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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?/FsZzjjwfxxQAT/VC6V4fX5Iv14TLDDeiTeLFuqCYgVVy+B1WFai4nDUjCbn?= =?us-ascii?Q?3QyZtPeRu3wllqbifVsCBo+bvYcuClbD+ThTvypX4VUn4fGn6YaFyM8fNTAv?= =?us-ascii?Q?f61e6tEYefdjhAQNTRLyA/+tC5GMcJGnXAU/cLJ4odjmaoeLomCkCMjCQi2d?= =?us-ascii?Q?Fr2kEH59+Ldr5Fx+vA7dNfYm9sRxBdMGczJ0Mh5UZ0s/gw0Wi/4H8qd0fBtz?= =?us-ascii?Q?B6tSvhyqKoCY+grXiNl6WfGILd3tYdkoPHHZIqsp6vn7dXP1+JkPLTmARkQE?= =?us-ascii?Q?Q9XxBbTz1F/yx8wxSr46oWT8bnHgMZ/OOpPLSbyQKmpktu+XOGmWwaHqGNtq?= =?us-ascii?Q?gVE/gzU2Dd6C6eZ3ZmNNsinSWOFvM5ncb6/Zal7RvOMqankkzMl0o8o/j3PQ?= =?us-ascii?Q?p1DrfP6FOW8RLI3nl6t5G0IjAy39nPXleYBhE+cQyfKq5XObym2qvwX21HFA?= =?us-ascii?Q?Qu0jt/vsSj0/za6DeQhxy0ausJz8Z2BLx/mC2Sv00W0bIpCxHLhN2DvhOhlY?= =?us-ascii?Q?TQARI1Hv9x4DZZyZaxO3aP/iE04VCLYs//J79XPmMsHs+/EuJb8v2Puy5vfn?= =?us-ascii?Q?dgW451GJod5DJdt9ll3WaL/pqOTG7yEHBaZbGL1jtO0QKfhedVXTlSD3STRD?= =?us-ascii?Q?70itKZhrWwfuIZJ0PiClWAYa2Ev7fiGzvuPopTY34tupLX9NBvZx/GixSdzS?= =?us-ascii?Q?ZJ9pMAxiGmDaTbtF598Kqh6ZiGkGH86tpfcvqAVlZjaliZXYI2ThRGjWlNao?= =?us-ascii?Q?zbqEKI4vBGRQ8zaxCVmA3ogdSnn7+v34io7CuT5HizbxOXh2jjJt6hrOOZGX?= =?us-ascii?Q?DWGkvq3w9WzjXtw+XYirWR+NTcTMidy3YUEM+vlYCKkuLMnm6hVJnnr+B9Hz?= =?us-ascii?Q?MS8apf0k/PTXHRShnnSK7PXkbxrEDkNr2faJYmFt9tdlEXtrgCb5Ts5zoVt/?= =?us-ascii?Q?7g0eL+mzTHHZdc9QVX001W+gpSZCRS0gNr0BzEGvXtRSWE0B9oYBztwZgWkG?= =?us-ascii?Q?aOtueKnxHGwS1hRxZ+brMGDqySexW7uJr8BYhlD6YEq9/17KvGRHbXVjuvsb?= =?us-ascii?Q?m3S0ME60MLTOtibr+DBNbuZs1aMMueoo2io6ogipQDMTizTmiYROTEisUNKZ?= =?us-ascii?Q?V1HhPgjv+2HsZnv/r9TYH6INtCa1UhTbOO1TbiKgz97ODs+NWu0js0rcdgKq?= =?us-ascii?Q?MLWMEFx5BzvrSEz+mdUXeg9WvhFqEo+Zia/yyHxBJ6oVxJ98SECjIYawXZLE?= =?us-ascii?Q?dnborqmkAlkU+wUs+qz6xDn62p1mpTSUemjh4JoGtXsfgPc0JTQFh29xn/vl?= =?us-ascii?Q?LxpP4lwG+Z9EUL8HdzDLLSaj+kpz7E6Fr+lmjrXKZ0oeCwjc3X61etseUAZF?= =?us-ascii?Q?wvShCiilYEMrCnvBJsk5l7QLodK/xs8+4l0XZf2vetIRtp2cqmngOqodEgUI?= =?us-ascii?Q?1vSpB+tXKeLemjVaHJE25OlagxniBAaaO0q0m0OJiI3B4uIDmxUq6+/bjZaN?= =?us-ascii?Q?ZGWaoooTPsh7+0wpGybrMkFv4kUWkiZufIbiSZyVFuuPETfpNEjyLigigymz?= =?us-ascii?Q?v/9FTpvKEmH/rOpeOw4=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: ddbf7c4d-288d-491a-d08c-08dcb036a111 X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB5744.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Jul 2024 01:26:25.8229 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: gEGvl4ZD6G+N2gKE10RAZedBixyOXZrtbSTpspCxvTwChTOYH7uaTse6LF5yVtAg X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB6472 --=_MailMate_B6FF6B78-AD9C-4A64-83AE-E41024EBA060_= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable +Kirill On 29 Jul 2024, at 18:27, Nico Pache wrote: > We've seen cases were customers switching from RHEL7 to RHEL8 see a > significant increase in the memory footprint for the same workloads. > > Through our investigations we found that a large contributing factor to= > the increase in RSS was an increase in THP usage. Any knob is changed from RHEL7 to RHEL8 to cause more THP usage? > > For workloads like MySQL, or when using allocators like jemalloc, it is= > often recommended to set /transparent_hugepages/enabled=3Dnever. This i= s > in part due to performance degradations and increased memory waste. > > This series introduces enabled=3Ddefer, this setting acts as a middle > ground between always and madvise. If the mapping is MADV_HUGEPAGE, the= > page fault handler will act normally, making a hugepage if possible. If= > the allocation is not MADV_HUGEPAGE, then the page fault handler will > default to the base size allocation. The caveat is that khugepaged can > still operate on pages thats not MADV_HUGEPAGE. Why? If user does not explicitly want huge page, why bother providing hug= e pages? Wouldn't it increase memory footprint? > > This allows for two things... one, applications specifically designed t= o > use hugepages will get them, and two, applications that don't use > hugepages can still benefit from them without aggressively inserting > THPs at every possible chance. This curbs the memory waste, and defers > the use of hugepages to khugepaged. Khugepaged can then scan the memory= > for eligible collapsing. khugepaged would replace application memory with huge pages without speci= fic goal. Why not use a user space agent with process_madvise() to collapse huge pages? Admin might have more knobs to tweak than khugepaged. > > Admins may want to lower max_ptes_none, if not, khugepaged may > aggressively collapse single allocations into hugepages. > > RFC note > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > Im not sure if im missing anything related to the mTHP > changes. I think now that we have hugepage_pmd_enabled in > commit 00f58104202c ("mm: fix khugepaged activation policy") everything= > should work as expected. > > Nico Pache (2): > mm: defer THP insertion to khugepaged > mm: document transparent_hugepage=3Ddefer usage > > Documentation/admin-guide/mm/transhuge.rst | 18 ++++++++++--- > include/linux/huge_mm.h | 15 +++++++++-- > mm/huge_memory.c | 31 +++++++++++++++++++---= > 3 files changed, 55 insertions(+), 9 deletions(-) > > Cc: Andrew Morton > Cc: David Hildenbrand > Cc: Matthew Wilcox > Cc: Barry Song > Cc: Ryan Roberts > Cc: Baolin Wang > Cc: Lance Yang > Cc: Peter Xu > Cc: Zi Yan > Cc: Rafael Aquini > Cc: Andrea Arcangeli > Cc: Jonathan Corbet > -- = > 2.45.2 -- Best Regards, Yan, Zi --=_MailMate_B6FF6B78-AD9C-4A64-83AE-E41024EBA060_= Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iQJDBAEBCgAtFiEE6rR4j8RuQ2XmaZol4n+egRQHKFQFAmaoQT0PHHppeUBudmlk aWEuY29tAAoJEOJ/noEUByhUcXcP/jROEHwfShbTn9Fn9nIOL34PqgT1WCbf6rCE X3JSTsjBgzPfvpCdJlYDhMkAnjhuXJFcAEsQbvzC8RvCnPkA6ndti1RD0QzWbTc9 hkL+oMYfXEMk3f/oaxt7ZGvVcLqF2TUC0nDLXVjpNZC8pMw6SdzJBMO8iwtYOrRI uFRpDAhI9HsTlxmMwGPh6EO5PIZ9mTrWoSIHEhhVZDQdLziLVgBxt+Uondb1LXG3 AbUb0XPztAevp1lYQycb22wUOTpDwISaAQhAxSkBkuv9wBiK0EizI1OZTqI7pdhn DurRt9SHriVcgIJKi7kwItxFNtyvxdKdMHFxWndc1CS7elbPObRUtMNZNDSBdwYw iH0J30bdw/DUsaq1XzSN5gJjYBz4s5uF81hBJnl/7dsFd8kI098aZfrqJ3DxON+F V1g+SLapnR6Y4cXpSe2Mo2Xe0p0MQfe/8ttIU4RLouZW8XzuNDpewgI6RqbQm5xo DQ7pb21v0tWPvZ6D1GPW2r7d4tk5/WAj4mcye6OkS+vbkC4AFfP5yf5HVZ8GUHD+ TU4iI9nHTdrB6W5Bfzi/c6DvPB2hnu41gmw3P8stMD6WuWGVs5n5d/fQrlRKSgQG GOOSbsAe+QnIrQJZz0BAgasTD/YaTk5DcokAhhCgriRyWLclJ5P9oMjE6d9l5EHe JTAQkGwD =UPbo -----END PGP SIGNATURE----- --=_MailMate_B6FF6B78-AD9C-4A64-83AE-E41024EBA060_=--