Re: softirq considered harmful

Andrew Morton
2006-08-12T23:29:03Z

On Thu, 10 Aug 2006 13:06:27 +0200
Jens Axboe <axboe@suse.de> wrote:

> Ok maybe that is a little too strong, but I am indeed seeing some very
> sucky behaviour with softirqs here. The block layer uses it for doing
> request completions

I wasn't even aware that this change had been made. I don't recall (and I
cannot locate) any mailing list discussion of it.

Maybe I missed the discussion. But if not, this is yet another case of
significant changes getting into mainline via a git merge and sneaking
under everyone's radar.

It seems like a bad idea to me. Any additional latency at all in disk
completion adds directly onto process waiting time - we do a _lot_ of
synchronous disk IO.

There is no mention in the changelog of any observed problems which this
patch solves. Can we revert it please?