[Ksummit-discuss] [CORE TOPIC] Kernel tinification: shrinking the kernel and avoiding size regressions

[Michael Kerrisk (man-pages)]

On 05/02/2014 09:33 PM, Theodore Ts'o wrote:
> There's been a huge focus on system calls in this discussion, and I
> suspect this is a bit of a red herring.  Taking a look at "git log
> arch/x86/syscalls/syscall_64.tbl" --- since all the world's is no
> longer a Vax, but rather an x86_64 :-P --- there really hasn't been
> that many new system calls lately.  Yes, we recently added
> renameat(2), but the next addition was half a year earlier, when the
> new schedular parameters syscalls went in.

A minor correction: that wasn't 6 months ago -- it was 3.14, released 
at the end of March, that added sched_getattr() and sched_setattr().

> There's much more in the way of kernel functionality and complexity
> which isn't really syscall related --- for example, all of the control
> group stuff, and security hair caused by things like user namespaces,
> and new fallocate(2) modes --- we've added PUNCH_HOLE, COLLAPSE_RANGE,
> and ZERO_RANGE, and there are threats to add INSERT_RANGE in the next
> release or two.

Yes, that's a much bigger part of the growing surface. (Just by the 
bye, I try to track the growth of the surface at 
http://man7.org/tlpi/api_changes/ . Corrections and additions are 
welcome. It's reasonably complete with respect to system calls, 
partially complete on /proc and socket options, and rather out to 
lunch on other pieces such as /sys and other pseudo filesystems

Cheers,

Michael


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/