netdev - Re: [PATCH net-next] net: skb: introduce and use a single page frag cache

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Message-ID: <791065bb090ffe08f170e91bd7fabe0a5660ab53.camel@redhat.com>
Date:   Thu, 22 Sep 2022 18:29:11 +0200
From:   Paolo Abeni <pabeni@...hat.com>
To:     Alexander Duyck <alexander.duyck@...il.com>
Cc:     netdev@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Subject: Re: [PATCH net-next] net: skb: introduce and use a single page frag
 cache

On Wed, 2022-09-21 at 14:44 -0700, Alexander Duyck wrote:
> On Wed, Sep 21, 2022 at 1:52 PM Paolo Abeni <pabeni@...hat.com> wrote:
> > In that case we will still duplicate a bit of code  -
> > this_cpu_ptr(&napi_alloc_cache) on both branches. gcc 11.3.1 here says
> > that the generated code is smaller without this change.
> 
> Why do you need to duplicate it? 

The goal was using a single local variable to track the napi cache and
the memory info. I thought ("was sure") that keeping two separate
variables ('nc' and 'page_frag' instead of 'nc' and 'pfmemalloc') would
produce the same amount of code. gcc says I'm wrong and you are right
;)

I'll use that in v2, thanks!

Paolo