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 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 last flushed entry.
Signed-off-by: Joonsoo Kim <js1...@gmail.com>
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index ef788b5..0683869 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -32,6 +32,7 @@ static inline void invalidate_kernel_vmap_range(void *vaddr,
int size)
#ifdef CONFIG_HIGHMEM
#include <asm/highmem.h>
+#define PKMAP_INDEX_INVAL (-1)
/* declarations for linux/mm/highmem.c */
unsigned int nr_free_highpages(void);
diff --git a/mm/highmem.c b/mm/highmem.c
index 731cf9a..65beb9a 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -106,10 +106,10 @@ struct page *kmap_to_page(void *vaddr)
return virt_to_page(addr);
}
-static void flush_all_zero_pkmaps(void)
+static int flush_all_zero_pkmaps(void)
{
int i;
- int need_flush = 0;
+ int index = PKMAP_INDEX_INVAL;
flush_cache_kmaps();
@@ -141,10 +141,12 @@ static void flush_all_zero_pkmaps(void)
&pkmap_page_table[i]);
set_page_address(page, NULL);
- need_flush = 1;
+ index = i;
}
- if (need_flush)
+ if (index != PKMAP_INDEX_INVAL)
flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
+
+ return index;
}
/**
@@ -160,6 +162,7 @@ void kmap_flush_unused(void)
static inline unsigned long map_new_virtual(struct page *page)
{
unsigned long vaddr;
+ int index = PKMAP_INDEX_INVAL;
int count;
start:
@@ -168,40 +171,45 @@ start:
for (;;) {
last_pkmap_nr = (last_pkmap_nr + 1) & LAST_PKMAP_MASK;
if (!last_pkmap_nr) {
- flush_all_zero_pkmaps();
- count = LAST_PKMAP;
+ index = flush_all_zero_pkmaps();
+ if (index != PKMAP_INDEX_INVAL)
+ break; /* Found a usable entry */
}
- if (!pkmap_count[last_pkmap_nr])
+ if (!pkmap_count[last_pkmap_nr]) {
+ index = last_pkmap_nr;
break; /* Found a usable entry */
- if (--count)
- continue;
-
- /*
- * Sleep for somebody else to unmap their entries
- */
- {
- DECLARE_WAITQUEUE(wait, current);
-
- __set_current_state(TASK_UNINTERRUPTIBLE);
- add_wait_queue(&pkmap_map_wait, &wait);
- unlock_kmap();
- schedule();
- remove_wait_queue(&pkmap_map_wait, &wait);
- lock_kmap();
-
- /* Somebody else might have mapped it while we slept */
- if (page_address(page))
- return (unsigned long)page_address(page);
-
- /* Re-start */
- goto start;
}
+ if (--count == 0)
+ break;
}
- vaddr = PKMAP_ADDR(last_pkmap_nr);
+
+ /*
+ * Sleep for somebody else to unmap their entries
+ */
+ if (index == PKMAP_INDEX_INVAL) {
+ DECLARE_WAITQUEUE(wait, current);
+
+ __set_current_state(TASK_UNINTERRUPTIBLE);
+ add_wait_queue(&pkmap_map_wait, &wait);
+ unlock_kmap();
+ schedule();
+ remove_wait_queue(&pkmap_map_wait, &wait);
+ lock_kmap();
+
+ /* Somebody else might have mapped it while we slept */
+ vaddr = (unsigned long)page_address(page);
+ if (vaddr)
+ return vaddr;
+
+ /* Re-start */
+ goto start;
+ }
+
+ vaddr = PKMAP_ADDR(index);
set_pte_at(&init_mm, vaddr,
- &(pkmap_page_table[last_pkmap_nr]), mk_pte(page, kmap_prot));
+ &(pkmap_page_table[index]), mk_pte(page, kmap_prot));
- pkmap_count[last_pkmap_nr] = 1;
+ pkmap_count[index] = 1;
set_page_address(page, (void *)vaddr);
return vaddr;
--
1.7.9.5
--
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