2020-06-15 22:21:38

by Peter Xu

Subject: [PATCH 13/25] mm/nds32: Use mm_fault_accounting()

Use the new mm_fault_accounting() helper for page fault accounting.

Avoid doing page fault accounting multiple times if the page fault is retried.
Since at it, move the accounting after releasing mmap_sem.

CC: Nick Hu <[email protected]>
CC: Greentime Hu <[email protected]>
CC: Vincent Chen <[email protected]>
Signed-off-by: Peter Xu <[email protected]>
---
arch/nds32/mm/fault.c | 19 +++----------------
1 file changed, 3 insertions(+), 16 deletions(-)

diff --git a/arch/nds32/mm/fault.c b/arch/nds32/mm/fault.c
index f331e533edc2..11537c03ab1d 100644
--- a/arch/nds32/mm/fault.c
+++ b/arch/nds32/mm/fault.c
@@ -78,7 +78,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
struct mm_struct *mm;
struct vm_area_struct *vma;
int si_code;
- vm_fault_t fault;
+ vm_fault_t fault, major = 0;
unsigned int mask = VM_ACCESS_FLAGS;
unsigned int flags = FAULT_FLAG_DEFAULT;

@@ -208,6 +208,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
*/

fault = handle_mm_fault(vma, addr, flags);
+ major |= fault & VM_FAULT_MAJOR;

/*
* If we need to retry but a fatal signal is pending, handle the
@@ -229,22 +230,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
goto bad_area;
}

- /*
- * Major/minor page fault accounting is only done on the initial
- * attempt. If we go through a retry, it is extremely likely that the
- * page will be found in page cache at that point.
- */
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
if (flags & FAULT_FLAG_ALLOW_RETRY) {
- if (fault & VM_FAULT_MAJOR) {
- tsk->maj_flt++;
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
- 1, regs, addr);
- } else {
- tsk->min_flt++;
- perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
- 1, regs, addr);
- }
if (fault & VM_FAULT_RETRY) {
flags |= FAULT_FLAG_TRIED;

@@ -257,6 +243,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
}

up_read(&mm->mmap_sem);
+ mm_fault_accounting(tsk, regs, addr, major);
return;

/*
--
2.26.2

2020-06-17 01:08:02

by Greentime Hu

Subject: Re: [PATCH 13/25] mm/nds32: Use mm_fault_accounting()

Peter Xu <[email protected]> 於 2020年6月16日 週二 上午6:16寫道：
>
> Use the new mm_fault_accounting() helper for page fault accounting.
>
> Avoid doing page fault accounting multiple times if the page fault is retried.
> Since at it, move the accounting after releasing mmap_sem.
>
> CC: Nick Hu <[email protected]>
> CC: Greentime Hu <[email protected]>
> CC: Vincent Chen <[email protected]>
> Signed-off-by: Peter Xu <[email protected]>
> ---
> arch/nds32/mm/fault.c | 19 +++----------------
> 1 file changed, 3 insertions(+), 16 deletions(-)
>
> diff --git a/arch/nds32/mm/fault.c b/arch/nds32/mm/fault.c
> index f331e533edc2..11537c03ab1d 100644
> --- a/arch/nds32/mm/fault.c
> +++ b/arch/nds32/mm/fault.c
> @@ -78,7 +78,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
> struct mm_struct *mm;
> struct vm_area_struct *vma;
> int si_code;
> - vm_fault_t fault;
> + vm_fault_t fault, major = 0;
> unsigned int mask = VM_ACCESS_FLAGS;
> unsigned int flags = FAULT_FLAG_DEFAULT;
>
> @@ -208,6 +208,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
> */
>
> fault = handle_mm_fault(vma, addr, flags);
> + major |= fault & VM_FAULT_MAJOR;
>
> /*
> * If we need to retry but a fatal signal is pending, handle the
> @@ -229,22 +230,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
> goto bad_area;
> }
>
> - /*
> - * Major/minor page fault accounting is only done on the initial
> - * attempt. If we go through a retry, it is extremely likely that the
> - * page will be found in page cache at that point.
> - */
> - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
> if (flags & FAULT_FLAG_ALLOW_RETRY) {
> - if (fault & VM_FAULT_MAJOR) {
> - tsk->maj_flt++;
> - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
> - 1, regs, addr);
> - } else {
> - tsk->min_flt++;
> - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
> - 1, regs, addr);
> - }
> if (fault & VM_FAULT_RETRY) {
> flags |= FAULT_FLAG_TRIED;
>
> @@ -257,6 +243,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
> }
>
> up_read(&mm->mmap_sem);
> + mm_fault_accounting(tsk, regs, addr, major);
> return;
>
> /*
> --
Hi Peter,

Thank you. :)
Acked-by: Greentime Hu <[email protected]>