On Feb 22 I asked for comments on this patch but have not received any. This
time I have a more specific question: does anyone have any objections to
adding statistics to st in this way? Any better suggestions? Adding the
statistics is a response to some user requests. They want some way to extract
data from st for performance monitoring.
This message contains a slightly refined version of the patch against
2.6.11-bk7 +
st patches in scsi-misc-2.6 + the three st patches I have sent yesterday and
today.
This patch adds a stat file to the primary st directory in /sys of each tape
(e.g., /sys/class/scsi_tape/st0/stat). The contents of the file match the
contents of the stat files in the subdirectories of /sys/block so that the
same tools could be used to analyze all stat files (provided they find the
stat files).
Some Unices implement statistics for each tape partition but this patch
does not count the partitions separately.
Sebastien Godard, the systat maintainer, has expressed his interest into
adding support for the tape statistics to systat.
Signed-off-by: Kai Makisara <[EMAIL PROTECTED]>
--- linux-2.6.11-bk7-k4/drivers/scsi/st.c 2005-03-13 19:24:29.000000000
+0200
+++ linux-2.6.11-bk7-k5/drivers/scsi/st.c 2005-03-13 21:21:35.000000000
+0200
@@ -392,6 +392,14 @@ static void st_sleep_done(struct scsi_cm
{
struct scsi_tape *STp =
container_of(SCpnt->request->rq_disk->private_data,
struct scsi_tape, driver);
+ unsigned long ticks = jiffies - STp->tapestats.stamp;
+
+ STp->tapestats.io_ticks += ticks;
+ STp->tapestats.in_flight--;
+ if (SCpnt->cmnd[0] == WRITE_6)
+ STp->tapestats.write_ticks += ticks;
+ else if (SCpnt->cmnd[0] == READ_6)
+ STp->tapestats.read_ticks += ticks;
(STp->buffer)->cmdstat.midlevel_result = SCpnt->result;
SCpnt->request->rq_status = RQ_SCSI_DONE;
@@ -423,6 +431,16 @@ st_do_scsi(struct scsi_request * SRpnt,
}
}
+ if (cmd[0] == WRITE_6) {
+ STp->tapestats.write_bytes += bytes;
+ STp->tapestats.writes++;
+ }
+ else if (cmd[0] == READ_6) {
+ STp->tapestats.read_bytes += bytes;
+ STp->tapestats.reads++;
+ }
+ STp->tapestats.in_flight++;
+
init_completion(&STp->wait);
SRpnt->sr_use_sg = STp->buffer->do_dio || (bytes >
(STp->buffer)->frp[0].length);
if (SRpnt->sr_use_sg) {
@@ -439,6 +457,8 @@ st_do_scsi(struct scsi_request * SRpnt,
SRpnt->sr_request->rq_disk = STp->disk;
STp->buffer->cmdstat.have_sense = 0;
+ STp->tapestats.stamp = jiffies;
+
scsi_do_req(SRpnt, (void *) cmd, bp, bytes,
st_sleep_done, timeout, retries);
@@ -3960,6 +3980,7 @@ static int st_probe(struct device *dev)
STm->cdevs[j] = cdev;
}
+ STm->tapestats = &tpnt->tapestats;
do_create_class_files(tpnt, dev_num, mode);
}
@@ -4240,6 +4261,28 @@ static ssize_t st_defcompression_show(st
CLASS_DEVICE_ATTR(default_compression, S_IRUGO, st_defcompression_show, NULL);
+static ssize_t st_stat_show(struct class_device *class_dev, char *buf)
+{
+ struct st_modedef *STm = (struct st_modedef
*)class_get_devdata(class_dev);
+ ssize_t l = 0;
+
+ l = snprintf(buf, PAGE_SIZE,
+ "%8u %8u %8llu %8u "
+ "%8u %8u %8llu %8u "
+ "%8u %8u %8u"
+ "\n",
+ STm->tapestats->reads, 0, STm->tapestats->read_bytes >> 9,
+ jiffies_to_msecs(STm->tapestats->read_ticks),
+ STm->tapestats->writes, 0, STm->tapestats->write_bytes >>
9,
+ jiffies_to_msecs(STm->tapestats->write_ticks),
+ STm->tapestats->in_flight,
+ jiffies_to_msecs(STm->tapestats->io_ticks),
+ jiffies_to_msecs(STm->tapestats->io_ticks));
+ return l;
+}
+
+CLASS_DEVICE_ATTR(stat, S_IRUGO, st_stat_show, NULL);
+
static void do_create_class_files(struct scsi_tape *STp, int dev_num, int mode)
{
int i, rew, error;
@@ -4276,6 +4319,8 @@ static void do_create_class_files(struct
class_device_create_file(st_class_member,
&class_device_attr_default_compression);
if (mode == 0 && rew == 0) {
+ class_device_create_file(st_class_member,
+ &class_device_attr_stat);
error =
sysfs_create_link(&STp->device->sdev_gendev.kobj,
&st_class_member->kobj,
"tape");
--- linux-2.6.11-bk7-k4/drivers/scsi/st.h 2005-03-03 21:26:29.000000000
+0200
+++ linux-2.6.11-bk7-k5/drivers/scsi/st.h 2005-03-13 22:09:58.000000000
+0200
@@ -57,6 +57,7 @@ struct st_modedef {
unsigned char default_compression; /* 0 = don't touch, etc */
short default_density; /* Forced density, -1 = no value */
int default_blksize; /* Forced blocksize, -1 = no value */
+ struct tape_stats *tapestats;
struct cdev *cdevs[2]; /* Auto-rewind and non-rewind devices */
};
@@ -83,6 +84,16 @@ struct st_partstat {
#define ST_NBR_PARTITIONS 4
+/* The performance counters */
+struct tape_stats {
+ u64 read_bytes, write_bytes;
+ unsigned int reads, writes;
+ unsigned int in_flight;
+ unsigned long read_ticks, write_ticks;
+ unsigned long io_ticks;
+ unsigned long stamp;
+};
+
/* The tape drive descriptor */
struct scsi_tape {
struct scsi_driver *driver;
@@ -144,6 +155,8 @@ struct scsi_tape {
int recover_count; /* From tape opening */
int recover_reg; /* From last status call */
+ struct tape_stats tapestats; /* the performance counters */
+
#if DEBUG
unsigned char write_pending;
int nbr_finished;
--- linux-2.6.11-bk7-k4/Documentation/scsi/st.txt 2005-03-07
21:14:44.000000000 +0200
+++ linux-2.6.11-bk7-k5/Documentation/scsi/st.txt 2005-03-13
22:23:11.000000000 +0200
@@ -2,7 +2,7 @@ This file contains brief information abo
The driver is currently maintained by Kai Mäkisara (email
[EMAIL PROTECTED])
-Last modified: Mon Mar 7 21:14:44 2005 by kai.makisara
+Last modified: Sun Mar 13 22:23:11 2005 by kai.makisara
BASICS
@@ -136,6 +136,11 @@ file 'dev' contains the device numbers c
A link named 'tape' is made from the SCSI device directory to the class
directory corresponding to the mode 0 auto-rewind device (e.g., st0).
+The same directory also includes the file stat that contains statistics for
+the device use. The format of the file is the same as the stat file for the
+block devices (see linux/Documentation/iostats.txt). Some of the fields are
+zero because they are not applicable to this driver.
+
BSD AND SYS V SEMANTICS
