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Both use the same block size, but the results of latency and iops are completely different. Why so? You're likely comparing different things: different overheads, different ways of submitting I/O etc. For example: fio is submitting I/O sequentially and requesting block 1 then block 2 etc. Is ioping doing that or is it reading the same offset again and ...


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In terms of how it's implemented, tmpfs uses the same filesystem caching as other Linux filesystems, but the operations to flush data to disk are not implemented, so it's effectively cache only. In practice, this may mean that if your workload never flushes to disk, and fits entirely in memory (the latter would be a requirement to use tmpfs anyway), then ...


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tmpfs, being an extension of the pagecache, really operates as a "transparent" ramdisk. This means it provides very fast sequential read/write speed, but especially fast random IOPs (compared to a storage device). Some examples, collected on an aging Ryzen 1700 with run-of-the-mill memory: dd if=/dev/zero of=test.img bs=1M count=4096 shows 2.8 GB/...


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One number you found is not a substitute for testing. Run your workload on your hardware and check if it is satisfactory. Are you doing small random access I/O, or the entire file? Yes, modern busses and interconnects mean DRAM and NVMe can both drive GB/s class of sequential I/O. It also can be true that certain reads from DRAM are 10x to 100x faster than ...


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