new API to force free consumed buffers on Tx ring. API will return > the number of packets freed (0-n) or error code if feature not supported > (-ENOTSUP) or input invalid (-ENODEV). > > Please double check my python coding in conf.py and make sure I > implemented 'feature_str_len' properly. > > Signed-off-by: Billy McFall <bmcfall@redhat.com> [...] > diff --git a/doc/guides/prog_guide/mempool_lib.rst b/doc/guides/prog_guide/mempool_lib.rst > index ffdc109..a117881 100644 > --- a/doc/guides/prog_guide/mempool_lib.rst > +++ b/doc/guides/prog_guide/mempool_lib.rst > @@ -132,6 +132,32 @@ These user-owned caches can be explicitly passed to ``rte_mempool_generic_put()` > The ``rte_mempool_default_cache()`` call returns the default internal cache if any. > In contrast to the default caches, user-owned caches can be used by non-EAL threads too. > > +In addition to a core's local cache, many of the drivers don't release the mbuf back to the mempool, or local cache, > +immediately after the packet has been transmitted. > +Instead, they leave the mbuf in their Tx ring and either perform a bulk release when the ``tx_rs_thresh`` has been > +crossed or free the mbuf when a slot in the Tx ring is needed. > + > +An application can request the driver to release used mbufs with the ``rte_eth_tx_done_cleanup()`` API. > +This API requests the driver to release mbufs that are no longer in use, independent of whether or not the > +``tx_rs_thresh`` has been crossed. > +There are two scenarios when an application may want the mbuf released immediately: > + > +* When a given packet needs to be sent to multiple destination interfaces (either for Layer 2 flooding or Layer 3 > + multi-cast). > + One option is to make a copy of the packet or a copy of the header portion that needs to be manipulated. > + A second option is to transmit the packet and then poll the ``rte_eth_tx_done_cleanup()`` API until the reference > + count on the packet is decremented. > + Then the same packet can be transmitted to the next destination interface. > + > +* If an application is designed to make multiple runs, like a packet generator, and one run has completed. > + The application may want to reset to a clean state. > + In this case, it may want to call the ``rte_eth_tx_done_cleanup()`` API to request each destination interface it has > + been using to release all of its used mbufs. > + > +To determine if a driver supports this API, check for the *Free Tx mbuf on demand* feature in the *Network Interface > +Controller Drivers* document. I'm not sure the mempool documentation is the proper place to document this API. I'll suggest to move it in ethdev documentation (poll_mode_drv.rst). You can keep a small paragraph in mempool lib, but keep in mind that mempool is not necessarily a pool of mbuf (it can be any kind of object). Thanks, Olivier