From: Baolin Wang <baolin.wang@linux.alibaba.com>
To: Ryan Roberts <ryan.roberts@arm.com>,
akpm@linux-foundation.org, hughd@google.com
Cc: willy@infradead.org, david@redhat.com, ioworker0@gmail.com,
wangkefeng.wang@huawei.com, ying.huang@intel.com,
21cnbao@gmail.com, shy828301@gmail.com, ziy@nvidia.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 5/8] mm: shmem: add multi-size THP sysfs interface for anonymous shmem
Date: Wed, 8 May 2024 12:45:09 +0800 [thread overview]
Message-ID: <0b3735bc-2ad7-44f8-808b-37fc90d57199@linux.alibaba.com> (raw)
In-Reply-To: <30329a82-45b9-4e78-8c48-bd56af113786@arm.com>
On 2024/5/7 18:52, Ryan Roberts wrote:
> On 06/05/2024 09:46, Baolin Wang wrote:
>> To support the use of mTHP with anonymous shmem, add a new sysfs interface
>> 'shmem_enabled' in the '/sys/kernel/mm/transparent_hugepage/hugepages-kB/'
>> directory for each mTHP to control whether shmem is enabled for that mTHP,
>> with a value similar to the top level 'shmem_enabled', which can be set to:
>> "always", "inherit (to inherit the top level setting)", "within_size", "advise",
>> "never", "deny", "force". These values follow the same semantics as the top
>> level, except the 'deny' is equivalent to 'never', and 'force' is equivalent
>> to 'always' to keep compatibility.
>
> We decided at [1] to not allow 'force' for non-PMD-sizes.
>
> [1]
> https://lore.kernel.org/linux-mm/533f37e9-81bf-4fa2-9b72-12cdcb1edb3f@redhat.com/
>
> However, thinking about this a bit more, I wonder if the decision we made to
> allow all hugepages-xxkB/enabled controls to take "inherit" was the wrong one.
> Perhaps we should have only allowed the PMD-sized enable=inherit (this is just
> for legacy back compat after all, I don't think there is any use case where
> changing multiple mTHP size controls atomically is actually useful). Applying
Agree. This is also our usage of 'inherit'.
> that pattern here, it means the top level can always take "force" without any
> weird error checking. And we would allow "force" on the PMD-sized control but
> not on the others - again this is easy to error check.
>
> Does this pattern make more sense? If so, is it too late to change
> hugepages-xxkB/enabled interface?
IMO, this sounds reasonable to me. Let's see what others think, David?
next prev parent reply other threads:[~2024-05-08 4:45 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-06 8:46 [PATCH 0/8] add mTHP support for anonymous shmem Baolin Wang
2024-05-06 8:46 ` [PATCH 1/8] mm: move highest_order() and next_order() out of the THP config Baolin Wang
2024-05-07 10:21 ` Ryan Roberts
2024-05-08 2:13 ` Baolin Wang
2024-05-08 9:06 ` Ryan Roberts
2024-05-08 9:40 ` Baolin Wang
2024-05-06 8:46 ` [PATCH 2/8] mm: memory: extend finish_fault() to support large folio Baolin Wang
2024-05-07 10:37 ` Ryan Roberts
2024-05-08 3:44 ` Baolin Wang
2024-05-08 7:15 ` David Hildenbrand
2024-05-08 9:06 ` Baolin Wang
2024-05-08 8:53 ` Ryan Roberts
2024-05-08 9:31 ` Baolin Wang
2024-05-08 10:47 ` Ryan Roberts
2024-05-09 1:10 ` Baolin Wang
2024-05-06 8:46 ` [PATCH 3/8] mm: shmem: add an 'order' parameter for shmem_alloc_hugefolio() Baolin Wang
2024-05-06 8:46 ` [PATCH 4/8] mm: shmem: add THP validation for PMD-mapped THP related statistics Baolin Wang
2024-05-06 8:46 ` [PATCH 5/8] mm: shmem: add multi-size THP sysfs interface for anonymous shmem Baolin Wang
2024-05-07 10:52 ` Ryan Roberts
2024-05-08 4:45 ` Baolin Wang [this message]
2024-05-08 7:08 ` David Hildenbrand
2024-05-08 7:12 ` David Hildenbrand
2024-05-08 9:02 ` Ryan Roberts
2024-05-08 9:56 ` Baolin Wang
2024-05-08 10:48 ` Ryan Roberts
2024-05-08 12:02 ` David Hildenbrand
2024-05-08 12:10 ` David Hildenbrand
2024-05-08 12:43 ` Ryan Roberts
2024-05-08 12:44 ` Ryan Roberts
2024-05-08 12:45 ` David Hildenbrand
2024-05-08 12:54 ` Ryan Roberts
2024-05-08 13:07 ` David Hildenbrand
2024-05-08 13:44 ` Ryan Roberts
2024-05-06 8:46 ` [PATCH 6/8] mm: shmem: add mTHP support " Baolin Wang
2024-05-07 10:46 ` kernel test robot
2024-05-08 6:03 ` Baolin Wang
2024-05-06 8:46 ` [PATCH 7/8] mm: shmem: add mTHP size alignment in shmem_get_unmapped_area Baolin Wang
2024-05-06 8:46 ` [PATCH 8/8] mm: shmem: add mTHP counters for anonymous shmem Baolin Wang
2024-05-06 10:54 ` [PATCH 0/8] add mTHP support " Lance Yang
2024-05-07 1:47 ` Baolin Wang
2024-05-07 6:50 ` Lance Yang
2024-05-07 10:20 ` Ryan Roberts
2024-05-08 5:45 ` Baolin Wang
[not found] ` <CGME20240508113934eucas1p13a3972f3f9955365f40155e084a7c7d5@eucas1p1.samsung.com>
2024-05-08 11:39 ` Daniel Gomez
2024-05-08 11:58 ` David Hildenbrand
2024-05-08 14:28 ` Daniel Gomez
2024-05-08 17:03 ` David Hildenbrand
2024-05-09 19:18 ` Daniel Gomez
2024-05-09 3:08 ` Baolin Wang
2024-05-08 19:23 ` Luis Chamberlain
2024-05-09 17:48 ` David Hildenbrand
2024-05-10 18:53 ` Luis Chamberlain
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