I made a tmpfs filesystem in my home directory on Ubuntu using this command: Then I wrote this Python program: The result: I am confused about this result. Isn’t the tmpfs a file system based on RAM and isn’t RAM supposed to be notably faster than any hard disk, including SSDs? Furthermore, I noti…
Tag: solid-state-drive
Why io_submit(…, nr, …) might submit less requests than nr?
I’m using io_submit(…, nr, …) with nr up to 128 but I usually get fewer requests submitted. According to the manual IO_SUBMIT(2), this is legit but I wonder: why? Also, is there a way to know which request was submitted right away – without checking io_getevents()? From the manual: On …
Decrease in Random read IOPs on NVME SSD if requests issued over small region
(TL;DR) On NVME SSDs (Intel p3600 as well as Avant), I am seeing decrease in the IOPS if I issue random reads over a small subset of the disk instead of the entire disk. While reading the same offset over and over, the IOPS are about 36-40K for 4k blocksize. The IOPS gradually increase as I grow the region ov…
Optimal way of writing to append-only files on an SSD
I want to know what’s the optimal way to log to an SSD. Think of something like a database log, where you’re writing append-only, but you also have to fsync() every transaction or few transactions to ensure application level data durability. I’m going to give some background on how SSDs work…