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Removed scsi host lock entirely from the command queueing path. Improves

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maximum IOPS by about 2.5%.


git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@2269 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Bart Van Assche
2010-09-25 15:58:44 +00:00
parent 99bfb0c117
commit fe82da8cb2
1 changed files with 107 additions and 7 deletions
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114
scripts/generate-kernel-with-srp-patches
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@@ -677,19 +677,74 @@ index 854ec81..f665cea 100644
enum dma_data_direction direction;
};
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 8a8f803..716f704 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -65,7 +65,7 @@ static struct class shost_class = {
**/
int scsi_host_set_state(struct Scsi_Host *shost, enum scsi_host_state state)
{
- enum scsi_host_state oldstate = shost->shost_state;
+ enum scsi_host_state oldstate = atomic_read(&shost->shost_state);
if (state == oldstate)
return 0;
@@ -136,7 +136,7 @@ int scsi_host_set_state(struct Scsi_Host *shost, enum scsi_host_state state)
}
break;
}
- shost->shost_state = state;
+ atomic_set(&shost->shost_state, state);
return 0;
illegal:
@@ -341,7 +341,7 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
shost->host_lock = &shost->default_lock;
spin_lock_init(shost->host_lock);
- shost->shost_state = SHOST_CREATED;
+ atomic_set(&shost->shost_state, SHOST_CREATED);
INIT_LIST_HEAD(&shost->__devices);
INIT_LIST_HEAD(&shost->__targets);
INIT_LIST_HEAD(&shost->eh_cmd_q);
@@ -503,7 +503,7 @@ EXPORT_SYMBOL(scsi_host_lookup);
**/
struct Scsi_Host *scsi_host_get(struct Scsi_Host *shost)
{
- if ((shost->shost_state == SHOST_DEL) ||
+ if (atomic_read(&shost->shost_state) == SHOST_DEL ||
!get_device(&shost->shost_gendev))
return NULL;
return shost;
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index ad0ed21..3819d66 100644
index ad0ed21..c150a3d 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -749,11 +749,16 @@ int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
if (unlikely(host->shost_state == SHOST_DEL)) {
@@ -737,23 +737,22 @@ int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
goto out;
}
- spin_lock_irqsave(host->host_lock, flags);
- /*
- * AK: unlikely race here: for some reason the timer could
- * expire before the serial number is set up below.
- *
- * TODO: kill serial or move to blk layer
- */
- scsi_cmd_get_serial(host, cmd);
+ cmd->serial_number = 1;
- if (unlikely(host->shost_state == SHOST_DEL)) {
+ if (unlikely(atomic_read(&host->shost_state) == SHOST_DEL)) {
cmd->result = (DID_NO_CONNECT << 16);
+ spin_lock_irqsave(host->host_lock, flags);
scsi_done(cmd);
+ spin_unlock_irqrestore(host->host_lock, flags);
} else {
trace_scsi_dispatch_cmd_start(cmd);
+ if (host->unlocked_qcmds)
+ spin_unlock_irqrestore(host->host_lock, flags);
+ if (!host->unlocked_qcmds)
+ spin_lock_irqsave(host->host_lock, flags);
rtn = host->hostt->queuecommand(cmd, scsi_done);
+ if (!host->unlocked_qcmds)
+ spin_unlock_irqrestore(host->host_lock, flags);
@@ -699,8 +754,21 @@ index ad0ed21..3819d66 100644
if (rtn) {
trace_scsi_dispatch_cmd_error(cmd, rtn);
if (rtn != SCSI_MLQUEUE_DEVICE_BUSY &&
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index c3f6737..cbcb096 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -188,7 +188,7 @@ static ssize_t
show_shost_state(struct device *dev, struct device_attribute *attr, char *buf)
{
struct Scsi_Host *shost = class_to_shost(dev);
- const char *name = scsi_host_state_name(shost->shost_state);
+ const char *name = scsi_host_state_name(atomic_read(&shost->shost_state));
if (!name)
return -EINVAL;
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index b7bdecb..1814c51 100644
index b7bdecb..d899f57 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -636,6 +636,9 @@ struct Scsi_Host {
@@ -713,7 +781,38 @@ index b7bdecb..1814c51 100644
/*
* Optional work queue to be utilized by the transport
*/
@@ -670,7 +673,7 @@ struct Scsi_Host {
unsigned int irq;
- enum scsi_host_state shost_state;
+ atomic_t shost_state; /* enum scsi_host_state */
/* ldm bits */
struct device shost_gendev, shost_dev;
@@ -730,9 +733,10 @@ static inline struct Scsi_Host *dev_to_shost(struct device *dev)
static inline int scsi_host_in_recovery(struct Scsi_Host *shost)
{
- return shost->shost_state == SHOST_RECOVERY ||
- shost->shost_state == SHOST_CANCEL_RECOVERY ||
- shost->shost_state == SHOST_DEL_RECOVERY ||
+ const int shost_state = atomic_read(&shost->shost_state);
+ return shost_state == SHOST_RECOVERY ||
+ shost_state == SHOST_CANCEL_RECOVERY ||
+ shost_state == SHOST_DEL_RECOVERY ||
shost->tmf_in_progress;
}
@@ -770,7 +774,7 @@ static inline struct device *scsi_get_device(struct Scsi_Host *shost)
**/
static inline int scsi_host_scan_allowed(struct Scsi_Host *shost)
{
- return shost->shost_state == SHOST_RUNNING;
+ return atomic_read(&shost->shost_state) == SHOST_RUNNING;
}
extern void scsi_unblock_requests(struct Scsi_Host *);
EOF
}
@@ -784,4 +883,5 @@ do
wget -O- -q "$url" | patch -p1 -s
done
echo "Applying locking-per-lun patch ..."
apply_locking_per_lun_patch