Re: workqueue thing

Tejun Heo
2009-12-23T08:33:07Z

Hello, Ingo.

On 12/23/2009 05:12 PM, Ingo Molnar wrote:
>
> * 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(-)

BTW, the code contains way more comment afterwards and has other
benefits like not having crazy number of workers around on many core
machines.

>> and you say it _wont_ help performance/scalability (this aspect wasnt clear

And I think it will help scalability for sure although it depends on
what type of scalability you're talking about.

>> 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

I'm not sure I'm gonna update that many places in a single sweep but
yeah let's give it a shot.

Thanks.

--
tejun