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Sat, 18 Mar 2023 12:58:20 +0000 From: David Laight To: 'Matthew Wilcox' , Mike Kravetz CC: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" Subject: RE: THP backed thread stacks Thread-Topic: THP backed thread stacks Thread-Index: AQHZWPlZJwMTNLTeV0WLE6c5qQ1d3K8AfxPA Date: Sat, 18 Mar 2023 12:58:20 +0000 Message-ID: <9725accc24aa4d76b01cdc9b210d12d4@AcuMS.aculab.com> References: <20230306235730.GA31451@monkey> In-Reply-To: Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: D6B0A40013 X-Rspam-User: X-Stat-Signature: fodbpsrthj5kz4eyr9y3166exkhy3cmm X-HE-Tag: 1679144305-290763 X-HE-Meta: U2FsdGVkX1/dKDFQVi/TbGSa+hNYQyPbjrdnC3lP5dJMCDqNHuj3mv3Ht0WeXTZhDFGT2W0x/bWIfYtrdMtzCsbQu3uykRd9fz+rFxKvz1dJFK88Or0Ka9w9aXUa7Qij7pcT7ce/TZujiCF4m91AJVSSNHG2fzYky92SRCyAlDdAqeoX48BXFe1es3QHVTX8M139h8LgfBoZlwT1bb8F1pXJ1ZJge5ZiP7VSfnsRuljebadesX1DaoUrcpIfL+P5LcstxwSyLRUbJ21J3+nas0n0ZVV9ajCLiU+C3wRJqim/MMOkduBO+g9RY3tHF3qkXvR6OyPmWrfaQwNnQx0TL0FIuCQ/6rnibxTC9tL5cciEb/TbnPQOZHz/hYIBXe/T9NN0csQTi59iqF1P7loAH5QWgSniOy434CjJGuR3QOt3n45Y5XMcR+dJpx3JhjkFb94c+gkcBrcvwRFnQPxxHeQXfD3eYXSkQPa9819uz2xQoh2HWqKWdCTXwSKHrw2hLX4ucqdQ+3L7y016Fd2sWqsoZDVLhFonixLLOMuhmT3jvFgIgK3uMQIDVXT/np4M3Zg1m4DWjVa61UQFYOkoDUvf/FNqq3jdH2CYuGuNcVrNKlnyaAxnETOg8XfDfLkPsiz5HGOEWDqQPGxAPDVRiMSMlt1ucQ7uW9pwsQhfFGM719EOoFHaBXv+odl+V46vbplaI6upoPPodC+y61fSlEP+HzHuINJ0WIuncOPOMh5FDMQWVNmYeJyPIVNlvpHrlMSdHw3ooPSctGxNKZZvTs5iW6im1uoRV+38kLVkSdTiQ91i7iSaki78wImWyY7FjrkqfMV6h/+K07SUHS9SlaCMn/NAM/kOKS2HDFNllkGi4MOR5496vjTznB/+pA2JdBgjK9RXdbxk8YhSUgGB3quN7vMafZEw+nVc0kjKQ/52haJ+L3ShrakFUCBKdx5XigFH/pWUxIACFeYAVfM U3/ak0op TP0ePh5p2zeunDU25iiRjPsPlKQqgj12YxkTet4rYF0JDWMcrliL+KwjsdQ5CZYBhHfgc6xWK1u0fXIEJa8N/wbsVhimTJuRmqpHhKHpK04AwSWuKfmOvojFMRhbeg+RPZqBCXMEp5JAfh91C+Y7kTo2vB8yWTzISho/jHjNG7oeT2uJljYBbTbRewoY0uQVZaE0guF/3i+3cmMtzaBAEDzLMKKfo/2o5Y7txRE0qBin0ajMlOWMF9Pk8gw== 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: From: Matthew Wilcox > Sent: 17 March 2023 17:53 ... > My understanding is that for a normal app (like, say, 'cat'), we'll > allow up to an 8MB stack, but we only create a VMA that is 4kB in size > and set the VM_GROWSDOWN flag on it (to allow it to magically grow). > Therefore we won't create a 2MB page because the VMA is too small. Is there anyway that glibc (or anything else) could request that for a thread stack? It would make the process 'memory size' reported by ps/top much more meaningful for programs with threads. I've noticed some (what should be) small programs having a size (rss?) of 277m. I'm sure a lot of it is thread stack. =09David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1= PT, UK Registration No: 1397386 (Wales)