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[2003:d8:2f20:da00:b70a:d502:3b51:1f2d]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3e7607cd691sm7166274f8f.32.2025.09.12.08.43.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 12 Sep 2025 08:43:59 -0700 (PDT) Message-ID: Date: Fri, 12 Sep 2025 17:43:56 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v11 00/15] khugepaged: mTHP support To: Kiryl Shutsemau , Pedro Falcato Cc: Johannes Weiner , Nico Pache , linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, ziy@nvidia.com, baolin.wang@linux.alibaba.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, ryan.roberts@arm.com, dev.jain@arm.com, corbet@lwn.net, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, akpm@linux-foundation.org, baohua@kernel.org, willy@infradead.org, peterx@redhat.com, wangkefeng.wang@huawei.com, usamaarif642@gmail.com, sunnanyong@huawei.com, vishal.moola@gmail.com, thomas.hellstrom@linux.intel.com, yang@os.amperecomputing.com, aarcange@redhat.com, raquini@redhat.com, anshuman.khandual@arm.com, catalin.marinas@arm.com, tiwai@suse.de, will@kernel.org, dave.hansen@linux.intel.com, jack@suse.cz, cl@gentwo.org, jglisse@google.com, surenb@google.com, zokeefe@google.com, rientjes@google.com, mhocko@suse.com, rdunlap@infradead.org, hughd@google.com, richard.weiyang@gmail.com, lance.yang@linux.dev, vbabka@suse.cz, rppt@kernel.org, jannh@google.com References: <20250912032810.197475-1-npache@redhat.com> <20250912133701.GA802874@cmpxchg.org> From: David Hildenbrand Content-Language: en-US Autocrypt: addr=david@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit >> Maybe in the Great Glorious Future (how many of those do we have?!) it would >> be a good idea to take this kinds of things into account. Just because we can >> map a THP, doesn't mean we should. >> >> Shower thought: it might be in these cases especially where the FreeBSD >> reservation system comes in handy - best effort allocating a THP, but not >> actually mapping it as such until you really _know_ it is hot - and until >> then, memory reclaim can just break your THP down if it really needs to. > > This is just silly. All downsides without benefit until maybe later. And > for short-lived processes the "later" never comes. Right, that's why I've also been arguing against that (we discussed it recently in the THP cabal). -- Cheers David / dhildenb