Re: [patch]block: fix ioc locking warning

From: Jens Axboe
Date: Mon Feb 06 2012 - 15:16:13 EST

On 2012-02-06 18:27, Tejun Heo wrote:
> Hello,
> On Mon, Feb 06, 2012 at 08:58:49AM -0800, Linus Torvalds wrote:
>> On Mon, Feb 6, 2012 at 8:44 AM, Tejun Heo <tj@xxxxxxxxxx> wrote:
>>> Yeah, this seems better to me. Jens, if you're gonna amend the
>>> commit, please consider collapsing the following patch into the
>>> original patch too. Thanks.
>> Guys, is it *really* worth it to do all these crazy games?
>> How bad is it to just always use the async freeing, instead of this
>> clearly very fragile crazy direct-freeing-with-serious-locking-issues
>> thing?
> It's one wq scheduling on exit for any task which has issued an IO. I
> don't think it would matter except for task fork/exit microbenchs (or
> workloads which approximate to that). I'll get some measurements and
> strip the optimization if it doesn't really show up.

One (arguably stupid) thing that some users do do is something like:

$ find . -exec grep foo '{}' \;

So that would probably be a good pathological test case for this.

Jens Axboe

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