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From: David Marchand <david.marchand@6wind.com>
To: "Zhang, Helin" <helin.zhang@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] i40e: Steps and required configurations of how to achieve the best performance!
Date: Wed, 17 Sep 2014 16:03:05 +0200	[thread overview]
Message-ID: <CALwxeUs-x=7Zs+08vRssD-kd4R3Y1FexF98pcGeFD9kAxF3KqQ@mail.gmail.com> (raw)
In-Reply-To: <F35DEAC7BCE34641BA9FAC6BCA4A12E70A793694@SHSMSX104.ccr.corp.intel.com>

On Wed, Sep 17, 2014 at 10:50 AM, Zhang, Helin <helin.zhang@intel.com>

>  For the ‘extended tag’, it was defined in PCIe spec, but actually not
> all BIOS implements it. Enabling it in BIOS or at runtime are two choices
> of doing the same thing. I don’t think it can be configured per PCI device
> in BIOS, so we don’t need to do that per PCI device in DPDK. Right?
> Actually we don’t want to touch PCIe settings in DPDK code, that’s why we
> want to let BIOS config as it is by default. If no better choice, we can do
> it in DPDK by changing configurations.

- Ok, then if we can make a runtime decision (at dpdk level), there is no
need for bios configuration and there is no need for a build option.
Why don't we get rid of this option ?

As far as the per-device runtime configuration is concerned, I want to make
sure this pci configuration will not break other "igb_uio" pci devices.
If Intel can tell for sure this won't break other devices, then fine, we
can go and enable this for all "igb_uio" pci devices.

- By the way, there is also the CONFIG_MAX_READ_REQUEST_SIZE option that
seems to be disabled (or at least its value 0 seems to tell so).
What is its purpose ?

> For ‘CONFIG_RTE_LIBRTE_I40E_16BYTE_RX_DESC=n’ by default, we want to
> support 32 bytes rx descriptors by default. Two reasons:
> One is 32 bytes rx descriptors can provide more powerful features, and
> more offload features.
> The other is Linux PF host use 32 bytes rx descriptor by default which
> might not able to be changed, to support Linux PF host, it would be better
> to use 32 bytes rx descriptors in DPDK VF by default.

Ok, good to know.


David Marchand

  reply	other threads:[~2014-09-17 13:57 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-17  4:18 Zhang, Helin
2014-09-17  8:33 ` David Marchand
2014-09-17  8:50   ` Zhang, Helin
2014-09-17 14:03     ` David Marchand [this message]
2014-09-18  2:39       ` Zhang, Helin
2014-09-18  8:57         ` David Marchand
2014-09-19  3:43           ` Zhang, Helin
2014-10-15  9:41             ` Thomas Monjalon
2014-10-16  0:43               ` Zhang, Helin
2015-02-09 12:12                 ` David Marchand
2015-02-10  0:27                   ` Zhang, Helin

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