Message ID | 20231021144317.3400916-2-chengming.zhou@linux.dev (mailing list archive) |
---|---|
State | New |
Headers | show |
Series | slub: Delay freezing of CPU partial slabs | expand |
On Sat, Oct 21, 2023 at 02:43:12PM +0000, chengming.zhou@linux.dev wrote: > +++ b/include/linux/page-flags.h > @@ -478,6 +478,8 @@ PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD) > TESTCLEARFLAG(Active, active, PF_HEAD) > PAGEFLAG(Workingset, workingset, PF_HEAD) > TESTCLEARFLAG(Workingset, workingset, PF_HEAD) > + __SETPAGEFLAG(Workingset, workingset, PF_HEAD) > + __CLEARPAGEFLAG(Workingset, workingset, PF_HEAD) This makes me nervous. The __ versions can only be used when there are guaranteed to be no other accesses to the flags. It's never going to be the case that we want code to call __folio_set_workingset(). _Assuming_ that it's safe to use the non-atomic flag setting, I'd rather see this done as ... static inline void slab_set_node_partial(struct slab *slab) { __folio_set_workingset(slab_folio(slab)); __set_bit(PG_workingset, folio_flags(slab_folio(slab), 0)); }
On Mon, Oct 23, 2023 at 01:32:27PM +0100, Matthew Wilcox wrote: > _Assuming_ that it's safe to use the non-atomic flag setting, I'd > rather see this done as ... > > static inline void slab_set_node_partial(struct slab *slab) > { > __folio_set_workingset(slab_folio(slab)); Ugh, I meant to delete this line. I meant to just write the next line. > __set_bit(PG_workingset, folio_flags(slab_folio(slab), 0)); > }
On 2023/10/24 00:22, Matthew Wilcox wrote: > On Mon, Oct 23, 2023 at 01:32:27PM +0100, Matthew Wilcox wrote: >> _Assuming_ that it's safe to use the non-atomic flag setting, I'd >> rather see this done as ... >> >> static inline void slab_set_node_partial(struct slab *slab) >> { >> __folio_set_workingset(slab_folio(slab)); > > Ugh, I meant to delete this line. I meant to just write the next line. > >> __set_bit(PG_workingset, folio_flags(slab_folio(slab), 0)); >> } Yes, it's safe to use the non-atomic version here, since it's protected by the slub per-node list_lock and we want better performance here. Ok, will change to directly use __set_bit() and __clear_bit() instead of polluting the "workingset" interfaces there. Thanks.
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index a88e64acebfe..e8b1be71d722 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -478,6 +478,8 @@ PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD) TESTCLEARFLAG(Active, active, PF_HEAD) PAGEFLAG(Workingset, workingset, PF_HEAD) TESTCLEARFLAG(Workingset, workingset, PF_HEAD) + __SETPAGEFLAG(Workingset, workingset, PF_HEAD) + __CLEARPAGEFLAG(Workingset, workingset, PF_HEAD) __PAGEFLAG(Slab, slab, PF_NO_TAIL) PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */ diff --git a/mm/slab.h b/mm/slab.h index 8cd3294fedf5..9cff64cae8de 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -193,6 +193,25 @@ static inline void __slab_clear_pfmemalloc(struct slab *slab) __folio_clear_active(slab_folio(slab)); } +/* + * Slub reuse PG_workingset bit to keep track of whether it's on + * the per-node partial list. + */ +static inline bool slab_test_node_partial(const struct slab *slab) +{ + return folio_test_workingset((struct folio *)slab_folio(slab)); +} + +static inline void slab_set_node_partial(struct slab *slab) +{ + __folio_set_workingset(slab_folio(slab)); +} + +static inline void slab_clear_node_partial(struct slab *slab) +{ + __folio_clear_workingset(slab_folio(slab)); +} + static inline void *slab_address(const struct slab *slab) { return folio_address(slab_folio(slab)); diff --git a/mm/slub.c b/mm/slub.c index 63d281dfacdb..3fad4edca34b 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2127,6 +2127,7 @@ __add_partial(struct kmem_cache_node *n, struct slab *slab, int tail) list_add_tail(&slab->slab_list, &n->partial); else list_add(&slab->slab_list, &n->partial); + slab_set_node_partial(slab); } static inline void add_partial(struct kmem_cache_node *n, @@ -2141,6 +2142,7 @@ static inline void remove_partial(struct kmem_cache_node *n, { lockdep_assert_held(&n->list_lock); list_del(&slab->slab_list); + slab_clear_node_partial(slab); n->nr_partial--; } @@ -4831,6 +4833,7 @@ static int __kmem_cache_do_shrink(struct kmem_cache *s) if (free == slab->objects) { list_move(&slab->slab_list, &discard); + slab_clear_node_partial(slab); n->nr_partial--; dec_slabs_node(s, node, slab->objects); } else if (free <= SHRINK_PROMOTE_MAX)