Re: [PATCH v3 3/3] mm, memcg: inline swap-related functions to improve disabled memcg config
From: Michal Hocko <hidden>
Date: 2021-07-12 07:51:17
Also in:
linux-mm, lkml
On Fri 09-07-21 17:36:26, Suren Baghdasaryan wrote:
Inline mem_cgroup_try_charge_swap, mem_cgroup_uncharge_swap and
cgroup_throttle_swaprate functions to perform mem_cgroup_disabled static
key check inline before calling the main body of the function. This
minimizes the memcg overhead in the pagefault and exit_mmap paths when
memcgs are disabled using cgroup_disable=memory command-line option.
This change results in ~1% overhead reduction when running PFT test
comparing {CONFIG_MEMCG=n} against {CONFIG_MEMCG=y, cgroup_disable=memory}
configuration on an 8-core ARM64 Android device.
Signed-off-by: Suren Baghdasaryan <redacted>
Reviewed-by: Shakeel Butt <redacted>
Acked-by: Johannes Weiner <redacted>I find it a bit surprising to see such a big difference over a function call in a slow path like swap in/out. Anyway the change makes sense. Acked-by: Michal Hocko <mhocko-IBi9RG/b67k@public.gmane.org> Thanks!
quoted hunk ↗ jump to hunk
--- include/linux/swap.h | 26 +++++++++++++++++++++++--- mm/memcontrol.c | 14 ++++---------- mm/swapfile.c | 5 +---- 3 files changed, 28 insertions(+), 17 deletions(-)diff --git a/include/linux/swap.h b/include/linux/swap.h index 6f5a43251593..f30d26b0f71d 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h@@ -721,7 +721,13 @@ static inline int mem_cgroup_swappiness(struct mem_cgroup *mem) #endif #if defined(CONFIG_SWAP) && defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP) -extern void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask); +extern void __cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask); +static inline void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask) +{ + if (mem_cgroup_disabled()) + return; + __cgroup_throttle_swaprate(page, gfp_mask); +} #else static inline void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask) {@@ -730,8 +736,22 @@ static inline void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask) #ifdef CONFIG_MEMCG_SWAP extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry); -extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry); -extern void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages); +extern int __mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry); +static inline int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) +{ + if (mem_cgroup_disabled()) + return 0; + return __mem_cgroup_try_charge_swap(page, entry); +} + +extern void __mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages); +static inline void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages) +{ + if (mem_cgroup_disabled()) + return; + __mem_cgroup_uncharge_swap(entry, nr_pages); +} + extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg); extern bool mem_cgroup_swap_full(struct page *page); #elsediff --git a/mm/memcontrol.c b/mm/memcontrol.c index cdaf7003b43d..0b05322836ec 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c@@ -7234,7 +7234,7 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) } /** - * mem_cgroup_try_charge_swap - try charging swap space for a page + * __mem_cgroup_try_charge_swap - try charging swap space for a page * @page: page being added to swap * @entry: swap entry to charge *@@ -7242,16 +7242,13 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) * * Returns 0 on success, -ENOMEM on failure. */ -int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) +int __mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) { unsigned int nr_pages = thp_nr_pages(page); struct page_counter *counter; struct mem_cgroup *memcg; unsigned short oldid; - if (mem_cgroup_disabled()) - return 0; - if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) return 0;@@ -7287,18 +7284,15 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) } /** - * mem_cgroup_uncharge_swap - uncharge swap space + * __mem_cgroup_uncharge_swap - uncharge swap space * @entry: swap entry to uncharge * @nr_pages: the amount of swap space to uncharge */ -void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages) +void __mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages) { struct mem_cgroup *memcg; unsigned short id; - if (mem_cgroup_disabled()) - return; - id = swap_cgroup_record(entry, 0, nr_pages); rcu_read_lock(); memcg = mem_cgroup_from_id(id);diff --git a/mm/swapfile.c b/mm/swapfile.c index 707fa0481bb4..04a0c83f1313 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c@@ -3773,14 +3773,11 @@ static void free_swap_count_continuations(struct swap_info_struct *si) } #if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP) -void cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask) +void __cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask) { struct swap_info_struct *si, *next; int nid = page_to_nid(page); - if (mem_cgroup_disabled()) - return; - if (!(gfp_mask & __GFP_IO)) return;-- 2.32.0.93.g670b81a890-goog
-- Michal Hocko SUSE Labs