The patch titled
Subject: mm-highmem-makes-flush_all_zero_pkmaps-return-index-of-last-flushed-entry-v2
has been added to the -mm tree. Its filename is
mm-highmem-makes-flush_all_zero_pkmaps-return-index-of-last-flushed-entry-v2.patch
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From: Joonsoo Kim <js1304@xxxxxxxxx>
Subject: mm-highmem-makes-flush_all_zero_pkmaps-return-index-of-last-flushed-entry-v2
In current code, after flush_all_zero_pkmaps() is invoked,
then re-iterate all pkmaps. It can be optimized if flush_all_zero_pkmaps()
return index of first flushed entry. With this index,
we can immediately map highmem page to virtual address represented by index.
So change return type of flush_all_zero_pkmaps()
and return index of first flushed entry.
Additionally, update last_pkmap_nr to this index.
It is certain that entry which is below this index is occupied by other mapping,
therefore updating last_pkmap_nr to this index is reasonable optimization.
Signed-off-by: Joonsoo Kim <js1304@xxxxxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/highmem.h | 2 +-
mm/highmem.c | 24 +++++++++++++++---------
2 files changed, 16 insertions(+), 10 deletions(-)
diff -puN include/linux/highmem.h~mm-highmem-makes-flush_all_zero_pkmaps-return-index-of-last-flushed-entry-v2 include/linux/highmem.h
--- a/include/linux/highmem.h~mm-highmem-makes-flush_all_zero_pkmaps-return-index-of-last-flushed-entry-v2
+++ a/include/linux/highmem.h
@@ -32,7 +32,7 @@ static inline void invalidate_kernel_vma
#ifdef CONFIG_HIGHMEM
#include <asm/highmem.h>
-#define PKMAP_INDEX_INVAL (-1)
+#define PKMAP_INVALID_INDEX (LAST_PKMAP)
/* declarations for linux/mm/highmem.c */
unsigned int nr_free_highpages(void);
diff -puN mm/highmem.c~mm-highmem-makes-flush_all_zero_pkmaps-return-index-of-last-flushed-entry-v2 mm/highmem.c
--- a/mm/highmem.c~mm-highmem-makes-flush_all_zero_pkmaps-return-index-of-last-flushed-entry-v2
+++ a/mm/highmem.c
@@ -107,10 +107,10 @@ struct page *kmap_to_page(void *vaddr)
}
EXPORT_SYMBOL(kmap_to_page);
-static int flush_all_zero_pkmaps(void)
+static unsigned int flush_all_zero_pkmaps(void)
{
int i;
- int index = PKMAP_INDEX_INVAL;
+ unsigned int index = PKMAP_INVALID_INDEX;
flush_cache_kmaps();
@@ -142,9 +142,10 @@ static int flush_all_zero_pkmaps(void)
&pkmap_page_table[i]);
set_page_address(page, NULL);
- index = i;
+ if (index == PKMAP_INVALID_INDEX)
+ index = i;
}
- if (index != PKMAP_INDEX_INVAL)
+ if (index != PKMAP_INVALID_INDEX)
flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
return index;
@@ -155,15 +156,19 @@ static int flush_all_zero_pkmaps(void)
*/
void kmap_flush_unused(void)
{
+ unsigned int index;
+
lock_kmap();
- flush_all_zero_pkmaps();
+ index = flush_all_zero_pkmaps();
+ if (index != PKMAP_INVALID_INDEX && (index < last_pkmap_nr))
+ last_pkmap_nr = index;
unlock_kmap();
}
static inline unsigned long map_new_virtual(struct page *page)
{
unsigned long vaddr;
- int index = PKMAP_INDEX_INVAL;
+ unsigned int index = PKMAP_INVALID_INDEX;
int count;
start:
@@ -173,8 +178,7 @@ start:
last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
if (!last_pkmap_nr) {
index = flush_all_zero_pkmaps();
- if (index != PKMAP_INDEX_INVAL)
- break; /* Found a usable entry */
+ break;
}
if (!pkmap_count[last_pkmap_nr]) {
index = last_pkmap_nr;
@@ -187,7 +191,7 @@ start:
/*
* Sleep for somebody else to unmap their entries
*/
- if (index == PKMAP_INDEX_INVAL) {
+ if (index == PKMAP_INVALID_INDEX) {
DECLARE_WAITQUEUE(wait, current);
__set_current_state(TASK_UNINTERRUPTIBLE);
@@ -211,6 +215,7 @@ start:
&(pkmap_page_table[index]), mk_pte(page, kmap_prot));
pkmap_count[index] = 1;
+ last_pkmap_nr = index;
set_page_address(page, (void *)vaddr);
return vaddr;
@@ -332,6 +337,7 @@ struct page_address_map {
void *virtual;
struct list_head list;
};
+
static struct page_address_map page_address_maps[LAST_PKMAP];
/*
_
Patches currently in -mm which might be from js1304@xxxxxxxxx are
linux-next.patch
mm-highmem-use-pkmap_nr-to-calculate-an-index-of-pkmap.patch
mm-highmem-remove-useless-pool_lock.patch
mm-highmem-remove-page_address_pool-list.patch
mm-highmem-remove-page_address_pool-list-v2.patch
mm-highmem-makes-flush_all_zero_pkmaps-return-index-of-last-flushed-entry.patch
mm-highmem-makes-flush_all_zero_pkmaps-return-index-of-last-flushed-entry-v2.patch
mm-highmem-get-virtual-address-of-the-page-using-pkmap_addr.patch
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