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Message-Id: <1161435477.3054.113.camel@dyn-9-152-230-71.boeblingen.de.ibm.com>
Date: Sat, 21 Oct 2006 14:57:57 +0200
From: Martin Peschke <mp3@...ibm.com>
To: Andrew Morton <akpm@...l.org>
Cc: linux-kernel@...r.kernel.org
Subject: [Patch 2/5] I/O statistics through request queues: queue
instrumentation
The most important part: the addition of statistics to struct
request_queue.
A few block layer API functions are required to make this work reliably:
blk_queue_stat_create() - setup (using a name from block device driver)
blk_queue_stat_issue() - "request issued to device" marker
blk_queue_stat_complete() - "got request completion interrupt" marker
Signed-off-by: Martin Peschke <mp3@...ibm.com>
---
block/ll_rw_blk.c | 157 +++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/blkdev.h | 46 ++++++++++++++
2 files changed, 203 insertions(+)
diff -urp a/include/linux/blkdev.h b/include/linux/blkdev.h
--- a/include/linux/blkdev.h 2006-10-21 14:20:09.000000000 +0200
+++ b/include/linux/blkdev.h 2006-10-21 01:37:26.000000000 +0200
@@ -14,6 +14,7 @@
#include <linux/bio.h>
#include <linux/module.h>
#include <linux/stringify.h>
+#include <linux/statistic.h>
#include <asm/scatterlist.h>
@@ -314,6 +315,12 @@ struct request {
*/
rq_end_io_fn *end_io;
void *end_io_data;
+
+#ifdef CONFIG_STATISTICS
+ struct timeval issued;
+ struct timeval completed;
+ int attempts;
+#endif
};
/*
@@ -362,6 +369,19 @@ struct blk_queue_tag {
atomic_t refcnt; /* map can be shared */
};
+enum blk_queue_stat {
+ BLK_STAT_SW, /* request size, write */
+ BLK_STAT_SR, /* request size, read */
+ BLK_STAT_RW, /* residual bytes, write */
+ BLK_STAT_RR, /* residual bytes, write */
+ BLK_STAT_LW, /* latency, write */
+ BLK_STAT_LR, /* latency, read */
+ BLK_STAT_AW, /* attempts, write */
+ BLK_STAT_AR, /* attempts, read */
+ BLK_STAT_QUD, /* queue used depth, issued to device */
+ _BLK_STAT_NUMBER
+};
+
struct request_queue
{
/*
@@ -479,6 +499,12 @@ struct request_queue
unsigned int bi_size;
struct mutex sysfs_lock;
+
+#ifdef CONFIG_STATISTICS
+ struct statistic_interface stat_if;
+ struct statistic stat[_BLK_STAT_NUMBER];
+ atomic_t issued;
+#endif
};
#define QUEUE_FLAG_CLUSTER 0 /* cluster several segments into 1 */
@@ -773,6 +799,26 @@ request_queue_t *blk_alloc_queue(gfp_t);
request_queue_t *blk_alloc_queue_node(gfp_t, int);
extern void blk_put_queue(request_queue_t *);
+#ifdef CONFIG_STATISTICS
+extern int blk_queue_stat_create(request_queue_t *q, const char *__name);
+extern void blk_queue_stat_issue(request_queue_t *q, struct request *rq);
+extern void blk_queue_stat_complete(request_queue_t *q, struct request *rq);
+#else
+static inline int blk_queue_stat_create(request_queue_t *q, const char *__name)
+{
+ return 0;
+}
+
+static inline void blk_queue_stat_issue(request_queue_t *q, struct request *rq)
+{
+}
+
+static inline void blk_queue_stat_complete(request_queue_t *q,
+ struct request *rq)
+{
+}
+#endif
+
/*
* tag stuff
*/
diff -urp a/block/ll_rw_blk.c b/block/ll_rw_blk.c
--- a/block/ll_rw_blk.c 2006-10-21 14:20:09.000000000 +0200
+++ b/block/ll_rw_blk.c 2006-10-21 13:27:10.000000000 +0200
@@ -28,6 +28,7 @@
#include <linux/interrupt.h>
#include <linux/cpu.h>
#include <linux/blktrace_api.h>
+#include <linux/statistic.h>
/*
* for max sense size
@@ -260,6 +261,9 @@ static void rq_init(request_queue_t *q,
rq->end_io = NULL;
rq->end_io_data = NULL;
rq->completion_data = NULL;
+#ifdef CONFIG_STATISTICS
+ rq->attempts = 0;
+#endif
}
/**
@@ -1780,6 +1784,10 @@ static void blk_release_queue(struct kob
blk_trace_shutdown(q);
+#ifdef CONFIG_STATISTICS
+ statistic_remove(&q->stat_if);
+#endif
+
kmem_cache_free(requestq_cachep, q);
}
@@ -1855,6 +1863,154 @@ request_queue_t *blk_alloc_queue_node(gf
}
EXPORT_SYMBOL(blk_alloc_queue_node);
+#ifdef CONFIG_STATISTICS
+static struct statistic_info blk_stat_info[] = {
+ [BLK_STAT_SW] = {
+ .name = "size_write",
+ .x_unit = "bytes",
+ .y_unit = "request",
+ .defaults = "type=sparse entries=256"
+ },
+ [BLK_STAT_SR] = {
+ .name = "size_read",
+ .x_unit = "bytes",
+ .y_unit = "request",
+ .defaults = "type=sparse entries=256"
+ },
+ [BLK_STAT_RW] = {
+ .name = "residual_write",
+ .x_unit = "bytes",
+ .y_unit = "request",
+ .defaults = "type=sparse entries=256"
+ },
+ [BLK_STAT_RR] = {
+ .name = "residual_read",
+ .x_unit = "bytes",
+ .y_unit = "request",
+ .defaults = "type=sparse entries=256"
+ },
+ [BLK_STAT_LW] = {
+ .name = "latency_write",
+ .x_unit = "microsec",
+ .y_unit = "request",
+ .defaults = "type=histogram_log2 entries=23 "
+ "base_interval=1 range_min=0"
+ },
+ [BLK_STAT_LR] = {
+ .name = "latency_read",
+ .x_unit = "microsec",
+ .y_unit = "request",
+ .defaults = "type=histogram_log2 entries=23 "
+ "base_interval=1 range_min=0"
+ },
+ [BLK_STAT_AW] = {
+ .name = "times_issued_write",
+ .x_unit = "attempts",
+ .y_unit = "request",
+ .defaults = "type=histogram_lin entries=8 "
+ "base_interval=1 range_min=0"
+ },
+ [BLK_STAT_AR] = {
+ .name = "times_issued_read",
+ .x_unit = "attempts",
+ .y_unit = "request",
+ .defaults = "type=histogram_lin entries=8 "
+ "base_interval=1 range_min=0"
+ },
+ [BLK_STAT_QUD] = {
+ .name = "queue_used_depth",
+ .x_unit = "requests",
+ .y_unit = "",
+ .defaults = "type=utilisation"
+ }
+};
+
+/**
+ * blk_queue_stat_create - setup request queue statistics
+ * @q: request queue
+ * @__name: users will see this as part of the statistics name
+ *
+ * Prepares a request queue for statistics data collection. This function
+ * might sleep. __name must be unique. For example, it could comprise a
+ * block device driver's name and the busid of the dev<driver name>-<busid>).
+ */
+int blk_queue_stat_create(request_queue_t *q, const char *__name)
+{
+ char name[64];
+
+ atomic_set(&q->issued, 0);
+ snprintf(name, 64, "blkq-%s", __name);
+ q->stat_if.stat = q->stat;
+ q->stat_if.info = blk_stat_info;
+ q->stat_if.number = _BLK_STAT_NUMBER;
+ return statistic_create(&q->stat_if, name);
+}
+EXPORT_SYMBOL_GPL(blk_queue_stat_create);
+
+/**
+ * blk_queue_stat_issue - notify statistics that this request is being issued
+ * @q: request queue
+ * @rq: request
+ *
+ * It's safe to call this function in any context.
+ * It is important to keep it as small as possible, as it would be called
+ * in a performance critical path of a device driver.
+ */
+void blk_queue_stat_issue(request_queue_t *q, struct request *rq)
+{
+ do_gettimeofday(&rq->issued);
+ statistic_inc(q->stat, BLK_STAT_QUD, atomic_inc_return(&q->issued));
+ rq->attempts++;
+}
+EXPORT_SYMBOL_GPL(blk_queue_stat_issue);
+
+/**
+ * blk_queue_stat_issue - notify statistics that this request is being issued
+ * @q: request queue
+ * @rq: request
+ *
+ * It's safe to call this function in any context.
+ * It is important to keep it as small as possible, as it would be called
+ * in a performance critical path of a device driver.
+ */
+void blk_queue_stat_complete(request_queue_t *q, struct request *rq)
+{
+ do_gettimeofday(&rq->completed);
+ atomic_dec(&q->issued);
+}
+EXPORT_SYMBOL_GPL(blk_queue_stat_complete);
+
+static void blk_queue_stat_end(request_queue_t *q, struct request *rq,
+ int bytes)
+{
+ s64 latency, size, residual;
+ unsigned long flags;
+
+ latency = timeval_to_us(&rq->completed) - timeval_to_us(&rq->issued);
+ size = blk_pc_request(rq) ? rq->data_len : rq->hard_nr_sectors << 9;
+ residual = size - bytes;
+
+ local_irq_save(flags);
+ if (rq_data_dir(rq) == WRITE) {
+ _statistic_inc(q->stat, BLK_STAT_SW, size);
+ _statistic_inc(q->stat, BLK_STAT_RW, residual);
+ _statistic_inc(q->stat, BLK_STAT_LW, latency);
+ _statistic_inc(q->stat, BLK_STAT_AW, rq->attempts);
+ } else if (rq_data_dir(rq) == READ) {
+ _statistic_inc(q->stat, BLK_STAT_SR, size);
+ _statistic_inc(q->stat, BLK_STAT_RR, residual);
+ _statistic_inc(q->stat, BLK_STAT_LR, latency);
+ _statistic_inc(q->stat, BLK_STAT_AR, rq->attempts);
+ }
+ local_irq_restore(flags);
+}
+#else
+static void blk_queue_stat_end(request_queue_t *q, struct request *rq,
+ int bytes)
+{
+}
+#endif /* CONFIG_STATISTICS */
+
/**
* blk_init_queue - prepare a request queue for use with a block device
* @rfn: The function to be called to process requests that have been
@@ -3249,6 +3405,7 @@ static int __end_that_request_first(stru
struct bio *bio;
blk_add_trace_rq(req->q, req, BLK_TA_COMPLETE);
+ blk_queue_stat_end(req->q, req, uptodate ? nr_bytes : 0);
/*
* extend uptodate bool to allow < 0 value to be direct io error
-
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