Re: [PATCH] Don't apply for write lock on tasklist_lock if parentdoesn't ptrace other processes

[Oleg Nesterov]

On 07/23, Zhang, Yanmin wrote:
>
> On Thu, 2010-07-22 at 11:05 +0200, Oleg Nesterov wrote:
> > I am not surpized perf blaims tasklist, but I am really surpized this patch
> > adds 10% improvement...
> I changed aim7 workfile to focus on fork/exec and other a couple of sub-cases.
> And this behavior is clear on 8-socket machines. 

Thanks...

> After applying my patch (although it's incorrect as there is a race with TRACEME),
> perf shows write_lock_irq in forget_original_parent consumes less than 40% cpu time on
> 8-socket machine.

Any chance you can test the patch I sent? It should have the same effect,
otherwise there is something interesting.

> Is it possible to optimize it to use finer locks instead of the global tasklist_lock?

Heh. We must optimize it. But it is not clear when ;)

Oleg.

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