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Tue, 11 Feb 2025 00:41:40 +0000 (UTC) Received: from h1.redhat.com (unknown [10.22.88.129]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 108571800873; Tue, 11 Feb 2025 00:41:29 +0000 (UTC) From: Nico Pache To: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org Cc: ryan.roberts@arm.com, anshuman.khandual@arm.com, catalin.marinas@arm.com, cl@gentwo.org, vbabka@suse.cz, mhocko@suse.com, apopple@nvidia.com, dave.hansen@linux.intel.com, will@kernel.org, baohua@kernel.org, jack@suse.cz, srivatsa@csail.mit.edu, haowenchao22@gmail.com, hughd@google.com, aneesh.kumar@kernel.org, yang@os.amperecomputing.com, peterx@redhat.com, ioworker0@gmail.com, wangkefeng.wang@huawei.com, ziy@nvidia.com, jglisse@google.com, surenb@google.com, vishal.moola@gmail.com, zokeefe@google.com, zhengqi.arch@bytedance.com, jhubbard@nvidia.com, 21cnbao@gmail.com, willy@infradead.org, kirill.shutemov@linux.intel.com, david@redhat.com, aarcange@redhat.com, raquini@redhat.com, dev.jain@arm.com, sunnanyong@huawei.com, usamaarif642@gmail.com, audra@redhat.com, akpm@linux-foundation.org, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, tiwai@suse.de, baolin.wang@linux.alibaba.com, corbet@lwn.net, shuah@kernel.org Subject: [RFC v2 1/5] mm: defer THP insertion to khugepaged Date: Mon, 10 Feb 2025 17:40:50 -0700 Message-ID: <20250211004054.222931-2-npache@redhat.com> In-Reply-To: <20250211004054.222931-1-npache@redhat.com> References: <20250211004054.222931-1-npache@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: B59FCC0002 X-Stat-Signature: 3yjdsyryazik6y6ada1msdfjbkp76rg3 X-Rspam-User: X-HE-Tag: 1739234509-450537 X-HE-Meta: U2FsdGVkX18WS3hAhto4AIxw7oDqfgWDa8Z7Ce4c9lIT0QPB0iUieKyCrE/sNfhhpMhLthkHwmvvM/tJkWDLX8Gr138OPnWZM4AX/GbrauJiFdTxgr4/r7IGZWnnjrVHltlQzP9OQsh/I3QAL6HxaF3nqHWu07CWC7hdUtw+fGWR/fxYVN/j7tUvR3+Wa7rwvD/ZeDbZKb4GLTIcD1iuNC3uWU3OCLRQ8nM9sctSLQEUYulNSO1hOPXfz7tstyj7hGNj5jWCHpSerciAbAyLyj48oWAXB0oTZri0rWfLGBBYNUjrjpafP0rdq+k/KfNolWAGxCdYG2AAyxbL2tgCji56QH7/cpuDZw5iZsf8KDaOlvKfI8vQkODikE5Q1UYYNBQKs0LoqVbFqIwu32PkztI0OJAtGGI7yVen4JvUZdKZq72xoYe3oJispCkA3ns0RSbEPYC4w79rUgG3ixrWlDJ0O/IGlY0H97IWeU5kO7n4hmzinVa0mbAgRbZII/yOuS36r4+Sv6T33QRTE+gTZ9sxwK4Pq5+SjwYpo45qEI7QNHwbr7xFIGUj1a27k0xUCuBeRHOdz6v6pDSZY+o+lzsuFugjDRZzi8ErQSLSuwmdLV3R/GX8HrdeVXqmu1DEjQ+qpQUewzPxtvyfP+lE0a0dOJPRhPMqrmLYpc+Q4jdpRFgQMEEFcDihRHDsoi5fxDEx/EEK8F7HgBp01XJzUi5lkG6/ikD0wRWO9gJa0RO/qD4DNbrosjXmICI9pg2hmAUzf6nzufFy8VAyEG9Ku+pfk5T2TyQ82b1K+Z1RnwfQQRoQwsGtHSj+rXKgBJ1/Kel8i40B+URWXZbeMWleBc7iPi1Tn/775vG+kk0wdpfugtjj3POcJ16mtVjjZs8q0BDEfV+C8Co40p6i+9ev/0bsA9NGtYbqSYF9C95i2qdvCAtWskYb78wHIXqM07K7qCxOD4yL/+2SOXTaAYG fwGyC1oD 65P0OsDm3OxzX7pwkU+FcJZ3p9oj9jZazYzg7AAcDf/+3sXZTrcqWaed9Nx5xQISPOCJbj35M95yIExdltnvKAQyBmO63RJTx8lTF9KyRe8EZ0unHiqUh5BjIqpwM/oW3sc6zFTj8CIq8pbWT0Cy8WHCw/mtYD6BLumWOcLl/DmEAw6HTeS0GzwMgWDTqbghi+DI7v2b2es427c4Tkh/vxjRfvGtcfTmAjaZHMbTzETjVMcMK2oewWnfNlSrlGMwLA+Um2dRnaCF+4vKYaP5GOW5CLOvCSQjjNAfcv8h5HgpXqgTgVegf0QUGxUAVMPJZoEghhYjaRQKxI682VfigF4NsFARqnXRRxTTeTjU+9tOaOyQFNLCDbW+5XLPQt9kD1upZ3Io95BRGJGE= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: setting /transparent_hugepages/enabled=always allows applications to benefit from THPs without having to madvise. However, the pf handler takes very few considerations to decide weather or not to actually use a THP. This can lead to a lot of wasted memory. khugepaged only operates on memory that was either allocated with enabled=always or MADV_HUGEPAGE. Introduce the ability to set enabled=defer, which will prevent THPs from being allocated by the page fault handler unless madvise is set, leaving it up to khugepaged to decide which allocations will collapse to a THP. This should allow applications to benefits from THPs, while curbing some of the memory waste. Signed-off-by: Nico Pache --- include/linux/huge_mm.h | 15 +++++++++++++-- mm/huge_memory.c | 31 +++++++++++++++++++++++++++---- 2 files changed, 40 insertions(+), 6 deletions(-) diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index 93e509b6c00e..fb381ca720ea 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -44,6 +44,7 @@ enum transparent_hugepage_flag { TRANSPARENT_HUGEPAGE_UNSUPPORTED, TRANSPARENT_HUGEPAGE_FLAG, TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, + TRANSPARENT_HUGEPAGE_DEFER_PF_INST_FLAG, TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, @@ -177,6 +178,7 @@ static inline bool hugepage_global_enabled(void) { return transparent_hugepage_flags & ((1<