Date: Mon, 10 Oct 2011 23:28:13 +0200 (CEST) From: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl> To: Alan Cox <alc@rice.edu> Cc: alc@freebsd.org, Kostik Belousov <kostikbel@gmail.com>, hackers@freebsd.org, Grzegorz Kulewski <grzegorz@kulewski.pl> Subject: Re: mmap performance and memory use Message-ID: <alpine.BSF.2.00.1110102325220.67653@wojtek.tensor.gdynia.pl> In-Reply-To: <4E8FF4B8.7010300@rice.edu> References: <alpine.BSF.2.00.1110061637270.15552@wojtek.tensor.gdynia.pl> <20111006160159.GQ1511@deviant.kiev.zoral.com.ua> <CAJUyCcMKZ1E5LoJ0BFZju_OH_jjDeqgvBMf8WZ%2BwDvJRFsbH6Q@mail.gmail.com> <alpine.BSF.2.00.1110071916190.8664@wojtek.tensor.gdynia.pl> <4E8FF4B8.7010300@rice.edu>
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> > Notice that vm.pmap.pde.promotions increased by 31. This means that 31 > superpage mappings were created by promotion from small page mappings. thank you. i looked at .mappings as it seemed logical for me that is shows total. > In contrast, vm.pmap.pde.mappings counts superpage mappings that are created > directly and not by promotion from small page mappings. For example, if a > large executable, such as gcc, is resident in memory, the text segment will > be pre-mapped using superpage mappings, avoiding soft fault and promotion > overhead. Similarly, mmap(..., MAP_PREFAULT_READ) on a large, memory > resident file may pre-map the file using superpage mappings. your options are not described in mmap manpage nor madvise (MAP_PREFAULT_READ). when can i find the up to date manpage or description? is it possible to force VM subsystem to operate on superpages when possible - i mean swapping in 2MB chunks?
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