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SubjectRe: [PATCH] fs/proc: add VmTaskSize field to /proc/$$/status
On Thu, Apr 25, 2019 at 04:57:47PM -0400, Joel Savitz 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.
>
> Signed-off-by: Joel Savitz <jsavitz@redhat.com>
> ---
> fs/proc/task_mmu.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 92a91e7816d8..f64b9a949624 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -74,7 +74,10 @@ void task_mem(struct seq_file *m, struct mm_struct *mm)
> seq_put_decimal_ull_width(m,
> " kB\nVmPTE:\t", mm_pgtables_bytes(mm) >> 10, 8);
> SEQ_PUT_DEC(" kB\nVmSwap:\t", swap);
> - seq_puts(m, " kB\n");
> + SEQ_PUT_DEC(" kB\nVmSwap:\t", swap);
> + seq_put_decimal_ull_width(m,
> + " kB\nVmTaskSize:\t", TASK_SIZE >> 10, 8);
> + seq_puts(m, " kB\n");
> hugetlb_report_usage(m, mm);
> }
> #undef SEQ_PUT_DEC
> --
> 2.18.1
>
Acked-by: Rafael Aquini <aquini@redhat.com>

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