* Re: [PATCH 04/11] ARCv2: mm: THP support
[not found] ` <1440666194-21478-5-git-send-email-vgupta@synopsys.com>
@ 2015-08-27 15:32 ` Kirill A. Shutemov
2015-08-27 16:56 ` Vineet Gupta
0 siblings, 1 reply; 5+ messages in thread
From: Kirill A. Shutemov @ 2015-08-27 15:32 UTC (permalink / raw)
To: Vineet Gupta
Cc: Andrew Morton, Aneesh Kumar K.V, Kirill A. Shutemov, Mel Gorman,
Matthew Wilcox, Minchan Kim, linux-arch, linux-kernel, linux-mm,
arc-linux-dev
On Thu, Aug 27, 2015 at 02:33:07PM +0530, Vineet Gupta wrote:
> +pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
> +{
> + struct list_head *lh;
> + pgtable_t pgtable;
> + pte_t *ptep;
> +
> + assert_spin_locked(&mm->page_table_lock);
> +
> + pgtable = pmd_huge_pte(mm, pmdp);
> + lh = (struct list_head *) pgtable;
> + if (list_empty(lh))
> + pmd_huge_pte(mm, pmdp) = (pgtable_t) NULL;
> + else {
> + pmd_huge_pte(mm, pmdp) = (pgtable_t) lh->next;
> + list_del(lh);
> + }
Side question: why pgtable_t is unsigned long on ARC and not struct page *
or pte_t *, like on other archs? We could avoid these casts.
--
Kirill A. Shutemov
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 04/11] ARCv2: mm: THP support
2015-08-27 15:32 ` [PATCH 04/11] ARCv2: mm: THP support Kirill A. Shutemov
@ 2015-08-27 16:56 ` Vineet Gupta
0 siblings, 0 replies; 5+ messages in thread
From: Vineet Gupta @ 2015-08-27 16:56 UTC (permalink / raw)
To: Kirill A. Shutemov
Cc: Andrew Morton, Aneesh Kumar K.V, Kirill A. Shutemov, Mel Gorman,
Matthew Wilcox, Minchan Kim, linux-arch, linux-kernel, linux-mm,
arc-linux-dev
On Thursday 27 August 2015 09:02 PM, Kirill A. Shutemov wrote:
> On Thu, Aug 27, 2015 at 02:33:07PM +0530, Vineet Gupta wrote:
>> > +pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
>> > +{
>> > + struct list_head *lh;
>> > + pgtable_t pgtable;
>> > + pte_t *ptep;
>> > +
>> > + assert_spin_locked(&mm->page_table_lock);
>> > +
>> > + pgtable = pmd_huge_pte(mm, pmdp);
>> > + lh = (struct list_head *) pgtable;
>> > + if (list_empty(lh))
>> > + pmd_huge_pte(mm, pmdp) = (pgtable_t) NULL;
>> > + else {
>> > + pmd_huge_pte(mm, pmdp) = (pgtable_t) lh->next;
>> > + list_del(lh);
>> > + }
> Side question: why pgtable_t is unsigned long on ARC and not struct page *
> or pte_t *, like on other archs? We could avoid these casts.
This goes back how I did this for ARC long back to avoid page_address() calls in
general case. e.g. pte_alloc_one(), pmd_populate(), pte_free()... all needed to
convert struct page to unsigned long. It was micro-optimization of sorts, but
served us well.
I could perhaps see try making it pte *, that will certainly remove a bunch of
other casts as well.
-Vineet
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 08/11] mm,thp: reduce ifdef'ery for THP in generic code
[not found] ` <1440666194-21478-9-git-send-email-vgupta@synopsys.com>
@ 2015-09-16 22:25 ` Andrew Morton
0 siblings, 0 replies; 5+ messages in thread
From: Andrew Morton @ 2015-09-16 22:25 UTC (permalink / raw)
To: Vineet Gupta
Cc: Aneesh Kumar K.V, Kirill A. Shutemov, Mel Gorman, Matthew Wilcox,
Minchan Kim, linux-arch, linux-kernel, linux-mm, arc-linux-dev
On Thu, 27 Aug 2015 14:33:11 +0530 Vineet Gupta <Vineet.Gupta1@synopsys.com> wrote:
> This is purely cosmetic, just makes code more readable
>
> ...
>
> --- a/include/asm-generic/pgtable.h
> +++ b/include/asm-generic/pgtable.h
> @@ -30,9 +30,20 @@ extern int ptep_set_access_flags(struct vm_area_struct *vma,
> #endif
>
> #ifndef __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> extern int pmdp_set_access_flags(struct vm_area_struct *vma,
> unsigned long address, pmd_t *pmdp,
> pmd_t entry, int dirty);
> +#else /* CONFIG_TRANSPARENT_HUGEPAGE */
> +static inline int pmdp_set_access_flags(struct vm_area_struct *vma,
> + unsigned long address, pmd_t *pmdp,
> + pmd_t entry, int dirty)
> +{
> + BUG();
> + return 0;
> +}
Is it possible to simply leave this undefined? So the kernel fails at
link time?
> --- a/mm/pgtable-generic.c
> +++ b/mm/pgtable-generic.c
Good heavens that file is a mess. Your patch does improve it.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 09/11] mm,thp: introduce flush_pmd_tlb_range
[not found] ` <1440666194-21478-10-git-send-email-vgupta@synopsys.com>
@ 2015-09-16 22:26 ` Andrew Morton
0 siblings, 0 replies; 5+ messages in thread
From: Andrew Morton @ 2015-09-16 22:26 UTC (permalink / raw)
To: Vineet Gupta
Cc: Aneesh Kumar K.V, Kirill A. Shutemov, Mel Gorman, Matthew Wilcox,
Minchan Kim, linux-arch, linux-kernel, linux-mm, arc-linux-dev
On Thu, 27 Aug 2015 14:33:12 +0530 Vineet Gupta <Vineet.Gupta1@synopsys.com> wrote:
> --- a/mm/pgtable-generic.c
> +++ b/mm/pgtable-generic.c
> @@ -84,6 +84,19 @@ pte_t ptep_clear_flush(struct vm_area_struct *vma, unsigned long address,
>
> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>
> +#ifndef __HAVE_ARCH_FLUSH_PMD_TLB_RANGE
> +
> +/*
> + * ARCHes with special requirements for evicting THP backing TLB entries can
> + * implement this. Otherwise also, it can help optimizing thp flush operation.
> + * flush_tlb_range() can have optimization to nuke the entire TLB if flush span
> + * is greater than a threashhold, which will likely be true for a single
> + * huge page.
> + * e.g. see arch/arc: flush_pmd_tlb_range
> + */
> +#define flush_pmd_tlb_range(vma, addr, end) flush_tlb_range(vma, addr, end)
> +#endif
Did you consider using a __weak function here?
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 00/11] THP support for ARC
[not found] <1440666194-21478-1-git-send-email-vgupta@synopsys.com>
` (2 preceding siblings ...)
[not found] ` <1440666194-21478-10-git-send-email-vgupta@synopsys.com>
@ 2015-09-16 22:27 ` Andrew Morton
3 siblings, 0 replies; 5+ messages in thread
From: Andrew Morton @ 2015-09-16 22:27 UTC (permalink / raw)
To: Vineet Gupta
Cc: Aneesh Kumar K.V, Kirill A. Shutemov, Mel Gorman, Matthew Wilcox,
Minchan Kim, linux-arch, linux-kernel, linux-mm, arc-linux-dev
On Thu, 27 Aug 2015 14:33:03 +0530 Vineet Gupta <Vineet.Gupta1@synopsys.com> wrote:
> This series brings THP support to ARC. It also introduces an optional new
> thp hook for arches to possibly optimize the TLB flush in thp regime.
The mm/ changes look OK to me. Please maintain them in the arc tree,
merge them upstream at the same time.
^ permalink raw reply [flat|nested] 5+ messages in thread
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2015-08-27 15:32 ` [PATCH 04/11] ARCv2: mm: THP support Kirill A. Shutemov
2015-08-27 16:56 ` Vineet Gupta
[not found] ` <1440666194-21478-9-git-send-email-vgupta@synopsys.com>
2015-09-16 22:25 ` [PATCH 08/11] mm,thp: reduce ifdef'ery for THP in generic code Andrew Morton
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2015-09-16 22:26 ` [PATCH 09/11] mm,thp: introduce flush_pmd_tlb_range Andrew Morton
2015-09-16 22:27 ` [PATCH 00/11] THP support for ARC Andrew Morton
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