linux-kernel - Re: [RFC PATCH v1 3/4] mm: Override mTHP "enabled" defaults at kernel cmdline

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Message-ID: <3551520d-d81d-40d7-8651-f55e642d24dc@redhat.com>
Date: Fri, 19 Jul 2024 10:29:18 +0200
From: David Hildenbrand <david@...hat.com>
To: Barry Song <baohua@...nel.org>, Ryan Roberts <ryan.roberts@....com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, Hugh Dickins
 <hughd@...gle.com>, Jonathan Corbet <corbet@....net>,
 "Matthew Wilcox (Oracle)" <willy@...radead.org>,
 Lance Yang <ioworker0@...il.com>, Baolin Wang
 <baolin.wang@...ux.alibaba.com>, Gavin Shan <gshan@...hat.com>,
 Pankaj Raghav <kernel@...kajraghav.com>, Daniel Gomez
 <da.gomez@...sung.com>, linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [RFC PATCH v1 3/4] mm: Override mTHP "enabled" defaults at kernel
 cmdline

On 19.07.24 09:52, Barry Song wrote:
> On Fri, Jul 19, 2024 at 7:48 PM Ryan Roberts <ryan.roberts@....com> wrote:
>>
>> On 19/07/2024 01:46, Barry Song wrote:
>>> On Wed, Jul 17, 2024 at 7:13 PM Ryan Roberts <ryan.roberts@....com> wrote:
>>>>
>>>> Add thp_anon= cmdline parameter to allow specifying the default
>>>> enablement of each supported anon THP size. The parameter accepts the
>>>> following format and can be provided multiple times to configure each
>>>> size:
>>>>
>>>> thp_anon=<size>[KMG]:<value>
>>>>
>>>> See Documentation/admin-guide/mm/transhuge.rst for more details.
>>>>
>>>> Configuring the defaults at boot time is useful to allow early user
>>>> space to take advantage of mTHP before its been configured through
>>>> sysfs.
>>>
>>> This is exactly what I need and want to implement, as the current behavior
>>> is problematic. We need to boot up the system and reach the point where
>>> we can set up the sys interfaces to enable mTHP. Many processes miss the
>>> opportunity to use mTHP.
>>>
>>> On the other hand, userspace might have been tuned to detect that mTHP
>>> is enabled, such as a .so library. However, it turns out we have had
>>> inconsistent settings between the two stages - before and after setting
>>> mTHP enabled by sys interfaces.
>>
>> Good feedback - sounds like I should separate out this patch from the rest of
>> the series to get it reviewed and merged faster?
> 
> +1

Agreed, this is reasonable to have.

-- 
Cheers,

David / dhildenb