| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <1483510806-12890-1-git-send-email-zhouxianrong@huawei.com>
Date: Wed, 4 Jan 2017 14:20:05 +0800
From: <zhouxianrong@...wei.com>
To: unlisted-recipients:; (no To-header on input)
CC: <linux-kernel@...r.kernel.org>, <minchan@...nel.org>,
<ngupta@...are.org>, <zhouxianrong@...wei.com>,
<zhouxiyu@...wei.com>, <weidu.du@...wei.com>,
<zhangshiming5@...wei.com>, <won.ho.park@...wei.com>
Subject: [PATCH zram] extend zero pages to same element pages
From: z00281421 <z00281421@...esmail.huawei.com>
Signed-off-by: z00281421 <z00281421@...esmail.huawei.com>
---
drivers/block/zram/zram_drv.c | 67 ++++++++++++++++++++++++++---------------
drivers/block/zram/zram_drv.h | 11 ++++---
2 files changed, 49 insertions(+), 29 deletions(-)
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 15f58ab..c3af69a 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -94,6 +94,17 @@ static void zram_clear_flag(struct zram_meta *meta, u32 index,
meta->table[index].value &= ~BIT(flag);
}
+static inline void zram_set_element(struct zram_meta *meta, u32 index,
+ unsigned long element)
+{
+ meta->table[index].element = element;
+}
+
+static inline void zram_clear_element(struct zram_meta *meta, u32 index)
+{
+ meta->table[index].element = 0;
+}
+
static size_t zram_get_obj_size(struct zram_meta *meta, u32 index)
{
return meta->table[index].value & (BIT(ZRAM_FLAG_SHIFT) - 1);
@@ -158,31 +169,31 @@ static inline void update_used_max(struct zram *zram,
} while (old_max != cur_max);
}
-static bool page_zero_filled(void *ptr)
+static bool page_same_filled(void *ptr)
{
unsigned int pos;
unsigned long *page;
page = (unsigned long *)ptr;
- for (pos = 0; pos != PAGE_SIZE / sizeof(*page); pos++) {
- if (page[pos])
+ for (pos = PAGE_SIZE / sizeof(unsigned long) - 1; pos > 0; pos--) {
+ if (page[pos] != page[pos - 1])
return false;
}
return true;
}
-static void handle_zero_page(struct bio_vec *bvec)
+static void handle_same_page(struct bio_vec *bvec, unsigned long element)
{
struct page *page = bvec->bv_page;
void *user_mem;
user_mem = kmap_atomic(page);
if (is_partial_io(bvec))
- memset(user_mem + bvec->bv_offset, 0, bvec->bv_len);
+ memset(user_mem + bvec->bv_offset, (char)element, bvec->bv_len);
else
- clear_page(user_mem);
+ memset(user_mem, (char)element, PAGE_SIZE);
kunmap_atomic(user_mem);
flush_dcache_page(page);
@@ -431,7 +442,7 @@ static ssize_t mm_stat_show(struct device *dev,
mem_used << PAGE_SHIFT,
zram->limit_pages << PAGE_SHIFT,
max_used << PAGE_SHIFT,
- (u64)atomic64_read(&zram->stats.zero_pages),
+ (u64)atomic64_read(&zram->stats.same_pages),
pool_stats.pages_compacted);
up_read(&zram->init_lock);
@@ -464,7 +475,7 @@ static ssize_t debug_stat_show(struct device *dev,
ZRAM_ATTR_RO(failed_writes);
ZRAM_ATTR_RO(invalid_io);
ZRAM_ATTR_RO(notify_free);
-ZRAM_ATTR_RO(zero_pages);
+ZRAM_ATTR_RO(same_pages);
ZRAM_ATTR_RO(compr_data_size);
static inline bool zram_meta_get(struct zram *zram)
@@ -538,18 +549,20 @@ static void zram_free_page(struct zram *zram, size_t index)
struct zram_meta *meta = zram->meta;
unsigned long handle = meta->table[index].handle;
- if (unlikely(!handle)) {
- /*
- * No memory is allocated for zero filled pages.
- * Simply clear zero page flag.
- */
- if (zram_test_flag(meta, index, ZRAM_ZERO)) {
- zram_clear_flag(meta, index, ZRAM_ZERO);
- atomic64_dec(&zram->stats.zero_pages);
- }
+ /*
+ * No memory is allocated for same element filled pages.
+ * Simply clear same page flag.
+ */
+ if (zram_test_flag(meta, index, ZRAM_SAME)) {
+ zram_clear_flag(meta, index, ZRAM_SAME);
+ zram_clear_element(meta, index);
+ atomic64_dec(&zram->stats.same_pages);
return;
}
+ if (!handle)
+ return;
+
zs_free(meta->mem_pool, handle);
atomic64_sub(zram_get_obj_size(meta, index),
@@ -572,9 +585,9 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
handle = meta->table[index].handle;
size = zram_get_obj_size(meta, index);
- if (!handle || zram_test_flag(meta, index, ZRAM_ZERO)) {
+ if (!handle || zram_test_flag(meta, index, ZRAM_SAME)) {
bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
- clear_page(mem);
+ memset(mem, (char)meta->table[index].element, PAGE_SIZE);
return 0;
}
@@ -610,9 +623,9 @@ static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
if (unlikely(!meta->table[index].handle) ||
- zram_test_flag(meta, index, ZRAM_ZERO)) {
+ zram_test_flag(meta, index, ZRAM_SAME)) {
bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
- handle_zero_page(bvec);
+ handle_same_page(bvec, meta->table[index].element);
return 0;
}
bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
@@ -688,16 +701,20 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
uncmem = user_mem;
}
- if (page_zero_filled(uncmem)) {
+ if (page_same_filled(uncmem)) {
+ unsigned long element;
+
+ element = uncmem[0];
if (user_mem)
kunmap_atomic(user_mem);
/* Free memory associated with this sector now. */
bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
zram_free_page(zram, index);
- zram_set_flag(meta, index, ZRAM_ZERO);
+ zram_set_flag(meta, index, ZRAM_SAME);
+ zram_set_element(meta, index, element);
bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
- atomic64_inc(&zram->stats.zero_pages);
+ atomic64_inc(&zram->stats.same_pages);
ret = 0;
goto out;
}
@@ -1203,7 +1220,7 @@ static int zram_open(struct block_device *bdev, fmode_t mode)
&dev_attr_compact.attr,
&dev_attr_invalid_io.attr,
&dev_attr_notify_free.attr,
- &dev_attr_zero_pages.attr,
+ &dev_attr_same_pages.attr,
&dev_attr_orig_data_size.attr,
&dev_attr_compr_data_size.attr,
&dev_attr_mem_used_total.attr,
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 74fcf10..4bb92e1 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -60,8 +60,8 @@
/* Flags for zram pages (table[page_no].value) */
enum zram_pageflags {
- /* Page consists entirely of zeros */
- ZRAM_ZERO = ZRAM_FLAG_SHIFT,
+ /* Page consists entirely of same elements */
+ ZRAM_SAME = ZRAM_FLAG_SHIFT,
ZRAM_ACCESS, /* page is now accessed */
__NR_ZRAM_PAGEFLAGS,
@@ -71,7 +71,10 @@ enum zram_pageflags {
/* Allocated for each disk page */
struct zram_table_entry {
- unsigned long handle;
+ union {
+ unsigned long handle;
+ unsigned long element;
+ };
unsigned long value;
};
@@ -83,7 +86,7 @@ struct zram_stats {
atomic64_t failed_writes; /* can happen when memory is too low */
atomic64_t invalid_io; /* non-page-aligned I/O requests */
atomic64_t notify_free; /* no. of swap slot free notifications */
- atomic64_t zero_pages; /* no. of zero filled pages */
+ atomic64_t same_pages; /* no. of same element filled pages */
atomic64_t pages_stored; /* no. of pages currently stored */
atomic_long_t max_used_pages; /* no. of maximum pages stored */
atomic64_t writestall; /* no. of write slow paths */
--
1.7.9.5
Powered by blists - more mailing lists