netdev - Re: [PATCH v3] octeontx2-pf: Use the napi_alloc

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Message-ID: <20200509210526.7f0be0c6@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Sat, 9 May 2020 21:05:26 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Kevin Hao <haokexin@...il.com>
Cc:     netdev@...r.kernel.org, Sunil Goutham <sgoutham@...vell.com>,
        Geetha sowjanya <gakula@...vell.com>,
        Subbaraya Sundeep <sbhatta@...vell.com>,
        hariprasad <hkelam@...vell.com>, davem@...emloft.net,
        Sunil Kovvuri <sunil.kovvuri@...il.com>
Subject: Re: [PATCH v3] octeontx2-pf: Use the napi_alloc_frag() to alloc the
 pool buffers

On Sat,  9 May 2020 18:43:10 +0800 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.
> 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 <haokexin@...il.com>

Applied, thank you!