mm: remove quicklist page table caches

Patch series "mm: remove quicklist page table caches".

A while ago Nicholas proposed to remove quicklist page table caches [1].

I've rebased his patch on the curren upstream and switched ia64 and sh to
use generic versions of PTE allocation.

[1] https://lore.kernel.org/linux-mm/20190711030339.20892-1-npiggin@gmail.com

This patch (of 3):

Remove page table allocator "quicklists".  These have been around for a
long time, but have not got much traction in the last decade and are only
used on ia64 and sh architectures.

The numbers in the initial commit look interesting but probably don't
apply anymore.  If anybody wants to resurrect this it's in the git
history, but it's unhelpful to have this code and divergent allocator
behaviour for minor archs.

Also it might be better to instead make more general improvements to page
allocator if this is still so slow.

Link: http://lkml.kernel.org/r/1565250728-21721-2-git-send-email-rppt@linux.ibm.com
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 7 insertions, 86 deletions

diff --git a/arch/microblaze/include/asm/pgalloc.h b/arch/microblaze/include/asm/pgalloc.h
index f4cc9ffc449e..ac0731881751 100644
--- a/arch/microblaze/include/asm/pgalloc.h
+++ b/arch/microblaze/include/asm/pgalloc.h
@@ -21,83 +21,20 @@
 #include <asm/cache.h>
 #include <asm/pgtable.h>
 
-#define PGDIR_ORDER	0
-
-/*
- * This is handled very differently on MicroBlaze since out page tables
- * are all 0's and I want to be able to use these zero'd pages elsewhere
- * as well - it gives us quite a speedup.
- * -- Cort
- */
-extern struct pgtable_cache_struct {
-	unsigned long *pgd_cache;
-	unsigned long *pte_cache;
-	unsigned long pgtable_cache_sz;
-} quicklists;
-
-#define pgd_quicklist		(quicklists.pgd_cache)
-#define pmd_quicklist		((unsigned long *)0)
-#define pte_quicklist		(quicklists.pte_cache)
-#define pgtable_cache_size	(quicklists.pgtable_cache_sz)
-
-extern unsigned long *zero_cache; /* head linked list of pre-zero'd pages */
-extern atomic_t zero_sz; /* # currently pre-zero'd pages */
-extern atomic_t zeropage_hits; /* # zero'd pages request that we've done */
-extern atomic_t zeropage_calls; /* # zero'd pages request that've been made */
-extern atomic_t zerototal; /* # pages zero'd over time */
-
-#define zero_quicklist		(zero_cache)
-#define zero_cache_sz	 	(zero_sz)
-#define zero_cache_calls	(zeropage_calls)
-#define zero_cache_hits		(zeropage_hits)
-#define zero_cache_total	(zerototal)
-
-/*
- * return a pre-zero'd page from the list,
- * return NULL if none available -- Cort
- */
-extern unsigned long get_zero_page_fast(void);
-
 extern void __bad_pte(pmd_t *pmd);
 
-static inline pgd_t *get_pgd_slow(void)
+static inline pgd_t *get_pgd(void)
 {
-	pgd_t *ret;
-
-	ret = (pgd_t *)__get_free_pages(GFP_KERNEL, PGDIR_ORDER);
-	if (ret != NULL)
-		clear_page(ret);
-	return ret;
+	return (pgd_t *)__get_free_pages(GFP_KERNEL|__GFP_ZERO, 0);
 }
 
-static inline pgd_t *get_pgd_fast(void)
-{
-	unsigned long *ret;
-
-	ret = pgd_quicklist;
-	if (ret != NULL) {
-		pgd_quicklist = (unsigned long *)(*ret);
-		ret[0] = 0;
-		pgtable_cache_size--;
-	} else
-		ret = (unsigned long *)get_pgd_slow();
-	return (pgd_t *)ret;
-}
-
-static inline void free_pgd_fast(pgd_t *pgd)
-{
-	*(unsigned long **)pgd = pgd_quicklist;
-	pgd_quicklist = (unsigned long *) pgd;
-	pgtable_cache_size++;
-}
-
-static inline void free_pgd_slow(pgd_t *pgd)
+static inline void free_pgd(pgd_t *pgd)
 {
 	free_page((unsigned long)pgd);
 }
 
-#define pgd_free(mm, pgd)        free_pgd_fast(pgd)
-#define pgd_alloc(mm)		get_pgd_fast()
+#define pgd_free(mm, pgd)	free_pgd(pgd)
+#define pgd_alloc(mm)		get_pgd()
 
 #define pmd_pgtable(pmd)	pmd_page(pmd)
 
@@ -115,15 +52,14 @@ static inline struct page *pte_alloc_one(struct mm_struct *mm)
 	struct page *ptepage;
 
 #ifdef CONFIG_HIGHPTE
-	int flags = GFP_KERNEL | __GFP_HIGHMEM;
+	int flags = GFP_KERNEL | __GFP_ZERO | __GFP_HIGHMEM;
 #else
-	int flags = GFP_KERNEL;
+	int flags = GFP_KERNEL | __GFP_ZERO;
 #endif
 
 	ptepage = alloc_pages(flags, 0);
 	if (!ptepage)
 		return NULL;
-	clear_highpage(ptepage);
 	if (!pgtable_page_ctor(ptepage)) {
 		__free_page(ptepage);
 		return NULL;
@@ -131,13 +67,6 @@ static inline struct page *pte_alloc_one(struct mm_struct *mm)
 	return ptepage;
 }
 
-static inline void pte_free_fast(pte_t *pte)
-{
-	*(unsigned long **)pte = pte_quicklist;
-	pte_quicklist = (unsigned long *) pte;
-	pgtable_cache_size++;
-}
-
 static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
 {
 	free_page((unsigned long)pte);
@@ -171,10 +100,6 @@ static inline void pte_free(struct mm_struct *mm, struct page *ptepage)
 #define __pmd_free_tlb(tlb, x, addr)	pmd_free((tlb)->mm, x)
 #define pgd_populate(mm, pmd, pte)	BUG()
 
-extern int do_check_pgt_cache(int, int);
-
 #endif /* CONFIG_MMU */
 
-#define check_pgt_cache()		do { } while (0)
-
 #endif /* _ASM_MICROBLAZE_PGALLOC_H */
diff --git a/arch/microblaze/mm/pgtable.c b/arch/microblaze/mm/pgtable.c
index 8fe54fda31dc..010bb9cee2e4 100644
--- a/arch/microblaze/mm/pgtable.c
+++ b/arch/microblaze/mm/pgtable.c
@@ -44,10 +44,6 @@ unsigned long ioremap_base;
 unsigned long ioremap_bot;
 EXPORT_SYMBOL(ioremap_bot);
 
-#ifndef CONFIG_SMP
-struct pgtable_cache_struct quicklists;
-#endif
-
 static void __iomem *__ioremap(phys_addr_t addr, unsigned long size,
 		unsigned long flags)
 {