[Devel] [PATCH RH8] kstat: Make kstat_glob::swap_in percpu

[Andrey Zhadchenko]

From: Kirill Tkhai <ktkhai at virtuozzo.com>

Patchset description:
Make kstat_glob::swap_in percpu and cleanup

This patchset continues escaping of kstat_glb_lock
and makes swap_in percpu. Also, newly unused primitives
are dropped and reduced memory usage by using percpu
seqcount (instead of separate percpu seqcount for every
kstat percpu variable).

Kirill Tkhai (4):
      kstat: Make kstat_glob::swap_in percpu
      kstat: Drop global kstat_lat_struct
      kstat: Drop cpu argument in KSTAT_LAT_PCPU_ADD()
      kstat: Make global percpu kstat_pcpu_seq instead of percpu seq for every
             variable

==========================================
This patch description:

Using of global local is not good for scalability.
Better we make swap_in percpu, and it will be updated
lockless like other statistics (e.g., page_in).

Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>

Ported to vz8:
 - Dropped all patchset but this patch, since it is already partially included
 - Introduced start in do_swap_page to use it for kstat_glob.swap_in

(cherry picked from ed033a381e01996f7f8061d9838d1c9ec6b38d96)
Signed-off-by: Andrey Zhadchenko <andrey.zhadchenko at virtuozzo.com>
---
 mm/memory.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/mm/memory.c b/mm/memory.c
index b64f317..3a48379 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3037,7 +3037,9 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 	int locked;
 	int exclusive = 0;
 	vm_fault_t ret = 0;
+	cycles_t start;
 
+	start = get_cycles();
 	if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
 		goto out;
 
@@ -3226,6 +3228,10 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 unlock:
 	pte_unmap_unlock(vmf->pte, vmf->ptl);
 out:
+	local_irq_disable();
+	KSTAT_LAT_PCPU_ADD(&kstat_glob.swap_in, get_cycles() - start);
+	local_irq_enable();
+
 	return ret;
 out_nomap:
 	mem_cgroup_cancel_charge(page, memcg, false);
-- 
1.8.3.1