From: David Hildenbrand <david@redhat.com>
To: Vlastimil Babka <vbabka@suse.cz>,
Pasha Tatashin <pasha.tatashin@soleen.com>,
akpm@linux-foundation.org, mhocko@suse.com,
quic_charante@quicinc.com, lizhe.67@bytedance.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Mike Rapoport <rppt@linux.ibm.com>
Subject: Re: [PATCH v3] mm/page_ext: Do not allocate space for page_ext->flags if not needed
Date: Mon, 16 Jan 2023 11:53:00 +0100 [thread overview]
Message-ID: <916aedc8-1d0b-a0f9-5ddf-6c6305e7cbdb@redhat.com> (raw)
In-Reply-To: <0c706897-b2cc-714c-c72e-4154b1f3f52b@suse.cz>
On 16.01.23 11:51, Vlastimil Babka wrote:
> On 1/13/23 16:42, Pasha Tatashin wrote:
>> There is 8 byte page_ext->flags field allocated per page whenever
>> CONFIG_PAGE_EXTENSION is enabled. However, not every user of page_ext
>> uses flags. Therefore, check whether flags is needed at least by one
>> user and if so allocate space for it.
>>
>> For example when page_table_check is enabled, on a machine with 128G
>> of memory before the fix:
>>
>> [ 2.244288] allocated 536870912 bytes of page_ext
>> after the fix:
>> [ 2.160154] allocated 268435456 bytes of page_ext
>>
>> Also, add a comment before page_ext_operations that describes the
>> field, and remove check if need() is set, as that is now a required
>> field.
>>
>> Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
>
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
>
> Mike's comments look reasonable to me.
Seconded
Acked-by: David Hildenbrand <david@redhat.com>
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2023-01-16 10:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-13 15:42 Pasha Tatashin
2023-01-16 9:00 ` Mike Rapoport
2023-01-17 20:04 ` Pasha Tatashin
2023-01-16 10:51 ` Vlastimil Babka
2023-01-16 10:53 ` David Hildenbrand [this message]
2023-01-17 20:05 ` Pasha Tatashin
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