Messages in this thread | | | Date | Tue, 17 Sep 2013 10:56:42 +0800 | From | Fengguang Wu <> | Subject | Re: increased vmap_area_lock contentions on "n_tty: Move buffers into n_tty_data" |
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On Mon, Sep 16, 2013 at 10:42:11PM -0400, Peter Hurley wrote: > On 09/12/2013 11:38 PM, Fengguang Wu wrote: > >On Thu, Sep 12, 2013 at 08:17:00PM -0700, Greg KH wrote: > >>On Fri, Sep 13, 2013 at 08:51:33AM +0800, Fengguang Wu wrote: > >>>Hi Peter, > >>> > >>>FYI, we noticed much increased vmap_area_lock contentions since this > >>>commit: > >> > >>What does that mean? What is happening, are we allocating/removing more > >>memory now? > > > >// leave this question to Peter and Tejun. :) > > > >>What type of load were you running that showed this problem? > > > >The increased contentions and lock hold/wait time showed up in a > >number of test cases. > > How is the raw data acquired? > > For example, is the test apparatus reading from /proc/vmallocinfo > (which claims the vmap_area_lock) during the test execution?
We didn't read /proc/vmallocinfo and read /proc/lock_stat once when the test ends.
> I'm wondering if a Heisenberg effect is happening here.
Thanks, Fengguang
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