mempool cache change

mempool cache change

[Kishore Padmanabha]

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Hi Thomas,



The recent change done as part of BUG ID: 1027, with commit id
https://git.dpdk.org/dpdk/commit/?id=f5e1310f16e0909e7e7f71807123644c63b23cba

Is causing performance drop for the bnxt NIC in 26.07 release.



The smaller, shallower cache increases the miss rate, causing refills to
hit the shared ring more frequently.
In the old code, the cache only touched the shared ring when it climbed
past 768 instead of 512. That extra 256 elements of headroom allowed
significantly more frees to remain local.



Could we make the change in config/rte_config.h for
RTE_MEMPOOL_CACHE_MAX_SIZE to be 768 instead of 512. Since we use
–mbcache=512 as argument for the performance tests.



Thanks,

Kishore

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RE: mempool cache change

[Morten Brørup]

Hi Kishore,

For your testing purposes, please follow the guidance provided to Wisam Jaddo:
https://inbox.dpdk.org/dev/98CBD80474FA8B44BF855DF32C47DC35F65964@smartserver.smartshare.dk/

Thank you for testing!

Venlig hilsen / Kind regards,
-Morten Brørup

From: Kishore Padmanabha [mailto:kishore.padmanabha@broadcom.com] 
Sent: Tuesday, 14 July 2026 18.49
To: Thomas Monjalon; Morten Brørup
Cc: dev@dpdk.org
Subject: mempool cache change

Hi Thomas,
 
The recent change done as part of BUG ID: 1027, with commit id  https://git.dpdk.org/dpdk/commit/?id=f5e1310f16e0909e7e7f71807123644c63b23cba
Is causing performance drop for the bnxt NIC in 26.07 release.
 
The smaller, shallower cache increases the miss rate, causing refills to hit the shared ring more frequently. 
In the old code, the cache only touched the shared ring when it climbed past 768 instead of 512. That extra 256 elements of headroom allowed significantly more frees to remain local.
 
Could we make the change in config/rte_config.h for RTE_MEMPOOL_CACHE_MAX_SIZE to be 768 instead of 512. Since we use –mbcache=512 as argument for the performance tests.
 
Thanks,
Kishore