From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Mel Gorman <mgorman@suse.de>,
Matthew Wilcox <matthew.r.wilcox@intel.com>,
Minchan Kim <minchan@kernel.org>,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [PATCH v2 09/12] mm,thp: reduce ifdef'ery for THP in generic code
Date: Fri, 9 Oct 2015 12:53:59 +0300 [thread overview]
Message-ID: <20151009095359.GA7971@node> (raw)
In-Reply-To: <1442918096-17454-10-git-send-email-vgupta@synopsys.com>
On Tue, Sep 22, 2015 at 04:04:53PM +0530, Vineet Gupta wrote:
> - pgtable-generic.c: Fold individual #ifdef for each helper into a top
> level #ifdef. Makes code more readable
Makes sense.
> - Per Andrew's suggestion removed the dummy implementations for !THP
> in asm-generic/page-table.h to have build time failures vs. runtime.
I'm not sure it's a good idea. This can lead to unnecessary #ifdefs where
otherwise call to helper would be eliminated by compiler as dead code.
What about dummy helpers with BUILD_BUG()?
> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
> ---
> include/asm-generic/pgtable.h | 49 ++++++++++++++++---------------------------
> mm/pgtable-generic.c | 24 +++------------------
> 2 files changed, 21 insertions(+), 52 deletions(-)
>
> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
> index 29c57b2cb344..2112f4147816 100644
> --- a/include/asm-generic/pgtable.h
> +++ b/include/asm-generic/pgtable.h
> @@ -30,9 +30,12 @@ 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);
> +
> +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
> #endif
>
> #ifndef __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
> @@ -64,14 +67,6 @@ static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
> set_pmd_at(vma->vm_mm, address, pmdp, pmd_mkold(pmd));
> return r;
> }
> -#else /* CONFIG_TRANSPARENT_HUGEPAGE */
> -static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
> - unsigned long address,
> - pmd_t *pmdp)
> -{
> - BUG();
> - return 0;
> -}
> #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
> #endif
>
> @@ -81,8 +76,21 @@ int ptep_clear_flush_young(struct vm_area_struct *vma,
> #endif
>
> #ifndef __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
> -int pmdp_clear_flush_young(struct vm_area_struct *vma,
> - unsigned long address, pmd_t *pmdp);
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +extern int pmdp_clear_flush_young(struct vm_area_struct *vma,
> + unsigned long address, pmd_t *pmdp);
> +#else
> +/*
> + * Despite relevant to THP only, this API is called from generic rmap code
> + * under PageTransHuge(), hence needs a dummy implementation for !THP
> + */
Looks like a case I described above. BUILD_BUG_ON() should work fine here.
> +static inline int pmdp_clear_flush_young(struct vm_area_struct *vma,
> + unsigned long address, pmd_t *pmdp)
> +{
> + BUG();
> + return 0;
> +}
> +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
> #endif
--
Kirill A. Shutemov
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WARNING: multiple messages have this Message-ID (diff)
From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Mel Gorman <mgorman@suse.de>,
Matthew Wilcox <matthew.r.wilcox@intel.com>,
Minchan Kim <minchan@kernel.org>,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [PATCH v2 09/12] mm,thp: reduce ifdef'ery for THP in generic code
Date: Fri, 9 Oct 2015 12:53:59 +0300 [thread overview]
Message-ID: <20151009095359.GA7971@node> (raw)
Message-ID: <20151009095359.GAurDeIYsFl5ZKF69lQ6ssmVZsr271DME9wORmeTs6k@z> (raw)
In-Reply-To: <1442918096-17454-10-git-send-email-vgupta@synopsys.com>
On Tue, Sep 22, 2015 at 04:04:53PM +0530, Vineet Gupta wrote:
> - pgtable-generic.c: Fold individual #ifdef for each helper into a top
> level #ifdef. Makes code more readable
Makes sense.
> - Per Andrew's suggestion removed the dummy implementations for !THP
> in asm-generic/page-table.h to have build time failures vs. runtime.
I'm not sure it's a good idea. This can lead to unnecessary #ifdefs where
otherwise call to helper would be eliminated by compiler as dead code.
What about dummy helpers with BUILD_BUG()?
> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
> ---
> include/asm-generic/pgtable.h | 49 ++++++++++++++++---------------------------
> mm/pgtable-generic.c | 24 +++------------------
> 2 files changed, 21 insertions(+), 52 deletions(-)
>
> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
> index 29c57b2cb344..2112f4147816 100644
> --- a/include/asm-generic/pgtable.h
> +++ b/include/asm-generic/pgtable.h
> @@ -30,9 +30,12 @@ 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);
> +
> +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
> #endif
>
> #ifndef __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
> @@ -64,14 +67,6 @@ static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
> set_pmd_at(vma->vm_mm, address, pmdp, pmd_mkold(pmd));
> return r;
> }
> -#else /* CONFIG_TRANSPARENT_HUGEPAGE */
> -static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
> - unsigned long address,
> - pmd_t *pmdp)
> -{
> - BUG();
> - return 0;
> -}
> #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
> #endif
>
> @@ -81,8 +76,21 @@ int ptep_clear_flush_young(struct vm_area_struct *vma,
> #endif
>
> #ifndef __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
> -int pmdp_clear_flush_young(struct vm_area_struct *vma,
> - unsigned long address, pmd_t *pmdp);
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +extern int pmdp_clear_flush_young(struct vm_area_struct *vma,
> + unsigned long address, pmd_t *pmdp);
> +#else
> +/*
> + * Despite relevant to THP only, this API is called from generic rmap code
> + * under PageTransHuge(), hence needs a dummy implementation for !THP
> + */
Looks like a case I described above. BUILD_BUG_ON() should work fine here.
> +static inline int pmdp_clear_flush_young(struct vm_area_struct *vma,
> + unsigned long address, pmd_t *pmdp)
> +{
> + BUG();
> + return 0;
> +}
> +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
> #endif
--
Kirill A. Shutemov
next prev parent reply other threads:[~2015-10-09 9:53 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-22 10:34 [PATCH v2 00/12] THP support for ARC Vineet Gupta
2015-09-22 10:34 ` [PATCH v2 01/12] ARC: mm: switch pgtable_to to pte_t * Vineet Gupta
2015-09-22 10:34 ` [PATCH v2 02/12] ARC: mm: pte flags comsetic cleanups, comments Vineet Gupta
2015-09-22 10:34 ` [PATCH v2 03/12] ARC: mm: Introduce PTE_SPECIAL Vineet Gupta
2015-09-22 10:34 ` [PATCH v2 04/12] Documentation/features/vm: pte_special now supported by ARC Vineet Gupta
2015-09-22 10:34 ` [PATCH v2 05/12] ARCv2: mm: THP support Vineet Gupta
2015-09-22 10:34 ` [PATCH v2 06/12] ARCv2: mm: THP: boot validation/reporting Vineet Gupta
2015-09-22 10:34 ` [PATCH v2 07/12] Documentation/features/vm: THP now supported by ARC Vineet Gupta
2015-09-22 10:34 ` [PATCH v2 08/12] mm: move some code around Vineet Gupta
2015-10-09 9:48 ` Kirill A. Shutemov
2015-10-09 9:48 ` Kirill A. Shutemov
2015-10-09 10:01 ` Vineet Gupta
2015-09-22 10:34 ` [PATCH v2 09/12] mm,thp: reduce ifdef'ery for THP in generic code Vineet Gupta
2015-10-09 9:53 ` Kirill A. Shutemov [this message]
2015-10-09 9:53 ` Kirill A. Shutemov
2015-10-09 10:10 ` Vineet Gupta
2015-10-09 10:28 ` Vineet Gupta
2015-09-22 10:34 ` [PATCH v2 10/12] mm,thp: introduce flush_pmd_tlb_range Vineet Gupta
2015-10-09 10:08 ` Kirill A. Shutemov
2015-10-09 10:08 ` Kirill A. Shutemov
2015-10-09 10:54 ` Vineet Gupta
2015-09-22 10:34 ` [PATCH v2 11/12] ARCv2: mm: THP: Implement flush_pmd_tlb_range() optimization Vineet Gupta
2015-09-22 10:34 ` [PATCH v2 12/12] ARCv2: Add a DT which enables THP Vineet Gupta
2015-10-01 6:02 ` [PATCH v2 00/12] THP support for ARC Vineet Gupta
2015-10-09 9:33 ` Vineet Gupta
2015-10-09 10:10 ` Kirill A. Shutemov
2015-10-09 11:29 ` Vineet Gupta
2015-10-09 11:43 ` Kirill A. Shutemov
2015-10-09 11:43 ` Kirill A. Shutemov
2015-10-09 11:52 ` Vineet Gupta
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