From: Andrew Morton <akpm@linux-foundation.org>
To: Muchun Song <songmuchun@bytedance.com>
Cc: corbet@lwn.net, mike.kravetz@oracle.com, mcgrof@kernel.org,
keescook@chromium.org, yzaikin@google.com, osalvador@suse.de,
david@redhat.com, masahiroy@kernel.org,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, duanxiongchun@bytedance.com,
smuchun@gmail.com
Subject: Re: [PATCH v8 4/4] mm: hugetlb_vmemmap: add hugetlb_optimize_vmemmap sysctl
Date: Wed, 13 Apr 2022 12:10:51 -0700 [thread overview]
Message-ID: <20220413121051.a363193c726451115c634a69@linux-foundation.org> (raw)
In-Reply-To: <20220413144748.84106-5-songmuchun@bytedance.com>
On Wed, 13 Apr 2022 22:47:48 +0800 Muchun Song <songmuchun@bytedance.com> wrote:
> We must add hugetlb_free_vmemmap=on (or "off") to the boot cmdline and
> reboot the server to enable or disable the feature of optimizing vmemmap
> pages associated with HugeTLB pages. However, rebooting usually takes a
> long time. So add a sysctl to enable or disable the feature at runtime
> without rebooting.
Do we really need this feature? Really? What's the use case and what
is the end-user value?
Presumably CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP worsens things for some
setups/workloads? Please tell us much more about that. What is the
magnitude of the deoptimization?
next prev parent reply other threads:[~2022-04-13 19:12 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-13 14:47 [PATCH v8 0/4] add hugetlb_optimize_vmemmap sysctl Muchun Song
2022-04-13 14:47 ` [PATCH v8 1/4] mm: hugetlb_vmemmap: introduce CONFIG_HUGETLB_PAGE_HAS_OPTIMIZE_VMEMMAP Muchun Song
2022-04-13 19:08 ` Andrew Morton
2022-04-14 3:10 ` Muchun Song
2022-04-19 6:23 ` Muchun Song
2022-04-20 17:11 ` Masahiro Yamada
2022-04-20 23:30 ` Mike Kravetz
2022-04-21 3:18 ` Muchun Song
2022-04-13 14:47 ` [PATCH v8 2/4] mm: memory_hotplug: override memmap_on_memory when hugetlb_free_vmemmap=on Muchun Song
2022-04-13 14:47 ` [PATCH v8 3/4] mm: hugetlb_vmemmap: use kstrtobool for hugetlb_vmemmap param parsing Muchun Song
2022-04-13 14:47 ` [PATCH v8 4/4] mm: hugetlb_vmemmap: add hugetlb_optimize_vmemmap sysctl Muchun Song
2022-04-13 19:10 ` Andrew Morton [this message]
2022-04-14 4:04 ` Muchun Song
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