* Re: Avoid reading /sys/kernel/mm/transparent_hugepage/?
[not found] <CAMe9rOrk20jCXO_Bun4LK6M3fd_8HzEtAu94FW+-xSkwNiOt7w@mail.gmail.com>
@ 2026-04-10 7:27 ` Florian Weimer
2026-04-10 7:40 ` H.J. Lu
0 siblings, 1 reply; 4+ messages in thread
From: Florian Weimer @ 2026-04-10 7:27 UTC (permalink / raw)
To: H.J. Lu; +Cc: GNU C Library, Alexey Dobriyan, linux-kernel, linux-arch,
linux-api
* H. J. Lu:
> To enable THP segment load, ld.so opens and reads 2 files under
> /sys/kernel/mm/transparent_hugepage/. This requires mounting
> /sys and is expensive. Is it possible to put such info in vDSO?
Alexey Dobriyan proposed adding AT_PAGE_SHIFT_LIST to the auxiliary
vector a while back, but I don't know the status of that.
Thanks,
Florian
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Avoid reading /sys/kernel/mm/transparent_hugepage/?
2026-04-10 7:27 ` Avoid reading /sys/kernel/mm/transparent_hugepage/? Florian Weimer
@ 2026-04-10 7:40 ` H.J. Lu
2026-04-10 8:37 ` Alexey Dobriyan
0 siblings, 1 reply; 4+ messages in thread
From: H.J. Lu @ 2026-04-10 7:40 UTC (permalink / raw)
To: Florian Weimer
Cc: GNU C Library, Alexey Dobriyan, linux-kernel, linux-arch,
linux-api
On Fri, Apr 10, 2026 at 3:28 PM Florian Weimer <fweimer@redhat.com> wrote:
>
> * H. J. Lu:
>
> > To enable THP segment load, ld.so opens and reads 2 files under
> > /sys/kernel/mm/transparent_hugepage/. This requires mounting
> > /sys and is expensive. Is it possible to put such info in vDSO?
>
> Alexey Dobriyan proposed adding AT_PAGE_SHIFT_LIST to the auxiliary
Does it cover
[hjl@gnu-tgl-3 linux]$ cat /sys/kernel/mm/transparent_hugepage/hpage_pmd_size
2097152
[hjl@gnu-tgl-3 linux]$
> vector a while back, but I don't know the status of that.
>
How can we get
[hjl@gnu-tgl-3 linux]$ cat /sys/kernel/mm/transparent_hugepage/enabled
always [madvise] never
[hjl@gnu-tgl-3 linux]$
--
H.J.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Avoid reading /sys/kernel/mm/transparent_hugepage/?
2026-04-10 7:40 ` H.J. Lu
@ 2026-04-10 8:37 ` Alexey Dobriyan
2026-04-11 0:12 ` H.J. Lu
0 siblings, 1 reply; 4+ messages in thread
From: Alexey Dobriyan @ 2026-04-10 8:37 UTC (permalink / raw)
To: H.J. Lu; +Cc: Florian Weimer, GNU C Library, linux-kernel, linux-arch,
linux-api
On Fri, Apr 10, 2026 at 03:40:30PM +0800, H.J. Lu wrote:
> On Fri, Apr 10, 2026 at 3:28 PM Florian Weimer <fweimer@redhat.com> wrote:
> >
> > * H. J. Lu:
> >
> > > To enable THP segment load, ld.so opens and reads 2 files under
> > > /sys/kernel/mm/transparent_hugepage/. This requires mounting
> > > /sys and is expensive. Is it possible to put such info in vDSO?
> >
> > Alexey Dobriyan proposed adding AT_PAGE_SHIFT_LIST to the auxiliary
>
> Does it cover
>
> [hjl@gnu-tgl-3 linux]$ cat /sys/kernel/mm/transparent_hugepage/hpage_pmd_size
> 2097152
> [hjl@gnu-tgl-3 linux]$
>
> > vector a while back, but I don't know the status of that.
Status: nothing happened.
> How can we get
>
> [hjl@gnu-tgl-3 linux]$ cat /sys/kernel/mm/transparent_hugepage/enabled
> always [madvise] never
> [hjl@gnu-tgl-3 linux]$
This is not covered, see the link:
https://lore.kernel.org/lkml/ecb049aa-bcac-45c7-bbb1-4612d094935a@p183/
PAGE_SHIFT_MASK should be folded into system call probably.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Avoid reading /sys/kernel/mm/transparent_hugepage/?
2026-04-10 8:37 ` Alexey Dobriyan
@ 2026-04-11 0:12 ` H.J. Lu
0 siblings, 0 replies; 4+ messages in thread
From: H.J. Lu @ 2026-04-11 0:12 UTC (permalink / raw)
To: Alexey Dobriyan
Cc: Florian Weimer, GNU C Library, linux-kernel, linux-arch,
linux-api
On Fri, Apr 10, 2026 at 4:35 PM Alexey Dobriyan <adobriyan@gmail.com> wrote:
>
> On Fri, Apr 10, 2026 at 03:40:30PM +0800, H.J. Lu wrote:
> > On Fri, Apr 10, 2026 at 3:28 PM Florian Weimer <fweimer@redhat.com> wrote:
> > >
> > > * H. J. Lu:
> > >
> > > > To enable THP segment load, ld.so opens and reads 2 files under
> > > > /sys/kernel/mm/transparent_hugepage/. This requires mounting
> > > > /sys and is expensive. Is it possible to put such info in vDSO?
> > >
> > > Alexey Dobriyan proposed adding AT_PAGE_SHIFT_LIST to the auxiliary
> >
> > Does it cover
> >
> > [hjl@gnu-tgl-3 linux]$ cat /sys/kernel/mm/transparent_hugepage/hpage_pmd_size
> > 2097152
> > [hjl@gnu-tgl-3 linux]$
> >
> > > vector a while back, but I don't know the status of that.
>
> Status: nothing happened.
>
> > How can we get
> >
> > [hjl@gnu-tgl-3 linux]$ cat /sys/kernel/mm/transparent_hugepage/enabled
> > always [madvise] never
> > [hjl@gnu-tgl-3 linux]$
>
> This is not covered, see the link:
> https://lore.kernel.org/lkml/ecb049aa-bcac-45c7-bbb1-4612d094935a@p183/
>
> PAGE_SHIFT_MASK should be folded into system call probably.
We need a fast way to check THP status for THP segment load.
A system call to return /sys/kernel/mm/transparent_hugepage/enabled
and /sys/kernel/mm/transparent_hugepage/hpage_pmd_size should
work.
--
H.J.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2026-04-10 7:27 ` Avoid reading /sys/kernel/mm/transparent_hugepage/? Florian Weimer
2026-04-10 7:40 ` H.J. Lu
2026-04-10 8:37 ` Alexey Dobriyan
2026-04-11 0:12 ` H.J. Lu
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