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linux/include/scsi/scsi_device.h
Jens Axboe 9937a5e2f3 scsi: remove performance regression due to async queue run 
Commit c21e6beb removed our queue request_fn re-enter
protection, and defaulted to always running the queues from
kblockd to be safe. This was a known potential slow down,
but should be safe.

Unfortunately this is causing big performance regressions for
some, so we need to improve this logic. Looking into the details
of the re-enter, the real issue is on requeue of requests.

Requeue of requests upon seeing a BUSY condition from the device
ends up re-running the queue, causing traces like this:

scsi_request_fn()
        scsi_dispatch_cmd()
                scsi_queue_insert()
                        __scsi_queue_insert()
                                scsi_run_queue()
					scsi_request_fn()
						...

potentially causing the issue we want to avoid. So special
case the requeue re-run of the queue, but improve it to offload
the entire run of local queue and starved queue from a single
workqueue callback. This is a lot better than potentially
kicking off a workqueue run for each device seen.

This also fixes the issue of the local device going into recursion,
since the above mentioned commit never moved that queue run out
of line.

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-05-17 11:04:44 +02:00

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#ifndef _SCSI_SCSI_DEVICE_H
#define _SCSI_SCSI_DEVICE_H
#include <linux/device.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
#include <linux/blkdev.h>
#include <scsi/scsi.h>
#include <asm/atomic.h>
struct request_queue;
struct scsi_cmnd;
struct scsi_lun;
struct scsi_sense_hdr;
struct scsi_mode_data {
__u32 length;
__u16 block_descriptor_length;
__u8 medium_type;
__u8 device_specific;
__u8 header_length;
__u8 longlba:1;
};
/*
* sdev state: If you alter this, you also need to alter scsi_sysfs.c
* (for the ascii descriptions) and the state model enforcer:
* scsi_lib:scsi_device_set_state().
*/
enum scsi_device_state {
SDEV_CREATED = 1, /* device created but not added to sysfs
* Only internal commands allowed (for inq) */
SDEV_RUNNING, /* device properly configured
* All commands allowed */
SDEV_CANCEL, /* beginning to delete device
* Only error handler commands allowed */
SDEV_DEL, /* device deleted
* no commands allowed */
SDEV_QUIESCE, /* Device quiescent. No block commands
* will be accepted, only specials (which
* originate in the mid-layer) */
SDEV_OFFLINE, /* Device offlined (by error handling or
* user request */
SDEV_BLOCK, /* Device blocked by scsi lld. No
* scsi commands from user or midlayer
* should be issued to the scsi
* lld. */
SDEV_CREATED_BLOCK, /* same as above but for created devices */
};
enum scsi_device_event {
SDEV_EVT_MEDIA_CHANGE = 1, /* media has changed */
SDEV_EVT_LAST = SDEV_EVT_MEDIA_CHANGE,
SDEV_EVT_MAXBITS = SDEV_EVT_LAST + 1
};
struct scsi_event {
enum scsi_device_event evt_type;
struct list_head node;
/* put union of data structures, for non-simple event types,
* here
*/
};
struct scsi_device {
struct Scsi_Host *host;
struct request_queue *request_queue;
/* the next two are protected by the host->host_lock */
struct list_head siblings; /* list of all devices on this host */
struct list_head same_target_siblings; /* just the devices sharing same target id */
/* this is now protected by the request_queue->queue_lock */
unsigned int device_busy; /* commands actually active on
* low-level. protected by queue_lock. */
spinlock_t list_lock;
struct list_head cmd_list; /* queue of in use SCSI Command structures */
struct list_head starved_entry;
struct scsi_cmnd *current_cmnd; /* currently active command */
unsigned short queue_depth; /* How deep of a queue we want */
unsigned short max_queue_depth; /* max queue depth */
unsigned short last_queue_full_depth; /* These two are used by */
unsigned short last_queue_full_count; /* scsi_track_queue_full() */
unsigned long last_queue_full_time; /* last queue full time */
unsigned long queue_ramp_up_period; /* ramp up period in jiffies */
#define SCSI_DEFAULT_RAMP_UP_PERIOD (120 * HZ)
unsigned long last_queue_ramp_up; /* last queue ramp up time */
unsigned int id, lun, channel;
unsigned int manufacturer; /* Manufacturer of device, for using
* vendor-specific cmd's */
unsigned sector_size; /* size in bytes */
void *hostdata; /* available to low-level driver */
char type;
char scsi_level;
char inq_periph_qual; /* PQ from INQUIRY data */
unsigned char inquiry_len; /* valid bytes in 'inquiry' */
unsigned char * inquiry; /* INQUIRY response data */
const char * vendor; /* [back_compat] point into 'inquiry' ... */
const char * model; /* ... after scan; point to static string */
const char * rev; /* ... "nullnullnullnull" before scan */
unsigned char current_tag; /* current tag */
struct scsi_target *sdev_target; /* used only for single_lun */
unsigned int sdev_bflags; /* black/white flags as also found in
* scsi_devinfo.[hc]. For now used only to
* pass settings from slave_alloc to scsi
* core. */
unsigned writeable:1;
unsigned removable:1;
unsigned changed:1; /* Data invalid due to media change */
unsigned busy:1; /* Used to prevent races */
unsigned lockable:1; /* Able to prevent media removal */
unsigned locked:1; /* Media removal disabled */
unsigned borken:1; /* Tell the Seagate driver to be
* painfully slow on this device */
unsigned disconnect:1; /* can disconnect */
unsigned soft_reset:1; /* Uses soft reset option */
unsigned sdtr:1; /* Device supports SDTR messages */
unsigned wdtr:1; /* Device supports WDTR messages */
unsigned ppr:1; /* Device supports PPR messages */
unsigned tagged_supported:1; /* Supports SCSI-II tagged queuing */
unsigned simple_tags:1; /* simple queue tag messages are enabled */
unsigned ordered_tags:1;/* ordered queue tag messages are enabled */
unsigned was_reset:1; /* There was a bus reset on the bus for
* this device */
unsigned expecting_cc_ua:1; /* Expecting a CHECK_CONDITION/UNIT_ATTN
* because we did a bus reset. */
unsigned use_10_for_rw:1; /* first try 10-byte read / write */
unsigned use_10_for_ms:1; /* first try 10-byte mode sense/select */
unsigned skip_ms_page_8:1; /* do not use MODE SENSE page 0x08 */
unsigned skip_ms_page_3f:1; /* do not use MODE SENSE page 0x3f */
unsigned use_192_bytes_for_3f:1; /* ask for 192 bytes from page 0x3f */
unsigned no_start_on_add:1; /* do not issue start on add */
unsigned allow_restart:1; /* issue START_UNIT in error handler */
unsigned manage_start_stop:1; /* Let HLD (sd) manage start/stop */
unsigned start_stop_pwr_cond:1; /* Set power cond. in START_STOP_UNIT */
unsigned no_uld_attach:1; /* disable connecting to upper level drivers */
unsigned select_no_atn:1;
unsigned fix_capacity:1; /* READ_CAPACITY is too high by 1 */
unsigned guess_capacity:1; /* READ_CAPACITY might be too high by 1 */
unsigned retry_hwerror:1; /* Retry HARDWARE_ERROR */
unsigned last_sector_bug:1; /* do not use multisector accesses on
SD_LAST_BUGGY_SECTORS */
unsigned no_read_disc_info:1; /* Avoid READ_DISC_INFO cmds */
unsigned no_read_capacity_16:1; /* Avoid READ_CAPACITY_16 cmds */
unsigned is_visible:1; /* is the device visible in sysfs */
DECLARE_BITMAP(supported_events, SDEV_EVT_MAXBITS); /* supported events */
struct list_head event_list; /* asserted events */
struct work_struct event_work;
unsigned int device_blocked; /* Device returned QUEUE_FULL. */
unsigned int max_device_blocked; /* what device_blocked counts down from */
#define SCSI_DEFAULT_DEVICE_BLOCKED 3
atomic_t iorequest_cnt;
atomic_t iodone_cnt;
atomic_t ioerr_cnt;
struct device sdev_gendev,
sdev_dev;
struct execute_work ew; /* used to get process context on put */
struct work_struct requeue_work;
struct scsi_dh_data *scsi_dh_data;
enum scsi_device_state sdev_state;
unsigned long sdev_data[0];
} __attribute__((aligned(sizeof(unsigned long))));
struct scsi_dh_devlist {
char *vendor;
char *model;
};
typedef void (*activate_complete)(void *, int);
struct scsi_device_handler {
/* Used by the infrastructure */
struct list_head list; /* list of scsi_device_handlers */
int idx;
/* Filled by the hardware handler */
struct module *module;
const char *name;
const struct scsi_dh_devlist *devlist;
int (*check_sense)(struct scsi_device *, struct scsi_sense_hdr *);
int (*attach)(struct scsi_device *);
void (*detach)(struct scsi_device *);
int (*activate)(struct scsi_device *, activate_complete, void *);
int (*prep_fn)(struct scsi_device *, struct request *);
int (*set_params)(struct scsi_device *, const char *);
};
struct scsi_dh_data {
struct scsi_device_handler *scsi_dh;
struct scsi_device *sdev;
struct kref kref;
char buf[0];
};
#define to_scsi_device(d) \
container_of(d, struct scsi_device, sdev_gendev)
#define class_to_sdev(d) \
container_of(d, struct scsi_device, sdev_dev)
#define transport_class_to_sdev(class_dev) \
to_scsi_device(class_dev->parent)
#define sdev_printk(prefix, sdev, fmt, a...) \
dev_printk(prefix, &(sdev)->sdev_gendev, fmt, ##a)
#define scmd_printk(prefix, scmd, fmt, a...) \
(scmd)->request->rq_disk ? \
sdev_printk(prefix, (scmd)->device, "[%s] " fmt, \
(scmd)->request->rq_disk->disk_name, ##a) : \
sdev_printk(prefix, (scmd)->device, fmt, ##a)
enum scsi_target_state {
STARGET_CREATED = 1,
STARGET_RUNNING,
STARGET_DEL,
};
/*
* scsi_target: representation of a scsi target, for now, this is only
* used for single_lun devices. If no one has active IO to the target,
* starget_sdev_user is NULL, else it points to the active sdev.
*/
struct scsi_target {
struct scsi_device *starget_sdev_user;
struct list_head siblings;
struct list_head devices;
struct device dev;
unsigned int reap_ref; /* protected by the host lock */
unsigned int channel;
unsigned int id; /* target id ... replace
* scsi_device.id eventually */
unsigned int create:1; /* signal that it needs to be added */
unsigned int single_lun:1; /* Indicates we should only
* allow I/O to one of the luns
* for the device at a time. */
unsigned int pdt_1f_for_no_lun; /* PDT = 0x1f */
/* means no lun present */
/* commands actually active on LLD. protected by host lock. */
unsigned int target_busy;
/*
* LLDs should set this in the slave_alloc host template callout.
* If set to zero then there is not limit.
*/
unsigned int can_queue;
unsigned int target_blocked;
unsigned int max_target_blocked;
#define SCSI_DEFAULT_TARGET_BLOCKED 3
char scsi_level;
struct execute_work ew;
enum scsi_target_state state;
void *hostdata; /* available to low-level driver */
unsigned long starget_data[0]; /* for the transport */
/* starget_data must be the last element!!!! */
} __attribute__((aligned(sizeof(unsigned long))));
#define to_scsi_target(d) container_of(d, struct scsi_target, dev)
static inline struct scsi_target *scsi_target(struct scsi_device *sdev)
{
return to_scsi_target(sdev->sdev_gendev.parent);
}
#define transport_class_to_starget(class_dev) \
to_scsi_target(class_dev->parent)
#define starget_printk(prefix, starget, fmt, a...) \
dev_printk(prefix, &(starget)->dev, fmt, ##a)
extern struct scsi_device *__scsi_add_device(struct Scsi_Host *,
uint, uint, uint, void *hostdata);
extern int scsi_add_device(struct Scsi_Host *host, uint channel,
uint target, uint lun);
extern int scsi_register_device_handler(struct scsi_device_handler *scsi_dh);
extern void scsi_remove_device(struct scsi_device *);
extern int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh);
extern int scsi_device_get(struct scsi_device *);
extern void scsi_device_put(struct scsi_device *);
extern struct scsi_device *scsi_device_lookup(struct Scsi_Host *,
uint, uint, uint);
extern struct scsi_device *__scsi_device_lookup(struct Scsi_Host *,
uint, uint, uint);
extern struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *,
uint);
extern struct scsi_device *__scsi_device_lookup_by_target(struct scsi_target *,
uint);
extern void starget_for_each_device(struct scsi_target *, void *,
void (*fn)(struct scsi_device *, void *));
extern void __starget_for_each_device(struct scsi_target *, void *,
void (*fn)(struct scsi_device *,
void *));
/* only exposed to implement shost_for_each_device */
extern struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *,
struct scsi_device *);
/**
* shost_for_each_device - iterate over all devices of a host
* @sdev: the &struct scsi_device to use as a cursor
* @shost: the &struct scsi_host to iterate over
*
* Iterator that returns each device attached to @shost. This loop
* takes a reference on each device and releases it at the end. If
* you break out of the loop, you must call scsi_device_put(sdev).
*/
#define shost_for_each_device(sdev, shost) \
for ((sdev) = __scsi_iterate_devices((shost), NULL); \
(sdev); \
(sdev) = __scsi_iterate_devices((shost), (sdev)))
/**
* __shost_for_each_device - iterate over all devices of a host (UNLOCKED)
* @sdev: the &struct scsi_device to use as a cursor
* @shost: the &struct scsi_host to iterate over
*
* Iterator that returns each device attached to @shost. It does _not_
* take a reference on the scsi_device, so the whole loop must be
* protected by shost->host_lock.
*
* Note: The only reason to use this is because you need to access the
* device list in interrupt context. Otherwise you really want to use
* shost_for_each_device instead.
*/
#define __shost_for_each_device(sdev, shost) \
list_for_each_entry((sdev), &((shost)->__devices), siblings)
extern void scsi_adjust_queue_depth(struct scsi_device *, int, int);
extern int scsi_track_queue_full(struct scsi_device *, int);
extern int scsi_set_medium_removal(struct scsi_device *, char);
extern int scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
unsigned char *buffer, int len, int timeout,
int retries, struct scsi_mode_data *data,
struct scsi_sense_hdr *);
extern int scsi_mode_select(struct scsi_device *sdev, int pf, int sp,
int modepage, unsigned char *buffer, int len,
int timeout, int retries,
struct scsi_mode_data *data,
struct scsi_sense_hdr *);
extern int scsi_test_unit_ready(struct scsi_device *sdev, int timeout,
int retries, struct scsi_sense_hdr *sshdr);
extern int scsi_get_vpd_page(struct scsi_device *, u8 page, unsigned char *buf,
int buf_len);
extern int scsi_device_set_state(struct scsi_device *sdev,
enum scsi_device_state state);
extern struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
gfp_t gfpflags);
extern void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt);
extern void sdev_evt_send_simple(struct scsi_device *sdev,
enum scsi_device_event evt_type, gfp_t gfpflags);
extern int scsi_device_quiesce(struct scsi_device *sdev);
extern void scsi_device_resume(struct scsi_device *sdev);
extern void scsi_target_quiesce(struct scsi_target *);
extern void scsi_target_resume(struct scsi_target *);
extern void scsi_scan_target(struct device *parent, unsigned int channel,
unsigned int id, unsigned int lun, int rescan);
extern void scsi_target_reap(struct scsi_target *);
extern void scsi_target_block(struct device *);
extern void scsi_target_unblock(struct device *);
extern void scsi_remove_target(struct device *);
extern void int_to_scsilun(unsigned int, struct scsi_lun *);
extern int scsilun_to_int(struct scsi_lun *);
extern const char *scsi_device_state_name(enum scsi_device_state);
extern int scsi_is_sdev_device(const struct device *);
extern int scsi_is_target_device(const struct device *);
extern int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
int data_direction, void *buffer, unsigned bufflen,
unsigned char *sense, int timeout, int retries,
int flag, int *resid);
extern int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
int data_direction, void *buffer, unsigned bufflen,
struct scsi_sense_hdr *, int timeout, int retries,
int *resid);
#ifdef CONFIG_PM_RUNTIME
extern int scsi_autopm_get_device(struct scsi_device *);
extern void scsi_autopm_put_device(struct scsi_device *);
#else
static inline int scsi_autopm_get_device(struct scsi_device *d) { return 0; }
static inline void scsi_autopm_put_device(struct scsi_device *d) {}
#endif /* CONFIG_PM_RUNTIME */
static inline int __must_check scsi_device_reprobe(struct scsi_device *sdev)
{
return device_reprobe(&sdev->sdev_gendev);
}
static inline unsigned int sdev_channel(struct scsi_device *sdev)
{
return sdev->channel;
}
static inline unsigned int sdev_id(struct scsi_device *sdev)
{
return sdev->id;
}
#define scmd_id(scmd) sdev_id((scmd)->device)
#define scmd_channel(scmd) sdev_channel((scmd)->device)
/*
* checks for positions of the SCSI state machine
*/
static inline int scsi_device_online(struct scsi_device *sdev)
{
return (sdev->sdev_state != SDEV_OFFLINE &&
sdev->sdev_state != SDEV_DEL);
}
static inline int scsi_device_blocked(struct scsi_device *sdev)
{
return sdev->sdev_state == SDEV_BLOCK ||
sdev->sdev_state == SDEV_CREATED_BLOCK;
}
static inline int scsi_device_created(struct scsi_device *sdev)
{
return sdev->sdev_state == SDEV_CREATED ||
sdev->sdev_state == SDEV_CREATED_BLOCK;
}
/* accessor functions for the SCSI parameters */
static inline int scsi_device_sync(struct scsi_device *sdev)
{
return sdev->sdtr;
}
static inline int scsi_device_wide(struct scsi_device *sdev)
{
return sdev->wdtr;
}
static inline int scsi_device_dt(struct scsi_device *sdev)
{
return sdev->ppr;
}
static inline int scsi_device_dt_only(struct scsi_device *sdev)
{
if (sdev->inquiry_len < 57)
return 0;
return (sdev->inquiry[56] & 0x0c) == 0x04;
}
static inline int scsi_device_ius(struct scsi_device *sdev)
{
if (sdev->inquiry_len < 57)
return 0;
return sdev->inquiry[56] & 0x01;
}
static inline int scsi_device_qas(struct scsi_device *sdev)
{
if (sdev->inquiry_len < 57)
return 0;
return sdev->inquiry[56] & 0x02;
}
static inline int scsi_device_enclosure(struct scsi_device *sdev)
{
return sdev->inquiry ? (sdev->inquiry[6] & (1<<6)) : 1;
}
static inline int scsi_device_protection(struct scsi_device *sdev)
{
return sdev->scsi_level > SCSI_2 && sdev->inquiry[5] & (1<<0);
}
#define MODULE_ALIAS_SCSI_DEVICE(type) \
MODULE_ALIAS("scsi:t-" __stringify(type) "*")
#define SCSI_DEVICE_MODALIAS_FMT "scsi:t-0x%02x"
#endif /* _SCSI_SCSI_DEVICE_H */
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