您可以尝试使用 fadvice 和 madvice，但不能保证。两者都更可能适用于更大的文件/数据，因为：
部分页面是故意保留的，因为期望保留需要的内存比丢弃不需要的内存要好。
查看 linux 源代码，什么会做什么，什么不会。例如 POSIX_FADV_NOREUSE 不做任何事情。
http://lxr.free-electrons.com/source/mm/fadvise.c#L62
http://lxr.free-electrons.com/source/mm/madvise.c
package main
import "fmt"
import "os"
import "syscall"
import "golang.org/x/sys/unix"
func main() {
advise := false
if len(os.Args) > 1 && os.Args[1] == "-x" {
fmt.Println("setting file advise")
advise =true
}
data := make([]byte, 100)
handler, err := os.Open("Foo.txt")
if err != nil {
fmt.Println("Failed on open: ", err)
}; defer handler.Close()
if advise {
unix.Fadvise(int(handler.Fd()), 0, 0, 4) // 4 == POSIX_FADV_DONTNEED
}
read, err := handler.Read(data)
if err != nil {
fmt.Println("Failed on read: ", err)
os.Exit(1)
}
if advise {
syscall.Madvise(data, 4) // 4 == MADV_DONTNEED
}
fmt.Printf("read %v bytes\n", read)
}
/usr/bin/time -v ./direct -x
Command being timed: "./direct -x"
User time (seconds): 0.00
System time (seconds): 0.00
Percent of CPU this job got: 0%
Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.03
Average shared text size (kbytes): 0
Average unshared data size (kbytes): 0
Average stack size (kbytes): 0
Average total size (kbytes): 0
Maximum resident set size (kbytes): 1832
Average resident set size (kbytes): 0
Major (requiring I/O) page faults: 2
Minor (reclaiming a frame) page faults: 149
Voluntary context switches: 2
Involuntary context switches: 2
Swaps: 0
File system inputs: 200
File system outputs: 0
Socket messages sent: 0
Socket messages received: 0
Signals delivered: 0
Page size (bytes): 4096
Exit status: 0