From da5cc7d338f97886ebf35be92995460289379b73 Mon Sep 17 00:00:00 2001 From: Jiang Liu Date: Fri, 7 Jun 2013 00:07:31 +0800 Subject: [PATCH] zram: use atomic64_xxx() to replace zram_stat64_xxx() Use atomic64_xxx() to replace open-coded zram_stat64_xxx(). Some architectures have native support of atomic64 operations, so we can get rid of the spin_lock() in zram_stat64_xxx(). On the other hand, for platforms use generic version of atomic64 implement, it may cause an extra save/restore of the interrupt flag. So it's a tradeoff. Signed-off-by: Jiang Liu Signed-off-by: Greg Kroah-Hartman --- drivers/staging/zram/zram_drv.c | 37 ++++++++----------------------------- drivers/staging/zram/zram_drv.h | 19 +++++++++++-------- drivers/staging/zram/zram_sysfs.c | 21 +++++---------------- 3 files changed, 24 insertions(+), 53 deletions(-) diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c index 4b30fe5..ec2b2b5 100644 --- a/drivers/staging/zram/zram_drv.c +++ b/drivers/staging/zram/zram_drv.c @@ -42,25 +42,6 @@ static struct zram *zram_devices; /* Module params (documentation at end) */ static unsigned int num_devices = 1; -static void zram_stat64_add(struct zram *zram, u64 *v, u64 inc) -{ - spin_lock(&zram->stat64_lock); - *v = *v + inc; - spin_unlock(&zram->stat64_lock); -} - -static void zram_stat64_sub(struct zram *zram, u64 *v, u64 dec) -{ - spin_lock(&zram->stat64_lock); - *v = *v - dec; - spin_unlock(&zram->stat64_lock); -} - -static void zram_stat64_inc(struct zram *zram, u64 *v) -{ - zram_stat64_add(zram, v, 1); -} - static int zram_test_flag(struct zram_meta *meta, u32 index, enum zram_pageflags flag) { @@ -120,8 +101,7 @@ static void zram_free_page(struct zram *zram, size_t index) if (size <= PAGE_SIZE / 2) zram->stats.good_compress--; - zram_stat64_sub(zram, &zram->stats.compr_size, - meta->table[index].size); + atomic64_sub(meta->table[index].size, &zram->stats.compr_size); zram->stats.pages_stored--; meta->table[index].handle = 0; @@ -172,7 +152,7 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index) /* Should NEVER happen. Return bio error if it does. */ if (unlikely(ret != LZO_E_OK)) { pr_err("Decompression failed! err=%d, page=%u\n", ret, index); - zram_stat64_inc(zram, &zram->stats.failed_reads); + atomic64_inc(&zram->stats.failed_reads); return ret; } @@ -326,7 +306,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, meta->table[index].size = clen; /* Update stats */ - zram_stat64_add(zram, &zram->stats.compr_size, clen); + atomic64_add(clen, &zram->stats.compr_size); zram->stats.pages_stored++; if (clen <= PAGE_SIZE / 2) zram->stats.good_compress++; @@ -336,7 +316,7 @@ out: kfree(uncmem); if (ret) - zram_stat64_inc(zram, &zram->stats.failed_writes); + atomic64_inc(&zram->stats.failed_writes); return ret; } @@ -373,10 +353,10 @@ static void __zram_make_request(struct zram *zram, struct bio *bio, int rw) switch (rw) { case READ: - zram_stat64_inc(zram, &zram->stats.num_reads); + atomic64_inc(&zram->stats.num_reads); break; case WRITE: - zram_stat64_inc(zram, &zram->stats.num_writes); + atomic64_inc(&zram->stats.num_writes); break; } @@ -456,7 +436,7 @@ static void zram_make_request(struct request_queue *queue, struct bio *bio) goto error; if (!valid_io_request(zram, bio)) { - zram_stat64_inc(zram, &zram->stats.invalid_io); + atomic64_inc(&zram->stats.invalid_io); goto error; } @@ -595,7 +575,7 @@ static void zram_slot_free_notify(struct block_device *bdev, down_write(&zram->lock); zram_free_page(zram, index); up_write(&zram->lock); - zram_stat64_inc(zram, &zram->stats.notify_free); + atomic64_inc(&zram->stats.notify_free); } static const struct block_device_operations zram_devops = { @@ -609,7 +589,6 @@ static int create_device(struct zram *zram, int device_id) init_rwsem(&zram->lock); init_rwsem(&zram->init_lock); - spin_lock_init(&zram->stat64_lock); zram->queue = blk_alloc_queue(GFP_KERNEL); if (!zram->queue) { diff --git a/drivers/staging/zram/zram_drv.h b/drivers/staging/zram/zram_drv.h index b3a315d..11b09fc 100644 --- a/drivers/staging/zram/zram_drv.h +++ b/drivers/staging/zram/zram_drv.h @@ -69,14 +69,18 @@ struct table { u8 flags; } __aligned(4); +/* + * All 64bit fields should only be manipulated by 64bit atomic accessors. + * All modifications to 32bit counter should be protected by zram->lock. + */ struct zram_stats { - u64 compr_size; /* compressed size of pages stored */ - u64 num_reads; /* failed + successful */ - u64 num_writes; /* --do-- */ - u64 failed_reads; /* should NEVER! happen */ - u64 failed_writes; /* can happen when memory is too low */ - u64 invalid_io; /* non-page-aligned I/O requests */ - u64 notify_free; /* no. of swap slot free notifications */ + atomic64_t compr_size; /* compressed size of pages stored */ + atomic64_t num_reads; /* failed + successful */ + atomic64_t num_writes; /* --do-- */ + atomic64_t failed_reads; /* should NEVER! happen */ + 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 */ u32 pages_zero; /* no. of zero filled pages */ u32 pages_stored; /* no. of pages currently stored */ u32 good_compress; /* % of pages with compression ratio<=50% */ @@ -92,7 +96,6 @@ struct zram_meta { struct zram { struct zram_meta *meta; - spinlock_t stat64_lock; /* protect 64-bit stats */ struct rw_semaphore lock; /* protect compression buffers, table, * 32bit stat counters against concurrent * notifications, reads and writes */ diff --git a/drivers/staging/zram/zram_sysfs.c b/drivers/staging/zram/zram_sysfs.c index e239d94..93a2f9c 100644 --- a/drivers/staging/zram/zram_sysfs.c +++ b/drivers/staging/zram/zram_sysfs.c @@ -19,17 +19,6 @@ #include "zram_drv.h" -static u64 zram_stat64_read(struct zram *zram, u64 *v) -{ - u64 val; - - spin_lock(&zram->stat64_lock); - val = *v; - spin_unlock(&zram->stat64_lock); - - return val; -} - static inline struct zram *dev_to_zram(struct device *dev) { return (struct zram *)dev_to_disk(dev)->private_data; @@ -116,7 +105,7 @@ static ssize_t num_reads_show(struct device *dev, struct zram *zram = dev_to_zram(dev); return sprintf(buf, "%llu\n", - zram_stat64_read(zram, &zram->stats.num_reads)); + (u64)atomic64_read(&zram->stats.num_reads)); } static ssize_t num_writes_show(struct device *dev, @@ -125,7 +114,7 @@ static ssize_t num_writes_show(struct device *dev, struct zram *zram = dev_to_zram(dev); return sprintf(buf, "%llu\n", - zram_stat64_read(zram, &zram->stats.num_writes)); + (u64)atomic64_read(&zram->stats.num_writes)); } static ssize_t invalid_io_show(struct device *dev, @@ -134,7 +123,7 @@ static ssize_t invalid_io_show(struct device *dev, struct zram *zram = dev_to_zram(dev); return sprintf(buf, "%llu\n", - zram_stat64_read(zram, &zram->stats.invalid_io)); + (u64)atomic64_read(&zram->stats.invalid_io)); } static ssize_t notify_free_show(struct device *dev, @@ -143,7 +132,7 @@ static ssize_t notify_free_show(struct device *dev, struct zram *zram = dev_to_zram(dev); return sprintf(buf, "%llu\n", - zram_stat64_read(zram, &zram->stats.notify_free)); + (u64)atomic64_read(&zram->stats.notify_free)); } static ssize_t zero_pages_show(struct device *dev, @@ -169,7 +158,7 @@ static ssize_t compr_data_size_show(struct device *dev, struct zram *zram = dev_to_zram(dev); return sprintf(buf, "%llu\n", - zram_stat64_read(zram, &zram->stats.compr_size)); + (u64)atomic64_read(&zram->stats.compr_size)); } static ssize_t mem_used_total_show(struct device *dev, -- 2.7.4