On Mon, 29 Aug 2022 11:50:29 +0000 "Zhou, YidingX" <yidingx.z...@intel.com> wrote:
> I draw a diagram to describe it more clearly > > fwrite fclose/fflush > fclose/fdatasync > --------->| libc buffer |----------------> | disk cache in RAM > |---------------------> |disk| > | 4096 Bytes | | size is determined by > OS | | | > > When the libc buffer is full, the system will automatically sync it to the > disk cache. > It is easily full as it's only 4096 B size. so there is no need to call > 'fflush()' every time. > The real time consuming action is syncing the disk cache to disk. > Because the disk cache is very large, it will take a long time to sync all at > one time during 'fclose()', > so need to call 'fdatasync()' periodically to amortize the time. If you want to speed up this, then get rid of stdio and use a faster API like io_uring. What you tried can help but using a better API would make bigger gains.
