Re: [dpdk-dev] [PATCH v2 0/3] Support setting TX rate for queue and VF

["Ouyang, Changchun" <changchun.ouyang@intel.com>]

Hi, Neil

" but you're implementaiton requires that it be re-implemented for each PMD "

[Changchun]: Different PMD(corresponding diff NIC) has different register to set.
It makes sense to me has different implementation to support limit tx rate.
 
" Why not just export max tx rates from the PMD and write a generic queuing libarary to do rate limitation for any PMD?"

[Changchun]: Just export max tx rate is not enough for customer.
I think if we can leverage HW feature to do it, why need a more complicated lib to do so? 

Thanks
Changchun

-----Original Message-----
From: Neil Horman [mailto:nhorman@tuxdriver.com] 
Sent: Tuesday, May 27, 2014 6:53 AM
To: Ouyang, Changchun
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH v2 0/3] Support setting TX rate for queue and VF

On Mon, May 26, 2014 at 03:45:28PM +0800, Ouyang Changchun wrote:
> This patch v2 fixes some errors and warnings reported by checkpatch.pl.
>  
> This patch series also contain the 3 items:
> 1. Add API to support setting TX rate for a queue or a VF.
> 2. Implement the functionality of setting TX rate for queue or VF in IXGBE PMD.
> 3. Add commands in testpmd to test the functionality of setting TX rate for queue or VF.
> 
> Ouyang Changchun (3):
>   Add API to support set TX rate for a queue and VF.
>   Implement the functionality of setting TX rate for queue or VF in
>     IXGBE PMD.
>   Add commands in testpmd to test the functionality of setting TX rate
>     for queue or VF.
> 
>  app/test-pmd/cmdline.c              | 159 +++++++++++++++++++++++++++++++++++-
>  app/test-pmd/config.c               |  47 +++++++++++
>  app/test-pmd/testpmd.h              |   3 +
>  lib/librte_ether/rte_ethdev.c       |  71 ++++++++++++++++
>  lib/librte_ether/rte_ethdev.h       |  51 ++++++++++++
>  lib/librte_pmd_ixgbe/ixgbe_ethdev.c | 122 +++++++++++++++++++++++++++  
> lib/librte_pmd_ixgbe/ixgbe_ethdev.h |  13 ++-
>  7 files changed, 462 insertions(+), 4 deletions(-)
> 
This seems a bit backwards.  queue rate limiting is rather a generic function, that doesn't really need to know any details about the hardware, save for its maximum tx rate, but you're implementaiton requires that it be re-implemented for each PMD.  Why not just export max tx rates from the PMD and write a generic queuing libarary to do rate limitation for any PMD?

Neil

> --
> 1.9.0
> 
>