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Date:   Fri, 8 May 2020 10:18:27 +0530
From:   Sunil Kovvuri <>
To:     Kevin Hao <>
Cc:     Linux Netdev List <>,
        Sunil Goutham <>,
        Geetha sowjanya <>,
        Subbaraya Sundeep <>,
        hariprasad <>,
        "David S. Miller" <>
Subject: Re: [PATCH] octeontx2-pf: Use the napi_alloc_frag() to alloc the pool buffers

On Fri, May 8, 2020 at 9:43 AM Kevin Hao <> wrote:
> In the current codes, the octeontx2 uses its own method to allocate
> the pool buffers, but there are some issues in this implementation.
> 1. We have to run the otx2_get_page() for each allocation cycle and
>    this is pretty error prone. As I can see there is no invocation
>    of the otx2_get_page() in otx2_pool_refill_task(), this will leave
>    the allocated pages have the wrong refcount and may be freed wrongly.

Thanks for pointing, will fix.

> 2. It wastes memory. For example, if we only receive one packet in a
>    NAPI RX cycle, and then allocate a 2K buffer with otx2_alloc_rbuf()
>    to refill the pool buffers and leave the remain area of the allocated
>    page wasted. On a kernel with 64K page, 62K area is wasted.
> IMHO it is really unnecessary to implement our own method for the
> buffers allocate, we can reuse the napi_alloc_frag() to simplify
> our code.
> Signed-off-by: Kevin Hao <>

Have you measured performance with and without your patch ?
I didn't use napi_alloc_frag() as it's too costly, if in one NAPI
instance driver
receives 32 pkts, then 32 calls to napi_alloc_frag() and updates to page ref
count per fragment etc are costly. When traffic rate is less then it
may not matter


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