Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Sat, 30 Jan 2021 11:07:07 -0800
From:   Jakub Kicinski <kuba@kernel.org>
To:     Alexander Lobakin <alobakin@pm.me>
Cc:     "David S. Miller" <davem@davemloft.net>,
        David Rientjes <rientjes@google.com>,
        Yisen Zhuang <yisen.zhuang@huawei.com>,
        Salil Mehta <salil.mehta@huawei.com>,
        Jesse Brandeburg <jesse.brandeburg@intel.com>,
        Tony Nguyen <anthony.l.nguyen@intel.com>,
        Saeed Mahameed <saeedm@nvidia.com>,
        Leon Romanovsky <leon@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Jesper Dangaard Brouer <brouer@redhat.com>,
        Ilias Apalodimas <ilias.apalodimas@linaro.org>,
        Jonathan Lemon <jonathan.lemon@gmail.com>,
        Willem de Bruijn <willemb@google.com>,
        Randy Dunlap <rdunlap@infradead.org>,
        Pablo Neira Ayuso <pablo@netfilter.org>,
        Dexuan Cui <decui@microsoft.com>,
        Jakub Sitnicki <jakub@cloudflare.com>,
        Marco Elver <elver@google.com>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, intel-wired-lan@lists.osuosl.org,
        linux-rdma@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v2 net-next 3/4] net: introduce common
 dev_page_is_reserved()
Message-ID: <20210130110707.3122a360@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
In-Reply-To: <20210130154149.8107-1-alobakin@pm.me>
References: <20210127201031.98544-1-alobakin@pm.me>
        <20210127201031.98544-4-alobakin@pm.me>
        <20210129183907.2ae5ca3d@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
        <20210130154149.8107-1-alobakin@pm.me>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Sat, 30 Jan 2021 15:42:29 +0000 Alexander Lobakin wrote:
> > On Wed, 27 Jan 2021 20:11:23 +0000 Alexander Lobakin wrote:  
> > > + * dev_page_is_reserved - check whether a page can be reused for network Rx
> > > + * @page: the page to test
> > > + *
> > > + * A page shouldn't be considered for reusing/recycling if it was allocated
> > > + * under memory pressure or at a distant memory node.
> > > + *
> > > + * Returns true if this page should be returned to page allocator, false
> > > + * otherwise.
> > > + */
> > > +static inline bool dev_page_is_reserved(const struct page *page)  
> > 
> > Am I the only one who feels like "reusable" is a better term than
> > "reserved".  
> 
> I thought about it, but this will need to inverse the conditions in
> most of the drivers. I decided to keep it as it is.
> I can redo if "reusable" is preferred.

Naming is hard. As long as the condition is not a double negative it
reads fine to me, but that's probably personal preference.
The thing that doesn't sit well is the fact that there is nothing
"reserved" about a page from another NUMA node.. But again, if nobody
+1s this it's whatever...

That said can we move the likely()/unlikely() into the helper itself?
People on the internet may say otherwise but according to my tests 
using __builtin_expect() on a return value of a static inline helper
works just fine.