Will the speed really be the same if you add 1MB and 1GB files?

Exploring the difference in appending write speed between large and small files

Programmers often use the append function to append data to files. A common question is: Is the speed of appending to write 1MB files and 1GB files the same?

Let's assume that we append the string "hello world" to the 1MB and 1GB log files, respectively. Intuitively, it takes longer to process large files. But the reality is not that simple.

The conclusion is that append write efficiency is not significantly affected by file size. The operating system uses a file pointer to point to the end of the file, and append writes directly to this location without additional addressing or data movement. Therefore, writing "hello world" to 1MB or 1GB files has very little time difference.

However, in practical applications, writing speeds of oversized files (such as 10GB) may become slower. This is not a problem with the efficiency of the append operation itself, but the result of the combined effect of factors such as disk I/O speed, memory cache, and operating system scheduling. Extremely large files can cause frequent disk access, which can slow down write speed. This has nothing to do with the append write mechanism, but is a limitation of the file system and hardware resources.

Therefore, the speed of writing small files and large files in the append operation itself is basically the same, but the actual writing speed is indirectly affected by the system I/O performance and resource management.

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