diff options
Diffstat (limited to 'block')
| -rw-r--r-- | block/Kconfig | 12 | ||||
| -rw-r--r-- | block/Makefile | 2 | ||||
| -rw-r--r-- | block/blktrace.c | 538 | ||||
| -rw-r--r-- | block/elevator.c | 4 | ||||
| -rw-r--r-- | block/ioctl.c | 6 | ||||
| -rw-r--r-- | block/ll_rw_blk.c | 44 |
6 files changed, 604 insertions, 2 deletions
diff --git a/block/Kconfig b/block/Kconfig index 377f6dd20e1..96783645092 100644 --- a/block/Kconfig +++ b/block/Kconfig @@ -11,4 +11,16 @@ config LBD your machine, or if you want to have a raid or loopback device bigger than 2TB. Otherwise say N. +config BLK_DEV_IO_TRACE + bool "Support for tracing block io actions" + select RELAY + select DEBUG_FS + help + Say Y here, if you want to be able to trace the block layer actions + on a given queue. Tracing allows you to see any traffic happening + on a block device queue. For more information (and the user space + support tools needed), fetch the blktrace app from: + + git://brick.kernel.dk/data/git/blktrace.git + source block/Kconfig.iosched diff --git a/block/Makefile b/block/Makefile index 7e4f93e2b44..c05de0e0037 100644 --- a/block/Makefile +++ b/block/Makefile @@ -8,3 +8,5 @@ obj-$(CONFIG_IOSCHED_NOOP) += noop-iosched.o obj-$(CONFIG_IOSCHED_AS) += as-iosched.o obj-$(CONFIG_IOSCHED_DEADLINE) += deadline-iosched.o obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o + +obj-$(CONFIG_BLK_DEV_IO_TRACE) += blktrace.o diff --git a/block/blktrace.c b/block/blktrace.c new file mode 100644 index 00000000000..36f3a172275 --- /dev/null +++ b/block/blktrace.c @@ -0,0 +1,538 @@ +/* + * Copyright (C) 2006 Jens Axboe <axboe@suse.de> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + * + */ +#include <linux/config.h> +#include <linux/kernel.h> +#include <linux/blkdev.h> +#include <linux/blktrace_api.h> +#include <linux/percpu.h> +#include <linux/init.h> +#include <linux/mutex.h> +#include <linux/debugfs.h> +#include <asm/uaccess.h> + +static DEFINE_PER_CPU(unsigned long long, blk_trace_cpu_offset) = { 0, }; +static unsigned int blktrace_seq __read_mostly = 1; + +/* + * Send out a notify for this process, if we haven't done so since a trace + * started + */ +static void trace_note_tsk(struct blk_trace *bt, struct task_struct *tsk) +{ + struct blk_io_trace *t; + + t = relay_reserve(bt->rchan, sizeof(*t) + sizeof(tsk->comm)); + if (t) { + t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION; + t->device = bt->dev; + t->action = BLK_TC_ACT(BLK_TC_NOTIFY); + t->pid = tsk->pid; + t->cpu = smp_processor_id(); + t->pdu_len = sizeof(tsk->comm); + memcpy((void *) t + sizeof(*t), tsk->comm, t->pdu_len); + tsk->btrace_seq = blktrace_seq; + } +} + +static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector, + pid_t pid) +{ + if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0) + return 1; + if (sector < bt->start_lba || sector > bt->end_lba) + return 1; + if (bt->pid && pid != bt->pid) + return 1; + + return 0; +} + +/* + * Data direction bit lookup + */ +static u32 ddir_act[2] __read_mostly = { BLK_TC_ACT(BLK_TC_READ), BLK_TC_ACT(BLK_TC_WRITE) }; + +/* + * Bio action bits of interest + */ +static u32 bio_act[3] __read_mostly = { 0, BLK_TC_ACT(BLK_TC_BARRIER), BLK_TC_ACT(BLK_TC_SYNC) }; + +/* + * More could be added as needed, taking care to increment the decrementer + * to get correct indexing + */ +#define trace_barrier_bit(rw) \ + (((rw) & (1 << BIO_RW_BARRIER)) >> (BIO_RW_BARRIER - 0)) +#define trace_sync_bit(rw) \ + (((rw) & (1 << BIO_RW_SYNC)) >> (BIO_RW_SYNC - 1)) + +/* + * The worker for the various blk_add_trace*() types. Fills out a + * blk_io_trace structure and places it in a per-cpu subbuffer. + */ +void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes, + int rw, u32 what, int error, int pdu_len, void *pdu_data) +{ + struct task_struct *tsk = current; + struct blk_io_trace *t; + unsigned long flags; + unsigned long *sequence; + pid_t pid; + int cpu; + + if (unlikely(bt->trace_state != Blktrace_running)) + return; + + what |= ddir_act[rw & WRITE]; + what |= bio_act[trace_barrier_bit(rw)]; + what |= bio_act[trace_sync_bit(rw)]; + + pid = tsk->pid; + if (unlikely(act_log_check(bt, what, sector, pid))) + return; + + /* + * A word about the locking here - we disable interrupts to reserve + * some space in the relay per-cpu buffer, to prevent an irq + * from coming in and stepping on our toes. Once reserved, it's + * enough to get preemption disabled to prevent read of this data + * before we are through filling it. get_cpu()/put_cpu() does this + * for us + */ + local_irq_save(flags); + + if (unlikely(tsk->btrace_seq != blktrace_seq)) + trace_note_tsk(bt, tsk); + + t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len); + if (t) { + cpu = smp_processor_id(); + sequence = per_cpu_ptr(bt->sequence, cpu); + + t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION; + t->sequence = ++(*sequence); + t->time = sched_clock() - per_cpu(blk_trace_cpu_offset, cpu); + t->sector = sector; + t->bytes = bytes; + t->action = what; + t->pid = pid; + t->device = bt->dev; + t->cpu = cpu; + t->error = error; + t->pdu_len = pdu_len; + + if (pdu_len) + memcpy((void *) t + sizeof(*t), pdu_data, pdu_len); + } + + local_irq_restore(flags); +} + +EXPORT_SYMBOL_GPL(__blk_add_trace); + +static struct dentry *blk_tree_root; +static struct mutex blk_tree_mutex; +static unsigned int root_users; + +static inline void blk_remove_root(void) +{ + if (blk_tree_root) { + debugfs_remove(blk_tree_root); + blk_tree_root = NULL; + } +} + +static void blk_remove_tree(struct dentry *dir) +{ + mutex_lock(&blk_tree_mutex); + debugfs_remove(dir); + if (--root_users == 0) + blk_remove_root(); + mutex_unlock(&blk_tree_mutex); +} + +static struct dentry *blk_create_tree(const char *blk_name) +{ + struct dentry *dir = NULL; + + mutex_lock(&blk_tree_mutex); + + if (!blk_tree_root) { + blk_tree_root = debugfs_create_dir("block", NULL); + if (!blk_tree_root) + goto err; + } + + dir = debugfs_create_dir(blk_name, blk_tree_root); + if (dir) + root_users++; + else + blk_remove_root(); + +err: + mutex_unlock(&blk_tree_mutex); + return dir; +} + +static void blk_trace_cleanup(struct blk_trace *bt) +{ + relay_close(bt->rchan); + debugfs_remove(bt->dropped_file); + blk_remove_tree(bt->dir); + free_percpu(bt->sequence); + kfree(bt); +} + +static int blk_trace_remove(request_queue_t *q) +{ + struct blk_trace *bt; + + bt = xchg(&q->blk_trace, NULL); + if (!bt) + return -EINVAL; + + if (bt->trace_state == Blktrace_setup || + bt->trace_state == Blktrace_stopped) + blk_trace_cleanup(bt); + + return 0; +} + +static int blk_dropped_open(struct inode *inode, struct file *filp) +{ + filp->private_data = inode->u.generic_ip; + + return 0; +} + +static ssize_t blk_dropped_read(struct file *filp, char __user *buffer, + size_t count, loff_t *ppos) +{ + struct blk_trace *bt = filp->private_data; + char buf[16]; + + snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped)); + + return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf)); +} + +static struct file_operations blk_dropped_fops = { + .owner = THIS_MODULE, + .open = blk_dropped_open, + .read = blk_dropped_read, +}; + +/* + * Keep track of how many times we encountered a full subbuffer, to aid + * the user space app in telling how many lost events there were. + */ +static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf, + void *prev_subbuf, size_t prev_padding) +{ + struct blk_trace *bt; + + if (!relay_buf_full(buf)) + return 1; + + bt = buf->chan->private_data; + atomic_inc(&bt->dropped); + return 0; +} + +static int blk_remove_buf_file_callback(struct dentry *dentry) +{ + debugfs_remove(dentry); + return 0; +} + +static struct dentry *blk_create_buf_file_callback(const char *filename, + struct dentry *parent, + int mode, + struct rchan_buf *buf, + int *is_global) +{ + return debugfs_create_file(filename, mode, parent, buf, + &relay_file_operations); +} + +static struct rchan_callbacks blk_relay_callbacks = { + .subbuf_start = blk_subbuf_start_callback, + .create_buf_file = blk_create_buf_file_callback, + .remove_buf_file = blk_remove_buf_file_callback, +}; + +/* + * Setup everything required to start tracing + */ +static int blk_trace_setup(request_queue_t *q, struct block_device *bdev, + char __user *arg) +{ + struct blk_user_trace_setup buts; + struct blk_trace *old_bt, *bt = NULL; + struct dentry *dir = NULL; + char b[BDEVNAME_SIZE]; + int ret, i; + + if (copy_from_user(&buts, arg, sizeof(buts))) + return -EFAULT; + + if (!buts.buf_size || !buts.buf_nr) + return -EINVAL; + + strcpy(buts.name, bdevname(bdev, b)); + + /* + * some device names have larger paths - convert the slashes + * to underscores for this to work as expected + */ + for (i = 0; i < strlen(buts.name); i++) + if (buts.name[i] == '/') + buts.name[i] = '_'; + + if (copy_to_user(arg, &buts, sizeof(buts))) + return -EFAULT; + + ret = -ENOMEM; + bt = kzalloc(sizeof(*bt), GFP_KERNEL); + if (!bt) + goto err; + + bt->sequence = alloc_percpu(unsigned long); + if (!bt->sequence) + goto err; + + ret = -ENOENT; + dir = blk_create_tree(buts.name); + if (!dir) + goto err; + + bt->dir = dir; + bt->dev = bdev->bd_dev; + atomic_set(&bt->dropped, 0); + + ret = -EIO; + bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt, &blk_dropped_fops); + if (!bt->dropped_file) + goto err; + + bt->rchan = relay_open("trace", dir, buts.buf_size, buts.buf_nr, &blk_relay_callbacks); + if (!bt->rchan) + goto err; + bt->rchan->private_data = bt; + + bt->act_mask = buts.act_mask; + if (!bt->act_mask) + bt->act_mask = (u16) -1; + + bt->start_lba = buts.start_lba; + bt->end_lba = buts.end_lba; + if (!bt->end_lba) + bt->end_lba = -1ULL; + + bt->pid = buts.pid; + bt->trace_state = Blktrace_setup; + + ret = -EBUSY; + old_bt = xchg(&q->blk_trace, bt); + if (old_bt) { + (void) xchg(&q->blk_trace, old_bt); + goto err; + } + + return 0; +err: + if (dir) + blk_remove_tree(dir); + if (bt) { + if (bt->dropped_file) + debugfs_remove(bt->dropped_file); + if (bt->sequence) + free_percpu(bt->sequence); + if (bt->rchan) + relay_close(bt->rchan); + kfree(bt); + } + return ret; +} + +static int blk_trace_startstop(request_queue_t *q, int start) +{ + struct blk_trace *bt; + int ret; + + if ((bt = q->blk_trace) == NULL) + return -EINVAL; + + /* + * For starting a trace, we can transition from a setup or stopped + * trace. For stopping a trace, the state must be running + */ + ret = -EINVAL; + if (start) { + if (bt->trace_state == Blktrace_setup || + bt->trace_state == Blktrace_stopped) { + blktrace_seq++; + smp_mb(); + bt->trace_state = Blktrace_running; + ret = 0; + } + } else { + if (bt->trace_state == Blktrace_running) { + bt->trace_state = Blktrace_stopped; + relay_flush(bt->rchan); + ret = 0; + } + } + + return ret; +} + +/** + * blk_trace_ioctl: - handle the ioctls associated with tracing + * @bdev: the block device + * @cmd: the ioctl cmd + * @arg: the argument data, if any + * + **/ +int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg) +{ + request_queue_t *q; + int ret, start = 0; + + q = bdev_get_queue(bdev); + if (!q) + return -ENXIO; + + mutex_lock(&bdev->bd_mutex); + + switch (cmd) { + case BLKTRACESETUP: + ret = blk_trace_setup(q, bdev, arg); + break; + case BLKTRACESTART: + start = 1; + case BLKTRACESTOP: + ret = blk_trace_startstop(q, start); + break; + case BLKTRACETEARDOWN: + ret = blk_trace_remove(q); + break; + default: + ret = -ENOTTY; + break; + } + + mutex_unlock(&bdev->bd_mutex); + return ret; +} + +/** + * blk_trace_shutdown: - stop and cleanup trace structures + * @q: the request queue associated with the device + * + **/ +void blk_trace_shutdown(request_queue_t *q) +{ + blk_trace_startstop(q, 0); + blk_trace_remove(q); +} + +/* + * Average offset over two calls to sched_clock() with a gettimeofday() + * in the middle + */ +static void blk_check_time(unsigned long long *t) +{ + unsigned long long a, b; + struct timeval tv; + + a = sched_clock(); + do_gettimeofday(&tv); + b = sched_clock(); + + *t = tv.tv_sec * 1000000000 + tv.tv_usec * 1000; + *t -= (a + b) / 2; +} + +static void blk_trace_check_cpu_time(void *data) +{ + unsigned long long *t; + int cpu = get_cpu(); + + t = &per_cpu(blk_trace_cpu_offset, cpu); + + /* + * Just call it twice, hopefully the second call will be cache hot + * and a little more precise + */ + blk_check_time(t); + blk_check_time(t); + + put_cpu(); +} + +/* + * Call blk_trace_check_cpu_time() on each CPU to calibrate our inter-CPU + * timings + */ +static void blk_trace_calibrate_offsets(void) +{ + unsigned long flags; + + smp_call_function(blk_trace_check_cpu_time, NULL, 1, 1); + local_irq_save(flags); + blk_trace_check_cpu_time(NULL); + local_irq_restore(flags); +} + +static void blk_trace_set_ht_offsets(void) +{ +#if defined(CONFIG_SCHED_SMT) + int cpu, i; + + /* + * now make sure HT siblings have the same time offset + */ + preempt_disable(); + for_each_online_cpu(cpu) { + unsigned long long *cpu_off, *sibling_off; + + for_each_cpu_mask(i, cpu_sibling_map[cpu]) { + if (i == cpu) + continue; + + cpu_off = &per_cpu(blk_trace_cpu_offset, cpu); + sibling_off = &per_cpu(blk_trace_cpu_offset, i); + *sibling_off = *cpu_off; + } + } + preempt_enable(); +#endif +} + +static __init int blk_trace_init(void) +{ + mutex_init(&blk_tree_mutex); + blk_trace_calibrate_offsets(); + blk_trace_set_ht_offsets(); + + return 0; +} + +module_init(blk_trace_init); + diff --git a/block/elevator.c b/block/elevator.c index db3d0d8296a..5e558c4689a 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -33,6 +33,7 @@ #include <linux/init.h> #include <linux/compiler.h> #include <linux/delay.h> +#include <linux/blktrace_api.h> #include <asm/uaccess.h> @@ -333,6 +334,8 @@ void elv_insert(request_queue_t *q, struct request *rq, int where) struct list_head *pos; unsigned ordseq; + blk_add_trace_rq(q, rq, BLK_TA_INSERT); + rq->q = q; switch (where) { @@ -499,6 +502,7 @@ struct request *elv_next_request(request_queue_t *q) * not be passed by new incoming requests */ rq->flags |= REQ_STARTED; + blk_add_trace_rq(q, rq, BLK_TA_ISSUE); } if (!q->boundary_rq || q->boundary_rq == rq) { diff --git a/block/ioctl.c b/block/ioctl.c index 35fdb7dc651..9cfa2e1ecb2 100644 --- a/block/ioctl.c +++ b/block/ioctl.c @@ -5,6 +5,7 @@ #include <linux/backing-dev.h> #include <linux/buffer_head.h> #include <linux/smp_lock.h> +#include <linux/blktrace_api.h> #include <asm/uaccess.h> static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user *arg) @@ -189,6 +190,11 @@ static int blkdev_locked_ioctl(struct file *file, struct block_device *bdev, return put_ulong(arg, bdev->bd_inode->i_size >> 9); case BLKGETSIZE64: return put_u64(arg, bdev->bd_inode->i_size); + case BLKTRACESTART: + case BLKTRACESTOP: + case BLKTRACESETUP: + case BLKTRACETEARDOWN: + return blk_trace_ioctl(bdev, cmd, (char __user *) arg); } return -ENOIOCTLCMD; } diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c index 6c793b196aa..062067fa7ea 100644 --- a/block/ll_rw_blk.c +++ b/block/ll_rw_blk.c @@ -28,6 +28,7 @@ #include <linux/writeback.h> #include <linux/interrupt.h> #include <linux/cpu.h> +#include <linux/blktrace_api.h> /* * for max sense size @@ -1556,8 +1557,10 @@ void blk_plug_device(request_queue_t *q) if (test_bit(QUEUE_FLAG_STOPPED, &q->queue_flags)) return; - if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) + if (!test_and_set_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags)) { mod_timer(&q->unplug_timer, jiffies + q->unplug_delay); + blk_add_trace_generic(q, NULL, 0, BLK_TA_PLUG); + } } EXPORT_SYMBOL(blk_plug_device); @@ -1621,14 +1624,21 @@ static void blk_backing_dev_unplug(struct backing_dev_info *bdi, /* * devices don't necessarily have an ->unplug_fn defined */ - if (q->unplug_fn) + if (q->unplug_fn) { + blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL, + q->rq.count[READ] + q->rq.count[WRITE]); + q->unplug_fn(q); + } } static void blk_unplug_work(void *data) { request_queue_t *q = data; + blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_IO, NULL, + q->rq.count[READ] + q->rq.count[WRITE]); + q->unplug_fn(q); } @@ -1636,6 +1646,9 @@ static void blk_unplug_timeout(unsigned long data) { request_queue_t *q = (request_queue_t *)data; + blk_add_trace_pdu_int(q, BLK_TA_UNPLUG_TIMER, NULL, + q->rq.count[READ] + q->rq.count[WRITE]); + kblockd_schedule_work(&q->unplug_work); } @@ -1753,6 +1766,9 @@ static void blk_release_queue(struct kobject *kobj) if (q->queue_tags) __blk_queue_free_tags(q); + if (q->blk_trace) + blk_trace_shutdown(q); + kmem_cache_free(requestq_cachep, q); } @@ -2129,6 +2145,8 @@ rq_starved: rq_init(q, rq); rq->rl = rl; + + blk_add_trace_generic(q, bio, rw, BLK_TA_GETRQ); out: return rq; } @@ -2157,6 +2175,8 @@ static struct request *get_request_wait(request_queue_t *q, int rw, if (!rq) { struct io_context *ioc; + blk_add_trace_generic(q, bio, rw, BLK_TA_SLEEPRQ); + __generic_unplug_device(q); spin_unlock_irq(q->queue_lock); io_schedule(); @@ -2210,6 +2230,8 @@ EXPORT_SYMBOL(blk_get_request); */ void blk_requeue_request(request_queue_t *q, struct request *rq) { + blk_add_trace_rq(q, rq, BLK_TA_REQUEUE); + if (blk_rq_tagged(rq)) blk_queue_end_tag(q, rq); @@ -2844,6 +2866,8 @@ static int __make_request(request_queue_t *q, struct bio *bio) if (!q->back_merge_fn(q, req, bio)) break; + blk_add_trace_bio(q, bio, BLK_TA_BACKMERGE); + req->biotail->bi_next = bio; req->biotail = bio; req->nr_sectors = req->hard_nr_sectors += nr_sectors; @@ -2859,6 +2883,8 @@ static int __make_request(request_queue_t *q, struct bio *bio) if (!q->front_merge_fn(q, req, bio)) break; + blk_add_trace_bio(q, bio, BLK_TA_FRONTMERGE); + bio->bi_next = req->bio; req->bio = bio; @@ -2976,6 +3002,7 @@ void generic_make_request(struct bio *bio) request_queue_t *q; sector_t maxsector; int ret, nr_sectors = bio_sectors(bio); + dev_t old_dev; might_sleep(); /* Test device or partition size, when known. */ @@ -3002,6 +3029,8 @@ void generic_make_request(struct bio *bio) * NOTE: we don't repeat the blk_size check for each new device. * Stacking drivers are expected to know what they are doing. */ + maxsector = -1; + old_dev = 0; do { char b[BDEVNAME_SIZE]; @@ -3034,6 +3063,15 @@ end_io: */ blk_partition_remap(bio); + if (maxsector != -1) + blk_add_trace_remap(q, bio, old_dev, bio->bi_sector, + maxsector); + + blk_add_trace_bio(q, bio, BLK_TA_QUEUE); + + maxsector = bio->bi_sector; + old_dev = bio->bi_bdev->bd_dev; + ret = q->make_request_fn(q, bio); } while (ret); } @@ -3153,6 +3191,8 @@ static int __end_that_request_first(struct request *req, int uptodate, int total_bytes, bio_nbytes, error, next_idx = 0; struct bio *bio; + blk_add_trace_rq(req->q, req, BLK_TA_COMPLETE); + /* * extend uptodate bool to allow < 0 value to be direct io error */ |