Re:Why mmap is faster than system calls (2019)
by silon42 on Saturday January 09, 2021 @03:01PM
(#25704107)
mmap has less deterministic memory pressure and more complex interactions with overcommit (if enabled).
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Re:Why mmap is faster than system calls (2019)
by __turbobrew__ on Saturday January 09, 2021 @06:06PM
(#25706012)
I write software for a HPC centre and we noticed this as well. The speed of our programs heavily using memory maps can vary by an order of magnitude based upon the memory pressure on the node.
This non-determinism in runtime is a show stopper for us so we ripped out most memory maps from our codebase. There is just too much magic happening under the hood to have control over your program.