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Date: Mon, 2 Jul 2012 16:15:52 -0500
From: Seth Jennings <sjenning@...ux.vnet.ibm.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Seth Jennings <sjenning@...ux.vnet.ibm.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Dan Magenheimer <dan.magenheimer@...cle.com>,
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
Nitin Gupta <ngupta@...are.org>,
Minchan Kim <minchan@...nel.org>,
Robert Jennings <rcj@...ux.vnet.ibm.com>, linux-mm@...ck.org,
devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: [PATCH 4/4] 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: Seth Jennings <sjenning@...ux.vnet.ibm.com>
---
drivers/staging/zcache/zcache-main.c | 6 +++---
drivers/staging/zram/zram_drv.c | 7 ++++---
drivers/staging/zsmalloc/zsmalloc-main.c | 29 ++++++++++++++++++-----------
drivers/staging/zsmalloc/zsmalloc.h | 14 +++++++++++++-
drivers/staging/zsmalloc/zsmalloc_int.h | 1 +
5 files changed, 39 insertions(+), 18 deletions(-)
diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
index c9e08bb..a8aabbe 100644
--- a/drivers/staging/zcache/zcache-main.c
+++ b/drivers/staging/zcache/zcache-main.c
@@ -708,7 +708,7 @@ 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;
@@ -727,7 +727,7 @@ 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);
@@ -749,7 +749,7 @@ 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);
diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c
index 706cb62..653b074 100644
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -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);
diff --git a/drivers/staging/zsmalloc/zsmalloc-main.c b/drivers/staging/zsmalloc/zsmalloc-main.c
index abf7c13..8b0bcb6 100644
--- a/drivers/staging/zsmalloc/zsmalloc-main.c
+++ b/drivers/staging/zsmalloc/zsmalloc-main.c
@@ -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;
@@ -778,7 +773,11 @@ void *zs_map_object(struct zs_pool *pool, unsigned long handle)
return area->vm_addr + off;
}
- zs_copy_map_object(area->vm_buf, page, off, class->size);
+ /* 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);
+ /* single-page object fastpath */
if (area->vm_addr) {
- /* single-page object fastpath */
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);
diff --git a/drivers/staging/zsmalloc/zsmalloc.h b/drivers/staging/zsmalloc/zsmalloc.h
index 485cbb1..de2e8bf 100644
--- a/drivers/staging/zsmalloc/zsmalloc.h
+++ b/drivers/staging/zsmalloc/zsmalloc.h
@@ -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);
diff --git a/drivers/staging/zsmalloc/zsmalloc_int.h b/drivers/staging/zsmalloc/zsmalloc_int.h
index f760dae..52805176 100644
--- a/drivers/staging/zsmalloc/zsmalloc_int.h
+++ b/drivers/staging/zsmalloc/zsmalloc_int.h
@@ -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 {
--
1.7.9.5
--
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