On Mon, May 06, 2019 at 11:53:43AM -0400, Joel Savitz wrote:
> There is currently no easy and architecture-independent way to find the
> lowest unusable virtual address available to a process without
> brute-force calculation. This patch allows a user to easily retrieve
> this value via /proc/<pid>/status.
>
> Using this patch, any program that previously needed to waste cpu cycles
> recalculating a non-sensitive process-dependent value already known to
> the kernel can now be optimized to use this mechanism.
>
> Signed-off-by: Joel Savitz <jsav...@redhat.com>
> ---
> Documentation/filesystems/proc.txt | 2 ++
> fs/proc/task_mmu.c | 2 ++
> 2 files changed, 4 insertions(+)
>
> diff --git a/Documentation/filesystems/proc.txt
> b/Documentation/filesystems/proc.txt
> index 66cad5c86171..1c6a912e3975 100644
> --- a/Documentation/filesystems/proc.txt
> +++ b/Documentation/filesystems/proc.txt
> @@ -187,6 +187,7 @@ read the file /proc/PID/status:
> VmLib: 1412 kB
> VmPTE: 20 kb
> VmSwap: 0 kB
> + VmTaskSize: 137438953468 kB
> HugetlbPages: 0 kB
> CoreDumping: 0
> THP_enabled: 1
> @@ -263,6 +264,7 @@ Table 1-2: Contents of the status files (as of 4.19)
> VmPTE size of page table entries
> VmSwap amount of swap used by anonymous private data
> (shmem swap usage is not included)
> + VmTaskSize lowest unusable address in process virtual
> memory
Can we change this help text to "size of process' virtual address space memory"
?
> HugetlbPages size of hugetlb memory portions
> CoreDumping process's memory is currently being dumped
> (killing the process may lead to a corrupted
> core)
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 95ca1fe7283c..0af7081f7b19 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -74,6 +74,8 @@ 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_put_decimal_ull_width(m,
> + " kB\nVmTaskSize:\t", mm->task_size >> 10, 8);
> seq_puts(m, " kB\n");
> hugetlb_report_usage(m, mm);
> }
> --
> 2.18.1
>
Acked-by: Rafael Aquini <aqu...@redhat.com>
