Bill
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I've noticed that an allocation request for a large chunk of memory
(128GB) results in two calls to pages_map() (in src/chunk_mmap.c),
consuming 2x the VM I requested. In a 64 bit world this is not a big
problem, but I've recoded pages_map() to force allocation from an mmap'd
ssd (instead of swap anonymous mmap), and it's forcing me to run out of
backing store. The issue I would like to understand is why pages_map()
is called twice with separate requests for the single 128GB jemalloc()
that I'm doing in my application. The first allocation is followed by a
call to pages_unmap(), but with an unmap size of 0 bytes, leaving it
fully mapped, while the second allocation (which is slightly larger than
128GB) is trimmed to exactly 128GB by 2 subsequent pages_unmap() calls.
This behavior seems very strange to me, and any explanation would be
appreciated.
- double allocations: bill
- Re: double allocations: Jason Evans
