netdev - Re: [PATCH 2/2 net-next] bnx2x: Multiple concurrent l2 traffic classes

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Message-Id: <20110714.160255.2277414883184091455.davem@davemloft.net>
Date:	Thu, 14 Jul 2011 16:02:55 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	ariele@...adcom.com
Cc:	netdev@...r.kernel.org, eilong@...adcom.com
Subject: Re: [PATCH 2/2 net-next] bnx2x: Multiple concurrent l2 traffic
 classes

From: "Ariel Elior" <ariele@...adcom.com>
Date: Thu, 14 Jul 2011 21:31:57 +0300

>  Overview:
>  Support mapping of priorities to traffic classes and
>  traffic classes to transmission queues ranges in the net device.
>  The queue ranges are (count, offset) pairs relating to the txq
>  array.
>  This can be done via DCBX negotiation or by kernel.
>  As a result Enhanced Transmission Selection (ETS) and Priority Flow
>  Control (PFC) are supported between L2 network traffic classes.
>  
>  Mapping:
>  This patch uses the netdev_set_num_tc, netdev_set_prio_tc_map and
>  netdev_set_tc_queue functions to map priorities to traffic classes
>  and traffic classes to transmission queue ranges.
>  This mapping is performed by bnx2x_setup_tc function which is
>  connected to the ndo_setup_tc.
>  This function is always called at nic load where by default it
>  maps all priorities to tc 0, and it may also be called by the
>  kernel or by the bnx2x upon DCBX negotiation to modify the mapping.
>  
>  rtnl lock:
>  When the ndo_setup_tc is called at nic load or by kernel the rtnl
>  lock is already taken. However, when DCBX negotiation takes place
>  the lock is not taken. The work is therefore scheduled to be
>  handled by the sp_rtnl task.
>  
>  Fastpath:
>  The fastpath structure of the bnx2x which was previously used
>  to hold the information of one tx queue and one rx queue was
>  redesigned to represent multiple tx queues, one for each traffic
>  class.
>  The transmission queue supplied in the skb by the kernel can no
>  longer be interpreted as a straightforward index into the fastpath
>  structure array, but it must rather be decoded to the appropriate
>  fastpath index and the tc within that fastpath.
>  
>  Slowpath:
>  The bnx2x's queue object was redesigned to accommodate multiple
>  transmission queues. The queue object's state machine was enhanced
>  to allow opening multiple transmission-only connections on top of
>  the regular tx-rx connection.
>  
>  Firmware:
>  This feature relies on the tx-only queue feature introduced in the
>  bnx2x 7.0.23 firmware and the FW likewise must have the bnx2x multi
>  cos support.
> 
>  Signed-off-by: Ariel Elior <ariele@...adcom.com>
>  Signed-off-by: Eilon Greenstein <eilong@...adcom.com>

Applied.
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