When CONFIG_MMC_BLOCK_MAX_SPEED is enabled, Expose max_read_speed, max_write_speed and cache_size controls to simulate a slow eMMC device. The boot default values for each respectively are CONFIG_MMC_BLOCK_MAX_READ_SPEED, CONFIG_MMC_BLOCK_MAX_WRITE_SPEED and CONFIG_MMC_BLOCK_CACHE_SIZE respectively; and if not defined are 0 (off), 0, (off) and 4 MB also respectively.
Signed-off-by: Mark Salyzyn <[email protected]> --- drivers/mmc/card/Kconfig | 54 +++++++++ drivers/mmc/card/block.c | 295 +++++++++++++++++++++++++++++++++++++++++++++++ drivers/mmc/card/queue.h | 8 ++ 3 files changed, 357 insertions(+) diff --git a/drivers/mmc/card/Kconfig b/drivers/mmc/card/Kconfig index 5562308..70bf39c 100644 --- a/drivers/mmc/card/Kconfig +++ b/drivers/mmc/card/Kconfig @@ -68,3 +68,57 @@ config MMC_TEST This driver is only of interest to those developing or testing a host driver. Most people should say N here. + +config MMC_BLOCK_MAX_SPEED + bool "Turn on maximum speed control per block device" + depends on MMC_BLOCK + help + Say Y here to enable MMC device speed limiting. Used to test and + simulate the behavior of the system when confronted with a slow MMC. + + Enables max_read_speed and max_write_speed attributes to control the + write or read maximum KB/second speed. + + If unsure, say N here. + +config MMC_BLOCK_MAX_READ_SPEED + int "KB/second read speed limit per block device" + depends on MMC_BLOCK + depends on MMC_BLOCK_MAX_SPEED + default 0 + help + Number of KB/second reads allowed to the block device. Used to + test and simulate the behavior of the system when confronted with + a slow MMC. + + Value can be overridden at runtime with the max_read_speed attribute. + + If unsure, say 0 here (no speed limit) + +config MMC_BLOCK_MAX_WRITE_SPEED + int "KB/second write speed limit per block device" + depends on MMC_BLOCK + depends on MMC_BLOCK_MAX_SPEED + default 0 + help + Number of KB/second writes allowed to the block device. Used to + test and simulate the behavior of the system when confronted with + a slow MMC. + + Value can be overridden at runtime with the max_write_speed attribute. + + If unsure, say 0 here (no speed limit) + +config MMC_BLOCK_MAX_SPEED_CACHE_SIZE + int "MB of memory or SLC cache" + depends on MMC_BLOCK + depends on MMC_BLOCK_MAX_SPEED + default 4 + help + Number of MB of high speed memory or SLC cache expected on the + eMMC device. Used to help simulate the write-back behavior more + accurately. + + Value can be overridden at runtime with the cache_size attribute. + + If unsure, say 4 here diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c index 5914263..b2075bf 100644 --- a/drivers/mmc/card/block.c +++ b/drivers/mmc/card/block.c @@ -289,6 +289,242 @@ out: return ret; } +#ifdef CONFIG_MMC_BLOCK_MAX_SPEED + +/* + * helper macros and expectations: + * size - unsigned long number of bytes + * jiffies - unsigned long HZ timestamp difference + * speed - unsigned KB/s transfer rate + */ +#define size_and_speed_to_jiffies(size, speed) \ + ((size) * HZ / (speed) / 1024UL) +#define jiffies_and_speed_to_size(jiffies, speed) \ + (((speed) * (jiffies) * 1024UL) / HZ) +#define jiffies_and_size_to_speed(jiffies, size) \ + ((size) * HZ / (jiffies) / 1024UL) + +/* Limits to report warning */ +/* jiffies_and_size_to_speed(10*HZ, queue_max_hw_sectors(q) * 512UL) ~ 25 */ +#define MIN_SPEED(q) 250 /* 10 times faster than a floppy disk */ +#define MAX_SPEED(q) jiffies_and_size_to_speed(1, queue_max_sectors(q) * 512UL) + +#define speed_valid(speed) ((speed) > 0) + +static const char off[] = "off\n"; + +static int max_speed_show(int speed, char *buf) +{ + if (speed) + return scnprintf(buf, PAGE_SIZE, "%uKB/s\n", speed); + else + return scnprintf(buf, PAGE_SIZE, off); +} + +static int max_speed_store(const char *buf, struct request_queue *q) +{ + long set = 0; + unsigned limit; + + if (!strncasecmp(off, buf, sizeof(off) - 2)) + return set; + if (kstrtol(buf, 0, &set) || (set < 0) || (set > INT_MAX)) + return -EINVAL; + if (set == 0) + return set; + limit = MAX_SPEED(q); + if (set > limit) + pr_warn("max speed %ld ineffective above %u\n", set, limit); + limit = MIN_SPEED(q); + if (set < limit) + pr_warn("max speed %ld painful below %u\n", set, limit); + return set; +} + +static ssize_t max_write_speed_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct mmc_blk_data *md = mmc_blk_get(dev_to_disk(dev)); + int ret = max_speed_show(atomic_read(&md->queue.max_write_speed), buf); + + mmc_blk_put(md); + return ret; +} + +static ssize_t max_write_speed_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct mmc_blk_data *md = mmc_blk_get(dev_to_disk(dev)); + int set = max_speed_store(buf, md->queue.queue); + + if (set < 0) { + mmc_blk_put(md); + return set; + } + + atomic_set(&md->queue.max_write_speed, set); + mmc_blk_put(md); + return count; +} + +static const DEVICE_ATTR(max_write_speed, S_IRUGO | S_IWUSR, + max_write_speed_show, max_write_speed_store); + +static ssize_t max_read_speed_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct mmc_blk_data *md = mmc_blk_get(dev_to_disk(dev)); + int ret = max_speed_show(atomic_read(&md->queue.max_read_speed), buf); + + mmc_blk_put(md); + return ret; +} + +static ssize_t max_read_speed_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct mmc_blk_data *md = mmc_blk_get(dev_to_disk(dev)); + int set = max_speed_store(buf, md->queue.queue); + + if (set < 0) { + mmc_blk_put(md); + return set; + } + + atomic_set(&md->queue.max_read_speed, set); + mmc_blk_put(md); + return count; +} + +static const DEVICE_ATTR(max_read_speed, S_IRUGO | S_IWUSR, + max_read_speed_show, max_read_speed_store); + +static ssize_t cache_size_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct mmc_blk_data *md = mmc_blk_get(dev_to_disk(dev)); + struct mmc_queue *mq = &md->queue; + int cache_size = atomic_read(&mq->cache_size); + int ret; + + if (!cache_size) + ret = scnprintf(buf, PAGE_SIZE, off); + else { + int speed = atomic_read(&mq->max_write_speed); + + if (!speed_valid(speed)) + ret = scnprintf(buf, PAGE_SIZE, "%uMB\n", cache_size); + else { /* We accept race between cache_jiffies and cache_used */ + unsigned long size = jiffies_and_speed_to_size( + jiffies - mq->cache_jiffies, speed); + long used = atomic_long_read(&mq->cache_used); + + if (size >= used) + size = 0; + else + size = (used - size) * 100 / cache_size + / 1024UL / 1024UL; + + ret = scnprintf(buf, PAGE_SIZE, "%uMB %lu%% used\n", + cache_size, size); + } + } + + mmc_blk_put(md); + return ret; +} + +static ssize_t cache_size_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t count) +{ + struct mmc_blk_data *md; + long set = 0; + + if (strncasecmp(off, buf, sizeof(off) - 2) + && (kstrtol(buf, 0, &set) || (set < 0) || (set > INT_MAX))) + return -EINVAL; + + md = mmc_blk_get(dev_to_disk(dev)); + atomic_set(&md->queue.cache_size, set); + mmc_blk_put(md); + return count; +} + +static const DEVICE_ATTR(cache_size, S_IRUGO | S_IWUSR, + cache_size_show, cache_size_store); + +/* correct for write-back */ +static long mmc_blk_cache_used(struct mmc_queue *mq, unsigned long waitfor) +{ + long used = 0; + int speed = atomic_read(&mq->max_write_speed); + + if (speed_valid(speed)) { + unsigned long size = jiffies_and_speed_to_size( + waitfor - mq->cache_jiffies, speed); + used = atomic_long_read(&mq->cache_used); + + if (size >= used) + used = 0; + else + used -= size; + } + + atomic_long_set(&mq->cache_used, used); + mq->cache_jiffies = waitfor; + + return used; +} + +static void mmc_blk_waitfor_completion( + struct mmc_queue *mq, + struct request *req, + unsigned long waitfor) +{ + int max_speed; + + if (!req) + return; + + max_speed = (rq_data_dir(req) == READ) + ? atomic_read(&mq->max_read_speed) + : atomic_read(&mq->max_write_speed); + if (speed_valid(max_speed)) { + unsigned long bytes = blk_rq_bytes(req); + + if (rq_data_dir(req) != READ) { + int cache_size = atomic_read(&mq->cache_size); + + if (cache_size) { + unsigned long size = cache_size * 1024L * 1024L; + long used = mmc_blk_cache_used(mq, waitfor); + + used += bytes; + atomic_long_set(&mq->cache_used, used); + bytes = 0; + if (used > size) + bytes = used - size; + } + } + waitfor += size_and_speed_to_jiffies(bytes, max_speed); + if (time_is_after_jiffies(waitfor)) { + unsigned long msecs = jiffies_to_msecs( + waitfor - jiffies); + if (msecs) + msleep(msecs); + } + } +} + +#else + +#define mmc_blk_waitfor_completion(mq, req, waitfor) + +#endif + static int mmc_blk_open(struct block_device *bdev, fmode_t mode) { struct mmc_blk_data *md = mmc_blk_get(bdev->bd_disk); @@ -1251,6 +1487,23 @@ static int mmc_blk_issue_flush(struct mmc_queue *mq, struct request *req) if (ret) ret = -EIO; +#ifdef CONFIG_MMC_BLOCK_MAX_SPEED + else if (atomic_read(&mq->cache_size)) { + long used = mmc_blk_cache_used(mq, jiffies); + + if (used) { + int speed = atomic_read(&mq->max_write_speed); + + if (speed_valid(speed)) { + unsigned long msecs = jiffies_to_msecs( + size_and_speed_to_jiffies( + used, speed)); + if (msecs) + msleep(msecs); + } + } + } +#endif blk_end_request_all(req, ret); return ret ? 0 : 1; @@ -1930,6 +2183,9 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *rqc) struct mmc_async_req *areq; const u8 packed_nr = 2; u8 reqs = 0; +#ifdef CONFIG_MMC_BLOCK_MAX_SPEED + unsigned long waitfor = jiffies; +#endif if (!rqc && !mq->mqrq_prev->req) return 0; @@ -1980,6 +2236,8 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *rqc) */ mmc_blk_reset_success(md, type); + mmc_blk_waitfor_completion(mq, rqc, waitfor); + if (mmc_packed_cmd(mq_rq->cmd_type)) { ret = mmc_blk_end_packed_req(mq_rq); break; @@ -2398,6 +2656,14 @@ static void mmc_blk_remove_req(struct mmc_blk_data *md) card->ext_csd.boot_ro_lockable) device_remove_file(disk_to_dev(md->disk), &md->power_ro_lock); +#ifdef CONFIG_MMC_BLOCK_MAX_SPEED + device_remove_file(disk_to_dev(md->disk), + &dev_attr_max_write_speed); + device_remove_file(disk_to_dev(md->disk), + &dev_attr_max_read_speed); + device_remove_file(disk_to_dev(md->disk), + &dev_attr_cache_size); +#endif del_gendisk(md->disk); } @@ -2433,6 +2699,27 @@ static int mmc_add_disk(struct mmc_blk_data *md) ret = device_create_file(disk_to_dev(md->disk), &md->force_ro); if (ret) goto force_ro_fail; +#ifdef CONFIG_MMC_BLOCK_MAX_SPEED + atomic_set(&md->queue.max_write_speed, + CONFIG_MMC_BLOCK_MAX_WRITE_SPEED); + ret = device_create_file(disk_to_dev(md->disk), + &dev_attr_max_write_speed); + if (ret) + goto max_write_speed_fail; + atomic_set(&md->queue.max_read_speed, + CONFIG_MMC_BLOCK_MAX_READ_SPEED); + ret = device_create_file(disk_to_dev(md->disk), + &dev_attr_max_read_speed); + if (ret) + goto max_read_speed_fail; + atomic_set(&md->queue.cache_size, + CONFIG_MMC_BLOCK_MAX_SPEED_CACHE_SIZE); + atomic_long_set(&md->queue.cache_used, 0); + md->queue.cache_jiffies = jiffies; + ret = device_create_file(disk_to_dev(md->disk), &dev_attr_cache_size); + if (ret) + goto cache_size_fail; +#endif if ((md->area_type & MMC_BLK_DATA_AREA_BOOT) && card->ext_csd.boot_ro_lockable) { @@ -2457,6 +2744,14 @@ static int mmc_add_disk(struct mmc_blk_data *md) return ret; power_ro_lock_fail: +#ifdef CONFIG_MMC_BLOCK_MAX_SPEED + device_remove_file(disk_to_dev(md->disk), &dev_attr_cache_size); +cache_size_fail: + device_remove_file(disk_to_dev(md->disk), &dev_attr_max_read_speed); +max_read_speed_fail: + device_remove_file(disk_to_dev(md->disk), &dev_attr_max_write_speed); +max_write_speed_fail: +#endif device_remove_file(disk_to_dev(md->disk), &md->force_ro); force_ro_fail: del_gendisk(md->disk); diff --git a/drivers/mmc/card/queue.h b/drivers/mmc/card/queue.h index 36cddab..fd7cef8 100644 --- a/drivers/mmc/card/queue.h +++ b/drivers/mmc/card/queue.h @@ -58,6 +58,14 @@ struct mmc_queue { struct mmc_queue_req mqrq[2]; struct mmc_queue_req *mqrq_cur; struct mmc_queue_req *mqrq_prev; +#ifdef CONFIG_MMC_BLOCK_MAX_SPEED + atomic_t max_write_speed; + atomic_t max_read_speed; + atomic_t cache_size; + /* i/o tracking */ + atomic_long_t cache_used; + unsigned long cache_jiffies; +#endif }; extern int mmc_init_queue(struct mmc_queue *, struct mmc_card *, spinlock_t *, -- 2.7.0.rc3.207.g0ac5344
