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SubjectRe: [PATCH 1/2] alpha: use .data.init_task instead of .data.init_thread.
On Fri, 31 Jul 2009, Richard Henderson wrote:

> On 07/31/2009 02:23 PM, Richard Henderson wrote:
> > Similarly it is *not* a bug that the page_aligned sections were before
> > data, because we already knew we had 2 page alignment from the end of
> > init + 2 pages of init_thread.
>
> Indeed, I'll go further and say that the common definition of RW_DATA_SECTION
> is buggy.
[...]
> Given that we align the entire .data section why have interior padding to
> re-align for page-aligned data? Surely a better ordering would be
[...]

Agreed. I actually commented on this issue in one of the drafts of
RW_DATA_SECTION, but forgot to check again whether Sam had addressed it
when reviewing the final version. Fortunately we're talking about a small
inefficiency, not something more serious. Below is your proposed change
in patch form; I hope Sam will take a look at it.

-Tim Abbott

Optimize the ordering of sections in RW_DATA_SECTION.

The current RW_DATA_SECTION macro doesn't place the various
PAGE_SIZE-aligned sections next to each other. This could result in up to
a page of memory being wasted realigning to PAGE_SIZE twice.

Signed-off-by: Tim Abbott <tabbott@ksplice.com>
---
include/asm-generic/vmlinux.lds.h | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 6ad76bf..146815d 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -706,12 +706,12 @@
. = ALIGN(PAGE_SIZE); \
.data : AT(ADDR(.data) - LOAD_OFFSET) { \
INIT_TASK_DATA(inittask) \
+ NOSAVE_DATA \
+ PAGE_ALIGNED_DATA(pagealigned) \
CACHELINE_ALIGNED_DATA(cacheline) \
READ_MOSTLY_DATA(cacheline) \
DATA_DATA \
CONSTRUCTORS \
- NOSAVE_DATA \
- PAGE_ALIGNED_DATA(pagealigned) \
}

#define INIT_TEXT_SECTION(inittext_align) \
--
1.6.3.3


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