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Commit 99944d1f authored Jun 07, 2013 by Jiang Liu Committed by Olav Haugan Oct 28, 2013

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.

Change-Id: Ic1e5f79328b998ec2d0b571851199dfd2d5560a6
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Git-commit: da5cc7d338f97886ebf35be92995460289379b73
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>

parent c7b621b8

drivers/staging/zram/zram_drv.c

+8 −29

Original line number	Diff line number	Diff line
		@@ -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) {

drivers/staging/zram/zram_drv.h

+11 −8

Original line number	Diff line number	Diff line
		@@ -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 */

drivers/staging/zram/zram_sysfs.c

+5 −16

Original line number	Diff line number	Diff line
		@@ -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,