mmap performance and memory use
alc at rice.edu
Tue Oct 25 23:35:36 UTC 2011
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
> 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
> 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
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