On Tue, Nov 3, 2026 at 10:58 AM Ridong Chen <[email protected]> wrote:
>
> From: Ridong Chen <[email protected]>
>
> Aging in MGLRU advances max_seq via inc_max_seq(), creating a new
> youngest generation. There is currently no tracepoint on this path, so
> the moment a new generation is created, and how the min_seq of each type
> trails behind it, cannot be observed as it happens.
We might be more interested in why aging is triggered rather
than the exact moment when max_seq is advanced.
With your patch, we get:
~ # cat /sys/kernel/tracing/trace | grep mglru_inc_max_seq
a.out-93 [001] d..1. 278.276539:
mm_mglru_inc_max_seq: nid=0 memcg_id=1 max_seq=4 anon_min_seq=2
file_min_seq=1 nr_anon={0x0,0xf016,0x12,0x0}
nr_file={0x1886,0xb,0x4c,0x0}
kswapd0-50 [000] d..1. 278.422400:
mm_mglru_inc_max_seq: nid=0 memcg_id=1 max_seq=5 anon_min_seq=2
file_min_seq=2 nr_anon={0x5,0xccb6,0x3439,0x0}
nr_file={0x4ae,0x4f,0x55,0x0}
kswapd0-50 [000] d..1. 278.508003:
mm_mglru_inc_max_seq: nid=0 memcg_id=1 max_seq=6 anon_min_seq=3
file_min_seq=4 nr_anon={0xccb6,0x3d29,0x1,0x0}
nr_file={0x0,0x59,0x7,0x0}
kswapd0-50 [000] d..1. 280.046056:
mm_mglru_inc_max_seq: nid=0 memcg_id=1 max_seq=7 anon_min_seq=4
file_min_seq=5 nr_anon={0x3bf3,0xcbbd,0x23e,0x0}
nr_file={0x0,0xb,0x1,0x0}
kswapd0-50 [000] d..1. 280.124876:
mm_mglru_inc_max_seq: nid=0 memcg_id=1 max_seq=8 anon_min_seq=5
file_min_seq=6 nr_anon={0xcafd,0x3e31,0x0,0x0}
nr_file={0x0,0x5,0x7,0x0}
a.out-96 [001] d..1. 290.629014:
mm_mglru_inc_max_seq: nid=0 memcg_id=1 max_seq=9 anon_min_seq=7
file_min_seq=6 nr_anon={0x0,0x10615,0xb,0x0}
nr_file={0x331,0xb,0x9a,0x0}
kswapd0-50 [000] d..1. 290.653098:
mm_mglru_inc_max_seq: nid=0 memcg_id=1 max_seq=10 anon_min_seq=7
file_min_seq=7 nr_anon={0x15,0xef23,0x18c4,0x0}
nr_file={0xb,0xb8,0x55,0x0}
a.out-96 [001] d..1. 290.684875:
mm_mglru_inc_max_seq: nid=0 memcg_id=1 max_seq=11 anon_min_seq=8
file_min_seq=9 nr_anon={0xeee3,0x1afb,0x2,0x0}
nr_file={0x0,0x76,0x4,0x0}
You can see that the youngest generation is always zero,
because you're just getting the newly added youngest
generation :-)
This somehow suggests that the information is redundant, as
there is always a zero there.
I suspect we'll need an additional tracepoint to show why
aging is triggered and at what sc->priority it happens.
But do you know why you trace the moment just after aging
is completed, rather than the reason why aging is needed?
Best,
Regards
