Re: [RFC PATCH RESEND 20/28] mm: introduce per-VMA lock statistics

[Suren Baghdasaryan <surenb@google.com>]

On Fri, Sep 9, 2022 at 7:29 AM Laurent Dufour <ldufour@linux.ibm.com> wrote:
>
> Le 01/09/2022 à 19:35, Suren Baghdasaryan a écrit :
> > Add a new CONFIG_PER_VMA_LOCK_STATS config option to dump extra
> > statistics about handling page fault under VMA lock.
> >
>
> Why not making this a default when per VMA lock are enabled?

Good idea. If no objections I'll make that change.

>
> > Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> > ---
> >  include/linux/vm_event_item.h | 6 ++++++
> >  include/linux/vmstat.h        | 6 ++++++
> >  mm/Kconfig.debug              | 8 ++++++++
> >  mm/vmstat.c                   | 6 ++++++
> >  4 files changed, 26 insertions(+)
> >
> > diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
> > index f3fc36cd2276..a325783ed05d 100644
> > --- a/include/linux/vm_event_item.h
> > +++ b/include/linux/vm_event_item.h
> > @@ -150,6 +150,12 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
> >  #ifdef CONFIG_X86
> >               DIRECT_MAP_LEVEL2_SPLIT,
> >               DIRECT_MAP_LEVEL3_SPLIT,
> > +#endif
> > +#ifdef CONFIG_PER_VMA_LOCK_STATS
> > +             VMA_LOCK_SUCCESS,
> > +             VMA_LOCK_ABORT,
> > +             VMA_LOCK_RETRY,
> > +             VMA_LOCK_MISS,
> >  #endif
> >               NR_VM_EVENT_ITEMS
> >  };
> > diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
> > index bfe38869498d..0c2611899cfc 100644
> > --- a/include/linux/vmstat.h
> > +++ b/include/linux/vmstat.h
> > @@ -131,6 +131,12 @@ static inline void vm_events_fold_cpu(int cpu)
> >  #define count_vm_vmacache_event(x) do {} while (0)
> >  #endif
> >
> > +#ifdef CONFIG_PER_VMA_LOCK_STATS
> > +#define count_vm_vma_lock_event(x) count_vm_event(x)
> > +#else
> > +#define count_vm_vma_lock_event(x) do {} while (0)
> > +#endif
> > +
> >  #define __count_zid_vm_events(item, zid, delta) \
> >       __count_vm_events(item##_NORMAL - ZONE_NORMAL + zid, delta)
> >
> > diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
> > index ce8dded36de9..075642763a03 100644
> > --- a/mm/Kconfig.debug
> > +++ b/mm/Kconfig.debug
> > @@ -207,3 +207,11 @@ config PTDUMP_DEBUGFS
> >         kernel.
> >
> >         If in doubt, say N.
> > +
> > +
> > +config PER_VMA_LOCK_STATS
> > +     bool "Statistics for per-vma locks"
> > +     depends on PER_VMA_LOCK
> > +     help
> > +       Statistics for per-vma locks.
> > +       If in doubt, say N.
> > diff --git a/mm/vmstat.c b/mm/vmstat.c
> > index 90af9a8572f5..3f3804c846a6 100644
> > --- a/mm/vmstat.c
> > +++ b/mm/vmstat.c
> > @@ -1411,6 +1411,12 @@ const char * const vmstat_text[] = {
> >       "direct_map_level2_splits",
> >       "direct_map_level3_splits",
> >  #endif
> > +#ifdef CONFIG_PER_VMA_LOCK_STATS
> > +     "vma_lock_success",
> > +     "vma_lock_abort",
> > +     "vma_lock_retry",
> > +     "vma_lock_miss",
> > +#endif
> >  #endif /* CONFIG_VM_EVENT_COUNTERS || CONFIG_MEMCG */
> >  };
> >  #endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA || CONFIG_MEMCG */
>