Re: [PATCH v2] net: mana: Use page pool fragments for RX buffers instead of full pages to improve memory efficiency.

[Dipayaan Roy]

On Tue, Jul 29, 2025 at 12:15:23PM +0200, Jesper Dangaard Brouer wrote:
> 
> 
> On 23/07/2025 21.07, Dipayaan Roy wrote:
> >This patch enhances RX buffer handling in the mana driver by allocating
> >pages from a page pool and slicing them into MTU-sized fragments, rather
> >than dedicating a full page per packet. This approach is especially
> >beneficial on systems with large page sizes like 64KB.
> >
> >Key improvements:
> >
> >- Proper integration of page pool for RX buffer allocations.
> >- MTU-sized buffer slicing to improve memory utilization.
> >- Reduce overall per Rx queue memory footprint.
> >- Automatic fallback to full-page buffers when:
> >    * Jumbo frames are enabled (MTU > PAGE_SIZE / 2).
> >    * The XDP path is active, to avoid complexities with fragment reuse.
> >- Removal of redundant pre-allocated RX buffers used in scenarios like MTU
> >   changes, ensuring consistency in RX buffer allocation.
> >
> >Testing on VMs with 64KB pages shows around 200% throughput improvement.
> >Memory efficiency is significantly improved due to reduced wastage in page
> >allocations. Example: We are now able to fit 35 rx buffers in a single 64kb
> >page for MTU size of 1500, instead of 1 rx buffer per page previously.
> >
> >Tested:
> >
> >- iperf3, iperf2, and nttcp benchmarks.
> >- Jumbo frames with MTU 9000.
> >- Native XDP programs (XDP_PASS, XDP_DROP, XDP_TX, XDP_REDIRECT) for
> >   testing the XDP path in driver.
> >- Page leak detection (kmemleak).
> >- Driver load/unload, reboot, and stress scenarios.
> 
> Chris (Cc) discovered a crash/bug[1] with page pool fragments used
> from the mlx5 driver.
> He put together a BPF program that reproduces the issue here:
> - [2] https://github.com/arges/xdp-redirector
> 
> Can I ask you to test that your driver against this reproducer?
> 
> 
> [1] https://lore.kernel.org/all/aIEuZy6fUj_4wtQ6@861G6M3/
> 
> --Jesper
>

Hi Jesper,

I was unable to reproduce this issue on mana driver.


Regards
Dipayaan Roy