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Date: Sat, 21 Apr 2012 22:51:37 -0700
Message-ID: <CALCNsJTYGTV_uO5dhu_XGmPAPFp5sZ1UwBv1t2Xcd=tXcgfA8w@mail.gmail.com>
From: Vijay Singh <vijju.singh@gmail.com>
To: Jack Vogel <jfvogel@gmail.com>
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Cc: freebsd-net@freebsd.org, Luigi Rizzo <rizzo@iet.unipi.it>,
	Sean Bruno <seanbru@yahoo-inc.com>, John Baldwin <jhb@freebsd.org>
Subject: Re: igb(4) Raising IGB_MAX_TXD ??
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>> FWIW, at my current employer we run with both rxd and txd cranked up to 32k
>> (we had to patch the driver as you suggested) and have not had any problems
>> doing that for a couple of years now.

John et al, is this limit specific to igb, or is it applicable to the
ixgbe as well. From the 8.x driver code I see:

100/*
101 * TxDescriptors Valid Range: 64-4096 Default Value: 256 This value is the
102 * number of transmit descriptors allocated by the driver. Increasing this
103 * value allows the driver to queue more transmits. Each descriptor is 16
104 * bytes. Performance tests have show the 2K value to be optimal for top
105 * performance.
106 */
107#define DEFAULT_TXD	1024
108#define PERFORM_TXD	2048
109#define MAX_TXD		4096
110#define MIN_TXD		64

Can the igxbe be extended beyond 4k transmit descriptors well?

-vijay