On 02.03.2007 [18:24:26 +1100], David Gibson wrote:
> On Wed, Feb 28, 2007 at 08:22:36AM -0800, Nishanth Aravamudan wrote:
> > On 27.02.2007 [10:47:31 +1100], David Gibson wrote:
> > > On Mon, Feb 26, 2007 at 03:21:26PM -0800, Nishanth Aravamudan wrote:
> > > > Author: Nishanth Aravamudan <[EMAIL PROTECTED]>
> > > > Date: Mon Feb 26 15:17:54 2007 -0800
> > > >
> > > > hugeutils: add address parameter to hugetlbfs_vaddr_granularity
> > > >
> > > > On ppc64, the actual granularity of hugepage requests depends on the
> > > > address in question. Specify the three cases (0-4G, 4G-1TB, 1TB+) in the
> > > > function. This is useful for the partial_remap code, as it would
> > > > (effectively) never run on ppc64 otherwise (would need a 1TB or larger
> > > > segment, without relinking).
> > >
> > > I've thought about doing something like this before. However, the
> > > semantics as they stand are a little bit fuzzy. What I'd prefer, if
> > > you want to get finer-grained information about the page-size regions
> > > is a pair of functions to find the end and beginning of a page-size
> > > slice, given an address. So:
> > >
> > > void *hugetlbfs_slice_end(void *addr);
> > > void *hugetlbfs_slice_start(void *addr);
> > >
> > > The "slice" terminology is something BenH has started using for these
> > > address space regionsin some recent kernel patches.
> >
> > I'm willing to believe I'm doing something incredibly stupid, but here's
> > my patch. I had to use a bunch of macros, as I was getting a headache
> > from all the casts and the constants. How do I make this cleaner? Or do
> > I give up on this?
>
> Well, for starters, you want to get rid of
> hugetlbfs_vaddr_granularity() entirely.
<snip>
> Except.. I think hugetlbfs_slice_end() will actually need to return
> the end of the slice, not the beginning of the next one as it does
> now. I don't like that semantic on the whole, but without it, for
> 32-bit programs hugetlbfs_slice_end() will return 0 for sufficiently
> high addresses. I'd prefer to reserve the case where
> hugetlbfs_slice_end(adde) < addr to mean that the given address is
> already outside the potentially valid range for hugepage addresses (so
> if we ever support ia64, slice_start() and slice_end() end would
> return the constant addresses marking the ends of their fixed hugepage
> region).
Thanks for the review David. I'm not entirely sure about the semantics
still. I got what you were saying, but wasn't sure of the best way to
implement it.
So does something like the following look better?
Signed-off-by: Nishanth Aravamudan <[EMAIL PROTECTED]>
diff --git a/hugetlbfs.h b/hugetlbfs.h
index 966e57c..d0ad9a2 100644
--- a/hugetlbfs.h
+++ b/hugetlbfs.h
@@ -22,7 +22,8 @@
#define HUGETLBFS_MAGIC 0x958458f6
long gethugepagesize(void);
-long hugetlbfs_vaddr_granularity(void);
+void *hugetlbfs_slice_start(void *);
+void *hugetlbfs_slice_end(void *);
int hugetlbfs_test_path(const char *mount);
const char *hugetlbfs_find_path(void);
int hugetlbfs_unlinked_fd(void);
diff --git a/hugeutils.c b/hugeutils.c
index 9af92b9..d8fb679 100644
--- a/hugeutils.c
+++ b/hugeutils.c
@@ -114,14 +114,36 @@ long gethugepagesize(void)
return hpage_size;
}
-long hugetlbfs_vaddr_granularity(void)
-{
+/*
+ * Return the address of the start and end of the hugetlb slice
+ * containing @addr. A slice is a range of addresses, start inclusive
+ * and end exclusive.
+ */
+void *hugetlbfs_slice_start(void *addr) {
#if defined(__powerpc64__)
- return (1L << 40);
+ if (addr < (void *)SLICE_LOW_TOP)
+ return ALIGN_PTR_DOWN(addr, SLICE_LOW_SIZE);
+ else if (addr < (void *)SLICE_HIGH_SIZE)
+ return (void *)SLICE_LOW_TOP;
+ else
+ return ALIGN_PTR_DOWN(addr, SLICE_HIGH_SIZE);
+#elif defined(__powerpc__)
+ return ALIGN_PTR_DOWN(addr, SLICE_LOW_SIZE);
+#else
+ return ALIGN_PTR_DOWN(addr, gethugepagesize());
+#endif
+}
+
+void *hugetlbfs_slice_end(void *addr) {
+#if defined(__powerpc64__)
+ if (addr < (void *)SLICE_LOW_TOP)
+ return ALIGN_PTR_UP(addr, SLICE_LOW_SIZE) - 1;
+ else
+ return ALIGN_PTR_UP(addr, SLICE_HIGH_SIZE) - 1;
#elif defined(__powerpc__)
- return (1L << 28);
+ return ALIGN_PTR_UP(addr, SLICE_LOW_SIZE) - 1;
#else
- return gethugepagesize();
+ return ALIGN_PTR_UP(addr, gethugepagesize()) - 1;
#endif
}
diff --git a/libhugetlbfs_internal.h b/libhugetlbfs_internal.h
index 40da66a..8e5f6fe 100644
--- a/libhugetlbfs_internal.h
+++ b/libhugetlbfs_internal.h
@@ -26,7 +26,18 @@
#define stringify_1(x) #x
#define stringify(x) stringify_1(x)
-#define ALIGN(x, a) (((x) + (a) - 1) & ~((a) - 1))
+#define SLICE_LOW_SHIFT 28
+#define SLICE_HIGH_SHIFT 40
+
+#define SLICE_LOW_TOP (0x100000000UL)
+#define SLICE_LOW_SIZE (1UL << SLICE_LOW_SHIFT)
+#define SLICE_HIGH_SIZE (1UL << SLICE_HIGH_SHIFT)
+
+#define ALIGN_UP(x, a) (((x) + (a) - 1) & ~((a) - 1))
+#define ALIGN_DOWN(x, a) ((x) & ~((a) - 1))
+#define ALIGN(x,a) ALIGN_UP(x,a)
+#define ALIGN_PTR_UP(x, a) (void *)ALIGN_UP((unsigned long)x, a)
+#define ALIGN_PTR_DOWN(x,a) (void *)ALIGN_DOWN((unsigned long)x, a)
extern int __hugetlbfs_verbose;
diff --git a/morecore.c b/morecore.c
index 25c2d27..ba4fcb0 100644
--- a/morecore.c
+++ b/morecore.c
@@ -166,7 +166,7 @@ static void __attribute__((constructor))
setup_morecore(void)
}
} else {
heapaddr = (unsigned long)sbrk(0);
- heapaddr = ALIGN(heapaddr, hugetlbfs_vaddr_granularity());
+ heapaddr = ALIGN(heapaddr, (unsigned
long)hugetlbfs_slice_end((void *)heapaddr) + 1);
}
DEBUG("setup_morecore(): heapaddr = 0x%lx\n", heapaddr);
--
Nishanth Aravamudan <[EMAIL PROTECTED]>
IBM Linux Technology Center
-------------------------------------------------------------------------
Take Surveys. Earn Cash. Influence the Future of IT
Join SourceForge.net's Techsay panel and you'll get the chance to share your
opinions on IT & business topics through brief surveys-and earn cash
http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
_______________________________________________
Libhugetlbfs-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/libhugetlbfs-devel
