From: David Rientjes <rientjes@google.com>
To: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: rppt@kernel.org, akpm@linux-foundation.org, mhocko@suse.com,
vbabka@suse.cz, david@redhat.com, quic_charante@quicinc.com,
lizhe.67@bytedance.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [PATCH v4] mm/page_ext: Do not allocate space for page_ext->flags if not needed
Date: Tue, 17 Jan 2023 21:56:36 -0800 (PST) [thread overview]
Message-ID: <59557eaf-7301-d142-4549-c3e196d011d5@google.com> (raw)
In-Reply-To: <20230117202103.1412449-1-pasha.tatashin@soleen.com>
On Tue, 17 Jan 2023, 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 kernel-doc comment before page_ext_operations that describes
> the fields, 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>
> Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
prev parent reply other threads:[~2023-01-18 5:56 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-17 20:21 Pasha Tatashin
2023-01-18 5:53 ` Mike Rapoport
2023-01-18 5:56 ` David Rientjes [this message]
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