Re: workqueue thing

Ingo Molnar
2009-12-23T08:14:36Z

* Ingo Molnar <mingo@elte.hu> wrote:

> At least as far as i'm concerned, i'd like to see actual uses. It's a big
> linecount increase all things considered:
>
> 20 files changed, 2783 insertions(+), 660 deletions(-)
>
> and you say it _wont_ help performance/scalability (this aspect wasnt clear
> to me from previous discussions), so the (yet to be seen) complexity
> reduction in other code ought to be worth it.

To further stress this point, i'd like to point to the very first commit that
introduced kernel/workqueue.c into Linux 7 years ago:

| From 6ed12ff83c765aeda7d38d3bf9df7d46d24bfb11 Mon Sep 17 00:00:00 2001
| From: Ingo Molnar <mingo@elte.hu>
| Date: Mon, 30 Sep 2002 22:17:42 -0700
| Subject: [PATCH] [PATCH] Workqueue Abstraction

look at the diffstat of that commit:

201 files changed, 1102 insertions(+), 1194 deletions(-)

despite adding a new abstraction and kernel subsystem (workqueues), that
commit modified more than a hundred drivers to make use of it, and managed to
achieve a net linecount decrease of 92 lines - despite adding hundreds of
lines of a new core facility.

Likewise, for this particular patchset it should be possible to identify
existing patterns of code in the existing code base of 6+ millions lines of
Linux driver code that would make the advantages of this +2000 lines of core
kernel code plain obvious. There were multipe claims of problems with the
current abstractions - so there sure must be a way to show off the new code in
a few places.

Ingo