[patch 1/1] powerpc: hugetlb pgtable cache access cleanup

[patch 1/1] powerpc: hugetlb pgtable cache access cleanup

[akpm]

From: Jon Tollefson <kniht@linux.vnet.ibm.com>

Cleaned up use of macro.  We now reference the pgtable_cache array
directly instead of using a macro.

Signed-off-by: Jon Tollefson <kniht@linux.vnet.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/powerpc/mm/hugetlbpage.c |   22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff -puN arch/powerpc/mm/hugetlbpage.c~powerpc-hugetlb-pgtable-cache-access-cleanup arch/powerpc/mm/hugetlbpage.c
--- a/arch/powerpc/mm/hugetlbpage.c~powerpc-hugetlb-pgtable-cache-access-cleanup
+++ a/arch/powerpc/mm/hugetlbpage.c
@@ -53,8 +53,7 @@ unsigned int mmu_huge_psizes[MMU_PAGE_CO
 
 /* Subtract one from array size because we don't need a cache for 4K since
  * is not a huge page size */
-#define huge_pgtable_cache(psize)	(pgtable_cache[HUGEPTE_CACHE_NUM \
-							+ psize-1])
+#define HUGE_PGTABLE_INDEX(psize)	(HUGEPTE_CACHE_NUM + psize - 1)
 #define HUGEPTE_CACHE_NAME(psize)	(huge_pgtable_cache_name[psize])
 
 static const char *huge_pgtable_cache_name[MMU_PAGE_COUNT] = {
@@ -113,7 +112,7 @@ static inline pte_t *hugepte_offset(huge
 static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp,
 			   unsigned long address, unsigned int psize)
 {
-	pte_t *new = kmem_cache_zalloc(huge_pgtable_cache(psize),
+	pte_t *new = kmem_cache_zalloc(pgtable_cache[HUGE_PGTABLE_INDEX(psize)],
 				      GFP_KERNEL|__GFP_REPEAT);
 
 	if (! new)
@@ -121,7 +120,7 @@ static int __hugepte_alloc(struct mm_str
 
 	spin_lock(&mm->page_table_lock);
 	if (!hugepd_none(*hpdp))
-		kmem_cache_free(huge_pgtable_cache(psize), new);
+		kmem_cache_free(pgtable_cache[HUGE_PGTABLE_INDEX(psize)], new);
 	else
 		hpdp->pd = (unsigned long)new | HUGEPD_OK;
 	spin_unlock(&mm->page_table_lock);
@@ -760,13 +759,14 @@ static int __init hugetlbpage_init(void)
 
 	for (psize = 0; psize < MMU_PAGE_COUNT; ++psize) {
 		if (mmu_huge_psizes[psize]) {
-			huge_pgtable_cache(psize) = kmem_cache_create(
-						HUGEPTE_CACHE_NAME(psize),
-						HUGEPTE_TABLE_SIZE(psize),
-						HUGEPTE_TABLE_SIZE(psize),
-						0,
-						NULL);
-			if (!huge_pgtable_cache(psize))
+			pgtable_cache[HUGE_PGTABLE_INDEX(psize)] =
+				kmem_cache_create(
+					HUGEPTE_CACHE_NAME(psize),
+					HUGEPTE_TABLE_SIZE(psize),
+					HUGEPTE_TABLE_SIZE(psize),
+					0,
+					NULL);
+			if (!pgtable_cache[HUGE_PGTABLE_INDEX(psize)])
 				panic("hugetlbpage_init(): could not create %s"\
 				      "\n", HUGEPTE_CACHE_NAME(psize));
 		}
_

Re: [patch 1/1] powerpc: hugetlb pgtable cache access cleanup

[David Gibson]

On Wed, Oct 29, 2008 at 02:18:30PM -0700, akpm@linux-foundation.org wrote:
> From: Jon Tollefson <kniht@linux.vnet.ibm.com>
> 
> Cleaned up use of macro.  We now reference the pgtable_cache array
> directly instead of using a macro.
> 
> Signed-off-by: Jon Tollefson <kniht@linux.vnet.ibm.com>
> Cc: Nick Piggin <nickpiggin@yahoo.com.au>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Well, I'm not entirely sure I see the point.  But I don't see anything
broken about it.

Acked-by: David Gibson <david@gibson.dropbear.id.au>

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

Re: [patch 1/1] powerpc: hugetlb pgtable cache access cleanup

[Paul Mackerras]

akpm@linux-foundation.org writes:

> From: Jon Tollefson <kniht@linux.vnet.ibm.com>
> 
> Cleaned up use of macro.  We now reference the pgtable_cache array
> directly instead of using a macro.
> 
> Signed-off-by: Jon Tollefson <kniht@linux.vnet.ibm.com>
> Cc: Nick Piggin <nickpiggin@yahoo.com.au>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

As David Gibson noted, the patch description fails to tell us why this
is a good thing to do (and it isn't immediately obvious to me why it
would be good to make this change).  Jon, please resubmit with a
description that includes the motivation for the change.

Paul.