Re: [PATCH] fs/proc: add VmTaskSize field to /proc/$$/status

[Andrew Morton]

On Thu, 25 Apr 2019 16:57:47 -0400 Joel Savitz <jsavitz@xxxxxxxxxx> wrote:

> Currently, there is no fast mechanism to get the virtual memory size of
> the current process from userspace. This information is available to the
> user through several means, one being a linear search of the entire address
> space. This is the method used by a component of the libhugetlb kernel
> test, and using the mechanism proposed in this patch, the time complexity
> of that test would be upgraded to constant time from linear time. This is
> especially relevant on 64-bit architechtures where a linear search of
> the address space could take an absurd amount of time. Using this
> mechanism, the modification to the test component would be portable
> across all architechtures.

Please include all details on the observed performance improvements.

>  fs/proc/task_mmu.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)

Please update Documentation/filesystems/proc.txt.