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[PATCH 0/3] mm/vmalloc: Cache the /proc/meminfo vmalloc statistics

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  [PATCH 0/3] mm/vmalloc: Cache the /proc/meminfo vmalloc statistics Ingo Molnar <mingo@kernel.org> - 2015-08-22 12:50 +0200
    Re: [PATCH 0/3] mm/vmalloc: Cache the /proc/meminfo vmalloc statistics Linus Torvalds <torvalds@linux-foundation.org> - 2015-08-22 16:40 +0200

#1211444 — [PATCH 0/3] mm/vmalloc: Cache the /proc/meminfo vmalloc statistics

This series is a variant of Linus's jiffies based caching approach in the:

   "get_vmalloc_info() and /proc/meminfo insanely expensive"

thread on lkml.

The idea is to track modifications to the vmalloc list by wrapping the
lock/unlock primitives, and to put a flag next to the spinlock. If the
spinlock is taken then it's cheap to modify this flag, and if it has
not been taken (the cached case) it will be a read-mostly variable
for every CPU in essence.

It seems to work for me, but it's only very (very!) lightly tested.

Would something like this be acceptable (and is it correct)?

Thanks,

    Ingo

Ingo Molnar (3):
  mm/vmalloc: Abstract out vmap_area_lock lock/unlock operations
  mm/vmalloc: Track vmalloc info changes
  mm/vmalloc: Cache the vmalloc memory info

 mm/vmalloc.c | 82 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 57 insertions(+), 25 deletions(-)

-- 
2.1.4

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#1211476

On Sat, Aug 22, 2015 at 3:44 AM, Ingo Molnar <mingo@kernel.org> wrote:
>
> Would something like this be acceptable (and is it correct)?

I don't think any of this can be called "correct", in that the
unlocked accesses to the cached state are clearly racy, but I think
it's very much "acceptable".

                   Linus
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