Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1214588 > unrolled thread
| Started by | "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> |
|---|---|
| First post | 2015-08-27 16:10 +0200 |
| Last post | 2015-08-27 17:20 +0200 |
| Articles | 2 — 2 participants |
Back to article view | Back to linux.kernel
This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by
below is the oldest one visible, not the original post.
[PATCHv4 7/7] mm: use 'unsigned int' for compound_dtor/compound_order on 64BIT "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2015-08-27 16:10 +0200
Re: [PATCHv4 7/7] mm: use 'unsigned int' for compound_dtor/compound_order on 64BIT Michal Hocko <mhocko@kernel.org> - 2015-08-27 17:20 +0200
| From | "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> |
|---|---|
| Date | 2015-08-27 16:10 +0200 |
| Subject | [PATCHv4 7/7] mm: use 'unsigned int' for compound_dtor/compound_order on 64BIT |
| Message-ID | <q262m-6Gi-15@gated-at.bofh.it> |
On 64 bit system we have enough space in struct page to encode
compound_dtor and compound_order with unsigned int.
On x86-64 it leads to slightly smaller code size due usesage of plain
MOV instead of MOVZX (zero-extended move) or similar effect.
allyesconfig:
text data bss dec hex filename
159520446 48146736 72196096 279863278 10ae5fee vmlinux.pre
159520382 48146736 72196096 279863214 10ae5fae vmlinux.post
On other architectures without native support of 16-bit data types the
difference can be bigger.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
include/linux/mm_types.h | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index ecaf3b1d0216..39b0db74ba5e 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -150,8 +150,13 @@ struct page {
/* First tail page of compound page */
struct {
unsigned long compound_head; /* If bit zero is set */
+#ifdef CONFIG_64BIT
+ unsigned int compound_dtor;
+ unsigned int compound_order;
+#else
unsigned short int compound_dtor;
unsigned short int compound_order;
+#endif
};
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && USE_SPLIT_PMD_PTLOCKS
--
2.5.0
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[toc] | [next] | [standalone]
| From | Michal Hocko <mhocko@kernel.org> |
|---|---|
| Date | 2015-08-27 17:20 +0200 |
| Subject | Re: [PATCHv4 7/7] mm: use 'unsigned int' for compound_dtor/compound_order on 64BIT |
| Message-ID | <q2786-8ds-17@gated-at.bofh.it> |
| In reply to | #1214588 |
On Thu 27-08-15 16:59:21, Kirill A. Shutemov wrote:
> On 64 bit system we have enough space in struct page to encode
> compound_dtor and compound_order with unsigned int.
>
> On x86-64 it leads to slightly smaller code size due usesage of plain
> MOV instead of MOVZX (zero-extended move) or similar effect.
>
> allyesconfig:
>
> text data bss dec hex filename
> 159520446 48146736 72196096 279863278 10ae5fee vmlinux.pre
> 159520382 48146736 72196096 279863214 10ae5fae vmlinux.post
64B is not much, really, but if that works as a microptimization then I
have no objections.
> On other architectures without native support of 16-bit data types the
> difference can be bigger.
Thank you for pulling this out of the original patch.
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
> ---
> include/linux/mm_types.h | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index ecaf3b1d0216..39b0db74ba5e 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -150,8 +150,13 @@ struct page {
> /* First tail page of compound page */
> struct {
> unsigned long compound_head; /* If bit zero is set */
> +#ifdef CONFIG_64BIT
> + unsigned int compound_dtor;
> + unsigned int compound_order;
> +#else
> unsigned short int compound_dtor;
> unsigned short int compound_order;
> +#endif
> };
>
> #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && USE_SPLIT_PMD_PTLOCKS
> --
> 2.5.0
--
Michal Hocko
SUSE Labs
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[toc] | [prev] | [standalone]
Back to top | Article view | linux.kernel
csiph-web