Messages in this thread | | | Date | Thu, 29 May 2014 13:05:44 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] vmalloc: use rcu list iterator to reduce vmap_area_lock contention |
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On Thu, 29 May 2014 15:22:34 +0900 Joonsoo Kim <iamjoonsoo.kim@lge.com> wrote:
> Richard Yao reported a month ago that his system have a trouble > with vmap_area_lock contention during performance analysis > by /proc/meminfo. Andrew asked why his analysis checks /proc/meminfo > stressfully, but he didn't answer it. > > https://lkml.org/lkml/2014/4/10/416 > > Although I'm not sure that this is right usage or not, there is a solution > reducing vmap_area_lock contention with no side-effect. That is just > to use rcu list iterator in get_vmalloc_info(). This function only needs > values on vmap_area structure, so we don't need to grab a spinlock.
The mixture of rcu protection and spinlock protection for vmap_area_list is pretty confusing. Are you able to describe the overall design here? When and why do we use one versus the other?
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