Date: Sat, 21 Apr 2012 23:49:49 -0700 From: Jack Vogel <jfvogel@gmail.com> To: Vijay Singh <vijju.singh@gmail.com> 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 ?? Message-ID: <CAFOYbck5XeKYRTHbrOZr=oQR=pzqBb8ioCm-VWiXBy3TxOZfBA@mail.gmail.com> In-Reply-To: <CALCNsJTYGTV_uO5dhu_XGmPAPFp5sZ1UwBv1t2Xcd=tXcgfA8w@mail.gmail.com> References: <1334705064.4486.23.camel@powernoodle-l7.corp.yahoo.com> <1334767746.3466.6.camel@powernoodle-l7.corp.yahoo.com> <1334792417.19343.11.camel@powernoodle-l7.corp.yahoo.com> <201204190822.31010.jhb@freebsd.org> <CAFOYbcnXGM7ZMht5_LGp%2B7JJ9s4-8_NTdzx-U4pPLDcspUApMA@mail.gmail.com> <CALCNsJTYGTV_uO5dhu_XGmPAPFp5sZ1UwBv1t2Xcd=tXcgfA8w@mail.gmail.com>
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Yes, I'm not sure what the actual hard limit is, will check that on Monday, but you can go over 4K, it was just a limit I created. Jack On Sat, Apr 21, 2012 at 10:51 PM, Vijay Singh <vijju.singh@gmail.com> wrote: > >> 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 >
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