linux-kernel - Re: [PATCH v2 net-next 3/4] net: introduce common dev_page_is

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Message-ID: <752a57a6-3f45-8b9b-e8b1-939bc9450947@nvidia.com>
Date:   Sat, 30 Jan 2021 13:23:30 -0800
From:   John Hubbard <jhubbard@...dia.com>
To:     Alexander Lobakin <alobakin@...me>,
        Jakub Kicinski <kuba@...nel.org>
CC:     "David S. Miller" <davem@...emloft.net>,
        David Rientjes <rientjes@...gle.com>,
        Yisen Zhuang <yisen.zhuang@...wei.com>,
        Salil Mehta <salil.mehta@...wei.com>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Tony Nguyen <anthony.l.nguyen@...el.com>,
        Saeed Mahameed <saeedm@...dia.com>,
        Leon Romanovsky <leon@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Ilias Apalodimas <ilias.apalodimas@...aro.org>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        Willem de Bruijn <willemb@...gle.com>,
        "Randy Dunlap" <rdunlap@...radead.org>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Dexuan Cui <decui@...rosoft.com>,
        Jakub Sitnicki <jakub@...udflare.com>,
        Marco Elver <elver@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <intel-wired-lan@...ts.osuosl.org>,
        <linux-rdma@...r.kernel.org>, <linux-mm@...ck.org>
Subject: Re: [PATCH v2 net-next 3/4] net: introduce common
 dev_page_is_reserved()


On 1/30/21 11:45 AM, Alexander Lobakin wrote:
> From: Jakub Kicinski <kuba@...nel.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