+ CC folks who focus on reclaim
On 3/4/20 9:32 PM, Adam Jackson wrote:
> The page reclamation scanner tries to keep executable pages resident,
> since taking a hard page fault to satisfy an icache miss is really not
> great for interactivity. Anonymous executable pages tend to contain
> code that has been just-in-time compiled for performance reasons. By
> requiring that executable pages be file-backed, we're putting possibly
> the most performance-sensitive code at higher risk of eviction, which
> seems backwards.
>
> On an amd64 machine running Fedora 31, the firefox I happen to have
> running requires about 89M of file-backed text and 12M of anonymous text
> for 30 open tabs. The next largest process in terms of anonymous text is
> gnome-shell, with 1M anonymous and 57M file-backed. No other process had
> significant anonymous text, most had none. Penalizing those 13M
> specifically when under memory pressure seems like an easy hazard to
> avoid.
>
> Signed-off-by: Adam Jackson <ajax@xxxxxxxxxx>
> ---
> mm/vmscan.c | 11 ++++-------
> 1 file changed, 4 insertions(+), 7 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index ee4eecc7e1c2..9bfbc30d61d8 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2095,15 +2095,12 @@ static void shrink_active_list(unsigned long nr_to_scan,
> &vm_flags)) {
> nr_rotated += hpage_nr_pages(page);
> /*
> - * Identify referenced, file-backed active pages and
> - * give them one more trip around the active list. So
> + * Identify referenced, executable active pages and
> + * give them one more trip around the active list, so
> * that executable code get better chances to stay in
> - * memory under moderate memory pressure. Anon pages
> - * are not likely to be evicted by use-once streaming
> - * IO, plus JVM can create lots of anon VM_EXEC pages,
> - * so we ignore them here.
> + * memory under moderate memory pressure.
> */
> - if ((vm_flags & VM_EXEC) && page_is_file_cache(page)) {
> + if ((vm_flags & VM_EXEC)) {
> list_add(&page->lru, &l_active);
> continue;
> }
>
