Re: [PATCH v2 net-next 3/4] net: introduce common dev_page_is_reserved()

From: John Hubbard <jhubbard@nvidia.com>
To: Alexander Lobakin <alobakin@pm.me>, Jakub Kicinski <kuba@kernel.org>
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()
Date: Sat, 30 Jan 2021 13:23:30 -0800	[thread overview]
Message-ID: <752a57a6-3f45-8b9b-e8b1-939bc9450947@nvidia.com> (raw)
In-Reply-To: <20210130194459.37837-1-alobakin@pm.me>

On 1/30/21 11:45 AM, Alexander Lobakin wrote:
> From: Jakub Kicinski <kuba@kernel.org>
> Date: Sat, 30 Jan 2021 11:07:07 -0800
> 
>> 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...
> 
> Agree on NUMA and naming. I'm a bit surprised that 95% of drivers
> have this helper called "reserved" (one of the reasons why I finished
> with this variant).
> Let's say, if anybody else will vote for "reusable", I'll pick it for
> v3.

Definitely "reusable" seems better to me, and especially anything *other*
than "reserved" is a good idea, IMHO.

thanks,
-- 
John Hubbard
NVIDIA