Re: [PATCH 0/3] readfile(2): a new syscall to make open/read/close faster

On Sat, Jul 04, 2020 at 08:30:40PM +0100, Al Viro wrote:

On Sat, Jul 04, 2020 at 04:02:46PM +0200, Greg Kroah-Hartman wrote:

quoted

Here is a tiny new syscall, readfile, that makes it simpler to read
small/medium sized files all in one shot, no need to do open/read/close.
This is especially helpful for tools that poke around in procfs or
sysfs, making a little bit of a less system load than before, especially
as syscall overheads go up over time due to various CPU bugs being
addressed.

Nice series, but you are 3 months late with it...  Next AFD, perhaps?

Perhaps :)

Seriously, the rationale is bollocks.  If the overhead of 2 extra
syscalls is anywhere near the costs of the real work being done by
that thing, we have already lost and the best thing to do is to
throw the system away and start with saner hardware.

The real-work the kernel does is almost neglegant compared to the
open/close overhead of the syscalls on some platforms today.  I'll post
benchmarks with the next version of this patch series to hopefully show
that.  If not, then yeah, this isn't worth it, but it was fun to write.

thanks,

greg k-h