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[PATCH] blktrace: add timestamp message

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This adds a new timestamp message to blktrace, giving the timeofday when
we starting tracing. This helps user space correlate block trace events
with eg an application strace.

This requires a (compatible) update to blkparse. The changed blkparse
is still able to process traces generated by older kernels, and older
versions of blkparse should silently ignore the new records (because
they have a pid of 0).

Signed-off-by: Olaf Kirch <okir@suse.de>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Olaf Kirch 2006-12-01 10:39:12 +01:00 committed by Jens Axboe
parent 0215ffb08c
commit be1c63411a
2 changed files with 57 additions and 12 deletions
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57
block/blktrace.c
View file

@ -22,30 +22,61 @@
#include <linux/init.h>
#include <linux/mutex.h>
#include <linux/debugfs.h>
#include <linux/time.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 message.
*/
static inline unsigned int trace_note(struct blk_trace *bt,
pid_t pid, int action,
const void *data, size_t len)
{
struct blk_io_trace *t;
int cpu = smp_processor_id();
t = relay_reserve(bt->rchan, sizeof(*t) + len);
if (t == NULL)
return 0;
t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
t->time = sched_clock() - per_cpu(blk_trace_cpu_offset, cpu);
t->device = bt->dev;
t->action = action;
t->pid = pid;
t->cpu = cpu;
t->pdu_len = len;
memcpy((void *) t + sizeof(*t), data, len);
return blktrace_seq;
}
/*
* 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;
tsk->btrace_seq = trace_note(bt, tsk->pid,
BLK_TN_PROCESS,
tsk->comm, sizeof(tsk->comm));
}
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 void trace_note_time(struct blk_trace *bt)
{
struct timespec now;
unsigned long flags;
u32 words[2];
getnstimeofday(&now);
words[0] = now.tv_sec;
words[1] = now.tv_nsec;
local_irq_save(flags);
trace_note(bt, 0, BLK_TN_TIMESTAMP, words, sizeof(words));
local_irq_restore(flags);
}
static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
@ -394,6 +425,8 @@ static int blk_trace_startstop(request_queue_t *q, int start)
blktrace_seq++;
smp_mb();
bt->trace_state = Blktrace_running;
trace_note_time(bt);
ret = 0;
}
} else {

12
include/linux/blktrace_api.h
View file

@ -49,6 +49,15 @@ enum blktrace_act {
__BLK_TA_REMAP, /* bio was remapped */
};
/*
* Notify events.
*/
enum blktrace_notify {
__BLK_TN_PROCESS = 0, /* establish pid/name mapping */
__BLK_TN_TIMESTAMP, /* include system clock */
};
/*
* Trace actions in full. Additionally, read or write is masked
*/
@ -68,6 +77,9 @@ enum blktrace_act {
#define BLK_TA_BOUNCE (__BLK_TA_BOUNCE)
#define BLK_TA_REMAP (__BLK_TA_REMAP | BLK_TC_ACT(BLK_TC_QUEUE))
#define BLK_TN_PROCESS (__BLK_TN_PROCESS | BLK_TC_ACT(BLK_TC_NOTIFY))
#define BLK_TN_TIMESTAMP (__BLK_TN_TIMESTAMP | BLK_TC_ACT(BLK_TC_NOTIFY))
#define BLK_IO_TRACE_MAGIC 0x65617400
#define BLK_IO_TRACE_VERSION 0x07