Date: Tue, 25 Oct 2011 18:35:17 -0500 From: Alan Cox <alc@rice.edu> To: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl> 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: <4EA747B5.9040304@rice.edu> In-Reply-To: <alpine.BSF.2.00.1110102325220.67653@wojtek.tensor.gdynia.pl> 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> <alpine.BSF.2.00.1110102325220.67653@wojtek.tensor.gdynia.pl>
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On 10/10/2011 4:28 PM, Wojciech Puchar wrote: >> >> 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? > A few minutes ago, I merged the changes to support and document MAP_PREFAULT_READ into 8-STABLE. So, now it exists in HEAD, 9.0, and 8-STABLE. Alan
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