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Subject: Re: [PATCH v2] examples/l3fwd: adjust Tx burst size based on Rx burst
To: Stephen Hemminger <stephen@networkplumber.org>, Sivaprasad Tummala
 <sivaprasad.tummala@amd.com>
CC: <david.hunt@intel.com>, <anatoly.burakov@intel.com>, <jerinj@marvell.com>, 
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On 2025/6/9 23:21, Stephen Hemminger wrote:
> On Mon, 9 Jun 2025 09:58:27 +0000
> Sivaprasad Tummala <sivaprasad.tummala@amd.com> wrote:
> 
>> Previously, the TX burst size was fixed at 256, leading to performance
>> degradation in certain scenarios.
>>
>> This patch introduces logic to set the TX burst size to match the
>> configured RX burst size (--burst option, default 32, max 512)
>> for better efficiency.
>>
>> Fixes: d5c4897ecfb2 ("examples/l3fwd: add option to set Rx burst size")
>> Cc: haijie1@huawei.com
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Sivaprasad Tummala <sivaprasad.tummala@amd.com>
>> Tested-by: Venkat Kumar Ande <VenkatKumar.Ande@amd.com>
>> Tested-by: Dengdui Huang <huangdengdui@huawei.com>
> 
> What driver? Why not fix the driver.
> If RX burst is small, there should be no way to get TX burst larger
> than that to happen.

If the Tx burst is too large, a number of mbufs will be temporarily stored in l3fwd's mbuf_table in a short period of time.
This leads to a decrease in the hit rate of the mempool cache, resulting in a drop in performance.