[PATCH] scsi: megaraid_sas - throttle io if cmds are in risk ofbeing timed-out
From: Sumant Patro
Date: Thu Mar 01 2007 - 21:43:54 EST
Driver to throttle IO to reduce risk of OS timing out cmds.
Implemented a circular queue to keep track of pending OS cmds in FW.
This queue is periodically (every 10 sec) checked by a timer routine.
If there is any cmd that is in risk of getting timed-out by the OS,
the host->can_queue is reduced to 16 and MEGASAS_FW_BUSY flag is set.
The host->can_queue will be restored to default value when the following
two conditions are met : 5 secs has elapsed and the # of outstanding cmds
in FW is less than 17.
Also increased the per cmd timeout to 120*HZ from 90*HZ.
Signed-off-by: Sumant Patro <sumant.patro@xxxxxxx>
---
drivers/scsi/megaraid/megaraid_sas.c | 118 ++++++++++++++++++++++++-
drivers/scsi/megaraid/megaraid_sas.h | 25 ++++-
2 files changed, 136 insertions(+), 7 deletions(-)
diff -uprN linux-orig/drivers/scsi/megaraid/megaraid_sas.c linux-new/drivers/scsi/megaraid/megaraid_sas.c
--- linux-orig/drivers/scsi/megaraid/megaraid_sas.c 2007-03-01 06:04:40.000000000 -0800
+++ linux-new/drivers/scsi/megaraid/megaraid_sas.c 2007-03-01 10:26:35.000000000 -0800
@@ -10,7 +10,7 @@
* 2 of the License, or (at your option) any later version.
*
* FILE : megaraid_sas.c
- * Version : v00.00.03.10-rc1
+ * Version : v00.00.03.10-rc2
*
* Authors:
* (email-id : megaraidlinux@xxxxxxx)
@@ -112,6 +112,15 @@ megasas_return_cmd(struct megasas_instan
{
unsigned long flags;
+ if (cmd->watchdog_slot != 0xff) {
+ spin_lock_irqsave(&instance->watchdog_lock, flags);
+
+ instance->watchdog_arr[cmd->watchdog_slot]--;
+ cmd->watchdog_slot = 0xff;
+
+ spin_unlock_irqrestore(&instance->watchdog_lock, flags);
+ }
+
spin_lock_irqsave(&instance->cmd_pool_lock, flags);
cmd->scmd = NULL;
@@ -841,6 +850,7 @@ megasas_queue_command(struct scsi_cmnd *
u32 frame_count;
struct megasas_cmd *cmd;
struct megasas_instance *instance;
+ unsigned long flags;
instance = (struct megasas_instance *)
scmd->device->host->hostdata;
@@ -888,6 +898,16 @@ megasas_queue_command(struct scsi_cmnd *
cmd->scmd = scmd;
/*
+ * Update watchdog array before sending cmd to FW
+ */
+ spin_lock_irqsave(&instance->watchdog_lock, flags);
+
+ cmd->watchdog_slot = instance->watchdog_head;
+ instance->watchdog_arr[cmd->watchdog_slot]++;
+
+ spin_unlock_irqrestore(&instance->watchdog_lock, flags);
+
+ /*
* Issue the command to the FW
*/
atomic_inc(&instance->fw_outstanding);
@@ -919,7 +939,7 @@ static int megasas_slave_configure(struc
* The RAID firmware may require extended timeouts.
*/
if (sdev->channel >= MEGASAS_MAX_PD_CHANNELS)
- sdev->timeout = 90 * HZ;
+ sdev->timeout = 120 * HZ;
return 0;
}
@@ -981,8 +1001,8 @@ static int megasas_generic_reset(struct
instance = (struct megasas_instance *)scmd->device->host->hostdata;
- scmd_printk(KERN_NOTICE, scmd, "megasas: RESET -%ld cmd=%x\n",
- scmd->serial_number, scmd->cmnd[0]);
+ scmd_printk(KERN_NOTICE, scmd, "megasas: RESET -%ld cmd=%x, retries=%x\n",
+ scmd->serial_number, scmd->cmnd[0], scmd->retries);
if (instance->hw_crit_error) {
printk(KERN_ERR "megasas: cannot recover from previous reset "
@@ -1714,6 +1734,7 @@ static int megasas_alloc_cmds(struct meg
memset(cmd, 0, sizeof(struct megasas_cmd));
cmd->index = i;
cmd->instance = instance;
+ cmd->watchdog_slot = 0xff;
list_add_tail(&cmd->list, &instance->cmd_pool);
}
@@ -1828,9 +1849,80 @@ static void megasas_complete_cmd_dpc(uns
}
*instance->consumer = producer;
+
+ /*
+ * Check if we can restore can_queue
+ */
+ if (instance->flag & MEGASAS_FW_BUSY
+ && time_after(jiffies, instance->last_time + 5 * HZ)
+ && atomic_read(&instance->fw_outstanding) < 17) {
+
+ instance->flag &= ~MEGASAS_FW_BUSY;
+ instance->host->can_queue =
+ instance->max_fw_cmds - MEGASAS_INT_CMDS;
+ }
+}
+
+/**
+ * megasas_start_timer - Initializes a timer object
+ * @instance: Adapter soft state
+ * @timer: timer object to be initialized
+ * @fn: timer function
+ * @interval: time interval between timer function call
+ *
+ */
+static inline void
+megasas_start_timer(struct megasas_instance *instance,
+ struct timer_list *timer,
+ void *fn, unsigned long interval)
+{
+ init_timer(timer);
+ timer->expires = jiffies + interval;
+ timer->data = (unsigned long)instance;
+ timer->function = fn;
+ add_timer(timer);
}
/**
+ * megasas_throttle_timer - Timer fn
+ * @instance_addr: Address of adapter soft state
+ *
+ * Verifies and sets the FW busy flag if there is any pending cmd
+ * with the FW that is in risk of being timed-out by the OS
+ */
+static void
+megasas_throttle_timer(unsigned long instance_addr)
+{
+ unsigned long flags;
+ u32 pending;
+ struct megasas_instance *instance = (struct megasas_instance *)instance_addr;
+
+ spin_lock_irqsave(&instance->watchdog_lock, flags);
+
+ instance->watchdog_head++;
+ if (instance->watchdog_head == MEGASAS_MAX_WATCHDOG_SLOTS)
+ instance->watchdog_head = 0;
+
+ if (instance->watchdog_head == instance->watchdog_tail) {
+ pending = instance->watchdog_arr[instance->watchdog_tail];
+ if (pending) {
+ /* FW is busy, throttle IO */
+ instance->host->can_queue = 16;
+ instance->last_time = jiffies;
+ instance->flag |= MEGASAS_FW_BUSY;
+ }
+ instance->watchdog_tail++;
+ if (instance->watchdog_tail == MEGASAS_MAX_WATCHDOG_SLOTS)
+ instance->watchdog_tail = 0;
+ }
+ spin_unlock_irqrestore(&instance->watchdog_lock, flags);
+
+ /* Restart timer */
+ mod_timer(&instance->throttle_timer,
+ jiffies + MEGASAS_WATCHDOG_TIMER_INTERVAL);
+}
+
+/**
* megasas_init_mfi - Initializes the FW
* @instance: Adapter soft state
*
@@ -1851,6 +1943,7 @@ static int megasas_init_mfi(struct megas
struct megasas_init_queue_info *initq_info;
dma_addr_t init_frame_h;
dma_addr_t initq_info_h;
+ int i;
/*
* Map the message registers
@@ -2006,6 +2099,19 @@ static int megasas_init_mfi(struct megas
tasklet_init(&instance->isr_tasklet, megasas_complete_cmd_dpc,
(unsigned long)instance);
+
+ /* Initialize watchdog data structs */
+ for (i = 0; i < MEGASAS_MAX_WATCHDOG_SLOTS; i++)
+ instance->watchdog_arr[i] = 0;
+
+ instance->watchdog_head = 0;
+ instance->watchdog_tail = MEGASAS_MAX_WATCHDOG_SLOTS - 1;
+
+ /* Initialize the throttle IO timer */
+ megasas_start_timer(instance, &instance->throttle_timer,
+ megasas_throttle_timer,
+ MEGASAS_WATCHDOG_TIMER_INTERVAL);
+
return 0;
fail_fw_init:
@@ -2385,6 +2491,7 @@ megasas_probe_one(struct pci_dev *pdev,
init_waitqueue_head(&instance->abort_cmd_wait_q);
spin_lock_init(&instance->cmd_pool_lock);
+ spin_lock_init(&instance->watchdog_lock);
sema_init(&instance->aen_mutex, 1);
sema_init(&instance->ioctl_sem, MEGASAS_INT_CMDS);
@@ -2398,6 +2505,8 @@ megasas_probe_one(struct pci_dev *pdev,
instance->init_id = MEGASAS_DEFAULT_INIT_ID;
megasas_dbg_lvl = 0;
+ instance->flag = 0;
+ instance->last_time = 0;
/*
* Initialize MFI Firmware
@@ -2566,6 +2675,7 @@ static void megasas_detach_one(struct pc
megasas_flush_cache(instance);
megasas_shutdown_controller(instance);
tasklet_kill(&instance->isr_tasklet);
+ del_timer_sync(&instance->throttle_timer);
/*
* Take the instance off the instance array. Note that we will not
diff -uprN linux-orig/drivers/scsi/megaraid/megaraid_sas.h linux-new/drivers/scsi/megaraid/megaraid_sas.h
--- linux-orig/drivers/scsi/megaraid/megaraid_sas.h 2007-03-01 06:04:40.000000000 -0800
+++ linux-new/drivers/scsi/megaraid/megaraid_sas.h 2007-03-01 10:40:16.000000000 -0800
@@ -18,9 +18,9 @@
/*
* MegaRAID SAS Driver meta data
*/
-#define MEGASAS_VERSION "00.00.03.10-rc1"
-#define MEGASAS_RELDATE "Feb 14, 2007"
-#define MEGASAS_EXT_VERSION "Wed Feb 14 10:14:25 PST 2007"
+#define MEGASAS_VERSION "00.00.03.10-rc2"
+#define MEGASAS_RELDATE "Mar 01, 2007"
+#define MEGASAS_EXT_VERSION "Thu Mar 01 10:07:34 PST 2007"
/*
* Device IDs
@@ -539,6 +539,10 @@ struct megasas_ctrl_info {
#define MEGASAS_DBG_LVL 1
+#define MEGASAS_WATCHDOG_TIMER_INTERVAL 10*HZ
+#define MEGASAS_MAX_WATCHDOG_SLOTS 8
+#define MEGASAS_FW_BUSY 1
+
/*
* When SCSI mid-layer calls driver's reset routine, driver waits for
* MEGASAS_RESET_WAIT_TIME seconds for all outstanding IO to complete. Note
@@ -1104,6 +1108,18 @@ struct megasas_instance {
struct megasas_instance_template *instancet;
struct tasklet_struct isr_tasklet;
+
+ /*
+ * watchdog data structs used to throttle IO if required
+ */
+ u8 flag;
+ u8 watchdog_head;
+ u8 watchdog_tail;
+ u8 resvd;
+ unsigned long last_time;
+ u32 watchdog_arr[MEGASAS_MAX_WATCHDOG_SLOTS];
+ spinlock_t watchdog_lock;
+ struct timer_list throttle_timer;
};
#define MEGASAS_IS_LOGICAL(scp) \
@@ -1129,6 +1145,9 @@ struct megasas_cmd {
struct scsi_cmnd *scmd;
struct megasas_instance *instance;
u32 frame_count;
+
+ u8 watchdog_slot;
+ u8 resvd[3];
};
#define MAX_MGMT_ADAPTERS 1024
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/