[dpdk-dev] [EXT] Re: [PATCH v2 26/37] net/mvpp2: introduce fixup for fifo overrun

Liron Himi lironh at marvell.com
Wed Jan 27 15:08:29 CET 2021



Liron Himi
Staff Software Engineer

 

Park Azorim, Kyriat Arie, Petah Tikva, 49527, Israel
Mobile: +972.52.3329169

-----Original Message-----
From: Ferruh Yigit <ferruh.yigit at intel.com> 
Sent: Wednesday, 27 January 2021 01:50
To: Liron Himi <lironh at marvell.com>; Jerin Jacob Kollanukkaran <jerinj at marvell.com>
Cc: dev at dpdk.org
Subject: [EXT] Re: [dpdk-dev] [PATCH v2 26/37] net/mvpp2: introduce fixup for fifo overrun

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On 1/22/2021 7:19 PM, lironh at marvell.com wrote:
> From: Liron Himi <lironh at marvell.com>
> 
> Currently the HW is configured with only one pool which its buffer 
> size may be larger than the rx-fifo-size.
> In that situation, frame size larger than the fifo-size is gets 
> dropped due to fifo overrun.
> this is cause because the HW works in cut-through mode which waits to 
> have in the fifo at least the amount of bytes as define in the 
> smallest pool's buffer size.
> 
> This patch add a dummy pool which its buffer size is very small 
> (smaller than 64B frame). this tricks the HW and any frame size is 
> gets passed from the FIFO to the PP2.
> 
> Signed-off-by: Liron Himi <lironh at marvell.com>

so this is fixing the FIFO overrun, can you please provide the fixes line?
[L.H.] it is kind of combination of HW fifo size (which defined by kernel driver), given buffer size and incoming pkt size. I don't think I can point to a line in DPDK driver code that this patch is fixing.
it is a kind of WA for a HW issue.

And should this patch backported?
[L.H.] it cannot be backported as it depends on MUSDK api change.



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