Commit b7418510 authored by Seth Jennings's avatar Seth Jennings Committed by Greg Kroah-Hartman
Browse files

staging: zsmalloc: add mapping modes



This patch improves mapping performance in zsmalloc by getting
usage information from the user in the form of a "mapping mode"
and using it to avoid unnecessary copying for objects that span
pages.
Signed-off-by: default avatarSeth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 166cfda7
......@@ -716,7 +716,7 @@ static unsigned long zv_create(struct zs_pool *pool, uint32_t pool_id,
goto out;
atomic_inc(&zv_curr_dist_counts[chunks]);
atomic_inc(&zv_cumul_dist_counts[chunks]);
zv = zs_map_object(pool, handle);
zv = zs_map_object(pool, handle, ZS_MM_WO);
zv->index = index;
zv->oid = *oid;
zv->pool_id = pool_id;
......@@ -735,7 +735,7 @@ static void zv_free(struct zs_pool *pool, unsigned long handle)
uint16_t size;
int chunks;
zv = zs_map_object(pool, handle);
zv = zs_map_object(pool, handle, ZS_MM_RW);
ASSERT_SENTINEL(zv, ZVH);
size = zv->size + sizeof(struct zv_hdr);
INVERT_SENTINEL(zv, ZVH);
......@@ -757,7 +757,7 @@ static void zv_decompress(struct page *page, unsigned long handle)
int ret;
struct zv_hdr *zv;
zv = zs_map_object(zcache_host.zspool, handle);
zv = zs_map_object(zcache_host.zspool, handle, ZS_MM_RO);
BUG_ON(zv->size == 0);
ASSERT_SENTINEL(zv, ZVH);
to_va = kmap_atomic(page);
......
......@@ -220,7 +220,8 @@ static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
uncmem = user_mem;
clen = PAGE_SIZE;
cmem = zs_map_object(zram->mem_pool, zram->table[index].handle);
cmem = zs_map_object(zram->mem_pool, zram->table[index].handle,
ZS_MM_RO);
ret = lzo1x_decompress_safe(cmem, zram->table[index].size,
uncmem, &clen);
......@@ -258,7 +259,7 @@ static int zram_read_before_write(struct zram *zram, char *mem, u32 index)
return 0;
}
cmem = zs_map_object(zram->mem_pool, handle);
cmem = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
ret = lzo1x_decompress_safe(cmem, zram->table[index].size,
mem, &clen);
zs_unmap_object(zram->mem_pool, handle);
......@@ -351,7 +352,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
ret = -ENOMEM;
goto out;
}
cmem = zs_map_object(zram->mem_pool, handle);
cmem = zs_map_object(zram->mem_pool, handle, ZS_MM_WO);
memcpy(cmem, src, clen);
......
......@@ -484,9 +484,6 @@ static void zs_copy_map_object(char *buf, struct page *firstpage,
sizes[0] = PAGE_SIZE - off;
sizes[1] = size - sizes[0];
/* disable page faults to match kmap_atomic() return conditions */
pagefault_disable();
/* copy object to per-cpu buffer */
addr = kmap_atomic(pages[0]);
memcpy(buf, addr + off, sizes[0]);
......@@ -517,9 +514,6 @@ static void zs_copy_unmap_object(char *buf, struct page *firstpage,
addr = kmap_atomic(pages[1]);
memcpy(addr, buf + sizes[0], sizes[1]);
kunmap_atomic(addr);
/* enable page faults to match kunmap_atomic() return conditions */
pagefault_enable();
}
static int zs_cpu_notifier(struct notifier_block *nb, unsigned long action,
......@@ -754,7 +748,8 @@ EXPORT_SYMBOL_GPL(zs_free);
*
* This function returns with preemption and page faults disabled.
*/
void *zs_map_object(struct zs_pool *pool, unsigned long handle)
void *zs_map_object(struct zs_pool *pool, unsigned long handle,
enum zs_mapmode mm)
{
struct page *page;
unsigned long obj_idx, off;
......@@ -778,6 +773,10 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle)
return area->vm_addr + off;
}
/* disable page faults to match kmap_atomic() return conditions */
pagefault_disable();
if (mm != ZS_MM_WO)
zs_copy_map_object(area->vm_buf, page, off, class->size);
area->vm_addr = NULL;
return area->vm_buf;
......@@ -795,13 +794,16 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
struct mapping_area *area;
area = &__get_cpu_var(zs_map_area);
if (area->vm_addr) {
/* single-page object fastpath */
if (area->vm_addr) {
kunmap_atomic(area->vm_addr);
put_cpu_var(zs_map_area);
return;
goto out;
}
/* no write fastpath */
if (area->vm_mm == ZS_MM_RO)
goto pfenable;
BUG_ON(!handle);
obj_handle_to_location(handle, &page, &obj_idx);
......@@ -810,6 +812,11 @@ void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
off = obj_idx_to_offset(page, obj_idx, class->size);
zs_copy_unmap_object(area->vm_buf, page, off, class->size);
pfenable:
/* enable page faults to match kunmap_atomic() return conditions */
pagefault_enable();
out:
put_cpu_var(zs_map_area);
}
EXPORT_SYMBOL_GPL(zs_unmap_object);
......
......@@ -15,6 +15,17 @@
#include <linux/types.h>
/*
* zsmalloc mapping modes
*
* NOTE: These only make a difference when a mapped object spans pages
*/
enum zs_mapmode {
ZS_MM_RW, /* normal read-write mapping */
ZS_MM_RO, /* read-only (no copy-out at unmap time) */
ZS_MM_WO /* write-only (no copy-in at map time) */
};
struct zs_pool;
struct zs_pool *zs_create_pool(const char *name, gfp_t flags);
......@@ -23,7 +34,8 @@ void zs_destroy_pool(struct zs_pool *pool);
unsigned long zs_malloc(struct zs_pool *pool, size_t size);
void zs_free(struct zs_pool *pool, unsigned long obj);
void *zs_map_object(struct zs_pool *pool, unsigned long handle);
void *zs_map_object(struct zs_pool *pool, unsigned long handle,
enum zs_mapmode mm);
void zs_unmap_object(struct zs_pool *pool, unsigned long handle);
u64 zs_get_total_size_bytes(struct zs_pool *pool);
......
......@@ -112,6 +112,7 @@ static const int fullness_threshold_frac = 4;
struct mapping_area {
char *vm_buf; /* copy buffer for objects that span pages */
char *vm_addr; /* address of kmap_atomic()'ed pages */
enum zs_mapmode vm_mm; /* mapping mode */
};
struct size_class {
......
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