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[2003:d8:2f18:f900:e0ae:65d5:8bf8:8cfd]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-45e0156b0a8sm175910915e9.3.2025.09.15.03.52.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 15 Sep 2025 03:52:55 -0700 (PDT) Message-ID: Date: Mon, 15 Sep 2025 12:52:53 +0200 Precedence: bulk X-Mailing-List: linux-trace-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: Lorenzo Stoakes Cc: Kiryl Shutsemau , 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, 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, hannes@cmpxchg.org, 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, pfalcato@suse.de References: <20250912032810.197475-1-npache@redhat.com> <2c5328ee-fb6e-45cf-a151-868cc8e7ff97@lucifer.local> <4508810d-7645-4f57-a0c5-2ee9f44206fc@lucifer.local> <34754ca4-fced-4a3c-8ff8-c00967d487de@redhat.com> <92352257-5be4-4aaa-b97f-c4e879ac6959@lucifer.local> From: David Hildenbrand Autocrypt: addr=david@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 15.09.25 12:48, Lorenzo Stoakes wrote: > On Mon, Sep 15, 2025 at 12:44:34PM +0200, David Hildenbrand wrote: >>>>> Mapping that to actual THP sizes (#pages in a thp) on an arch will be easy. >>>> >>>> And at different mTHP levels too right? >>>> >>> >>> Another point here, since we have to keep: >>> >>> /sys/kernel/mm/transparent_hugepage/khugepaged/max_ptes_none >>> >>> Around, and users will try to set values there, presumably we will now add: >>> >>> /sys/kernel/mm/transparent_hugepage/khugepaged/eagerness >>> >>> How will we map <-> the two tunables? >> >> Well, the easy case if someone updates eagerness, then we simply et it to >> whatever magic value we compute and document. >> >> The other direction is more problematic, likely we'll simply warn and do >> something reasonable (map it to whatever eagerness scale is closest or >> simply indicate it as "-1" -- user intervened or sth like that) > > I don't love the idea of a -1 situation, as that's going to create some > confusion. swapiness also has a "max" parameter, so we could just say "override" /" disabled" / whatever? -- Cheers David / dhildenb