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Make hugify system call only when thp=madvise

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When `/sys/kernel/mm/transparent_hugepage/enabled` is always or never it
doesn't make much sense to call `madvise(..., MADV_HUGEPAGE)` and
`madvise(..., MADV_NOHUGEPAGE)`, because it will not have desired effect
anyway, but we'll waste CPU cycles on system call.

Call `madvise(..., MADV_HUGEPAGE)` and `madvise(..., MADV_NOHUGEPAGE)`,
only, when `/sys/kernel/mm/transparent_hugepage/enabled` is set to
`madvise`
This commit is contained in:
Dmitry Ilvokhin 2025-02-18 10:59:10 -08:00
parent 421b17a622
commit f0eefbef3e
1 changed files with 12 additions and 1 deletions
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13
src/hpa_hooks.c
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@ -53,7 +53,15 @@ hpa_hooks_hugify(void *ptr, size_t size, bool sync) {
* hints, when EINVAL is returned it is likely that khugepaged won't be * hints, when EINVAL is returned it is likely that khugepaged won't be
* able to collapse memory range into hugepage either). * able to collapse memory range into hugepage either).
*/ */
bool err = pages_huge(ptr, size); bool err = false;
/*
* It doesn't make much sense to call madvise(..., MADV_HUGEPAGE), when
* transparent_hugepage option is never or always, we'll just waste CPU
* cycles on system call without any effect.
*/
if (init_system_thp_mode == thp_mode_default) {
err = pages_huge(ptr, size);
}
if (sync) { if (sync) {
err = pages_collapse(ptr, size); err = pages_collapse(ptr, size);
} }
@ -62,6 +70,9 @@ hpa_hooks_hugify(void *ptr, size_t size, bool sync) {
static void static void
hpa_hooks_dehugify(void *ptr, size_t size) { hpa_hooks_dehugify(void *ptr, size_t size) {
if (init_system_thp_mode != thp_mode_default) {
return;
}
bool err = pages_nohuge(ptr, size); bool err = pages_nohuge(ptr, size);
(void)err; (void)err;
} }