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target: use a workqueue for I/O completions

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Instead of abusing the target processing thread for offloading I/O
completion in the backends to user context add a new workqueue.  This means
completions can be processed as fast as available CPU time allows it,
including in parallel with other completions and more importantly I/O
submission or QUEUE FULL retries.  This should give much better performance
especially on loaded systems.

As a fallout we can merge all the completed states into a single
one.

On the downside this change complicates lun reset handling a bit by
requiring us to cancel a work item only for those states that have it
initialized.  The alternative would be to either always initialize the work
item to a dummy handler, or always use the same handler and do a switch on
the state. The long term solution will be a flag that says that the command
has an initialized work item, but that's only going to be useful once we
have more users.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Christoph Hellwig 2011-10-17 13:56:53 -04:00 committed by Nicholas Bellinger
parent 59aaad1ec4
commit 35e0e75753
3 changed files with 98 additions and 83 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
drivers/target/target_core_tmr.c
View File

@ -255,6 +255,16 @@ static void core_tmr_drain_task_list(
atomic_read(&cmd->t_transport_stop),
atomic_read(&cmd->t_transport_sent));
/*
* If the command may be queued onto a workqueue cancel it now.
*
* This is equivalent to removal from the execute queue in the
* loop above, but we do it down here given that
* cancel_work_sync may block.
*/
if (cmd->t_state == TRANSPORT_COMPLETE)
cancel_work_sync(&cmd->work);
spin_lock_irqsave(&cmd->t_state_lock, flags);
target_stop_task(task, &flags);

165
drivers/target/target_core_transport.c
View File

@ -58,6 +58,7 @@
static int sub_api_initialized;
static struct workqueue_struct *target_completion_wq;
static struct kmem_cache *se_cmd_cache;
static struct kmem_cache *se_sess_cache;
struct kmem_cache *se_tmr_req_cache;
@ -84,6 +85,8 @@ static int transport_generic_get_mem(struct se_cmd *cmd);
static void transport_put_cmd(struct se_cmd *cmd);
static void transport_remove_cmd_from_queue(struct se_cmd *cmd);
static int transport_set_sense_codes(struct se_cmd *cmd, u8 asc, u8 ascq);
static void transport_generic_request_failure(struct se_cmd *, int, int);
static void target_complete_ok_work(struct work_struct *work);
int init_se_kmem_caches(void)
{
@ -99,7 +102,7 @@ int init_se_kmem_caches(void)
if (!se_tmr_req_cache) {
pr_err("kmem_cache_create() for struct se_tmr_req"
" failed\n");
goto out;
goto out_free_cmd_cache;
}
se_sess_cache = kmem_cache_create("se_sess_cache",
sizeof(struct se_session), __alignof__(struct se_session),
@ -107,14 +110,14 @@ int init_se_kmem_caches(void)
if (!se_sess_cache) {
pr_err("kmem_cache_create() for struct se_session"
" failed\n");
goto out;
goto out_free_tmr_req_cache;
}
se_ua_cache = kmem_cache_create("se_ua_cache",
sizeof(struct se_ua), __alignof__(struct se_ua),
0, NULL);
if (!se_ua_cache) {
pr_err("kmem_cache_create() for struct se_ua failed\n");
goto out;
goto out_free_sess_cache;
}
t10_pr_reg_cache = kmem_cache_create("t10_pr_reg_cache",
sizeof(struct t10_pr_registration),
@ -122,7 +125,7 @@ int init_se_kmem_caches(void)
if (!t10_pr_reg_cache) {
pr_err("kmem_cache_create() for struct t10_pr_registration"
" failed\n");
goto out;
goto out_free_ua_cache;
}
t10_alua_lu_gp_cache = kmem_cache_create("t10_alua_lu_gp_cache",
sizeof(struct t10_alua_lu_gp), __alignof__(struct t10_alua_lu_gp),
@ -130,7 +133,7 @@ int init_se_kmem_caches(void)
if (!t10_alua_lu_gp_cache) {
pr_err("kmem_cache_create() for t10_alua_lu_gp_cache"
" failed\n");
goto out;
goto out_free_pr_reg_cache;
}
t10_alua_lu_gp_mem_cache = kmem_cache_create("t10_alua_lu_gp_mem_cache",
sizeof(struct t10_alua_lu_gp_member),
@ -138,7 +141,7 @@ int init_se_kmem_caches(void)
if (!t10_alua_lu_gp_mem_cache) {
pr_err("kmem_cache_create() for t10_alua_lu_gp_mem_"
"cache failed\n");
goto out;
goto out_free_lu_gp_cache;
}
t10_alua_tg_pt_gp_cache = kmem_cache_create("t10_alua_tg_pt_gp_cache",
sizeof(struct t10_alua_tg_pt_gp),
@ -146,7 +149,7 @@ int init_se_kmem_caches(void)
if (!t10_alua_tg_pt_gp_cache) {
pr_err("kmem_cache_create() for t10_alua_tg_pt_gp_"
"cache failed\n");
goto out;
goto out_free_lu_gp_mem_cache;
}
t10_alua_tg_pt_gp_mem_cache = kmem_cache_create(
"t10_alua_tg_pt_gp_mem_cache",
@ -156,34 +159,41 @@ int init_se_kmem_caches(void)
if (!t10_alua_tg_pt_gp_mem_cache) {
pr_err("kmem_cache_create() for t10_alua_tg_pt_gp_"
"mem_t failed\n");
goto out;
goto out_free_tg_pt_gp_cache;
}
target_completion_wq = alloc_workqueue("target_completion",
WQ_MEM_RECLAIM, 0);
if (!target_completion_wq)
goto out_free_tg_pt_gp_mem_cache;
return 0;
out_free_tg_pt_gp_mem_cache:
kmem_cache_destroy(t10_alua_tg_pt_gp_mem_cache);
out_free_tg_pt_gp_cache:
kmem_cache_destroy(t10_alua_tg_pt_gp_cache);
out_free_lu_gp_mem_cache:
kmem_cache_destroy(t10_alua_lu_gp_mem_cache);
out_free_lu_gp_cache:
kmem_cache_destroy(t10_alua_lu_gp_cache);
out_free_pr_reg_cache:
kmem_cache_destroy(t10_pr_reg_cache);
out_free_ua_cache:
kmem_cache_destroy(se_ua_cache);
out_free_sess_cache:
kmem_cache_destroy(se_sess_cache);
out_free_tmr_req_cache:
kmem_cache_destroy(se_tmr_req_cache);
out_free_cmd_cache:
kmem_cache_destroy(se_cmd_cache);
out:
if (se_cmd_cache)
kmem_cache_destroy(se_cmd_cache);
if (se_tmr_req_cache)
kmem_cache_destroy(se_tmr_req_cache);
if (se_sess_cache)
kmem_cache_destroy(se_sess_cache);
if (se_ua_cache)
kmem_cache_destroy(se_ua_cache);
if (t10_pr_reg_cache)
kmem_cache_destroy(t10_pr_reg_cache);
if (t10_alua_lu_gp_cache)
kmem_cache_destroy(t10_alua_lu_gp_cache);
if (t10_alua_lu_gp_mem_cache)
kmem_cache_destroy(t10_alua_lu_gp_mem_cache);
if (t10_alua_tg_pt_gp_cache)
kmem_cache_destroy(t10_alua_tg_pt_gp_cache);
if (t10_alua_tg_pt_gp_mem_cache)
kmem_cache_destroy(t10_alua_tg_pt_gp_mem_cache);
return -ENOMEM;
}
void release_se_kmem_caches(void)
{
destroy_workqueue(target_completion_wq);
kmem_cache_destroy(se_cmd_cache);
kmem_cache_destroy(se_tmr_req_cache);
kmem_cache_destroy(se_sess_cache);
@ -689,6 +699,33 @@ void transport_complete_sync_cache(struct se_cmd *cmd, int good)
}
EXPORT_SYMBOL(transport_complete_sync_cache);
static void target_complete_timeout_work(struct work_struct *work)
{
struct se_cmd *cmd = container_of(work, struct se_cmd, work);
unsigned long flags;
/*
* Reset cmd->t_se_count to allow transport_put_cmd()
* to allow last call to free memory resources.
*/
spin_lock_irqsave(&cmd->t_state_lock, flags);
if (atomic_read(&cmd->t_transport_timeout) > 1) {
int tmp = (atomic_read(&cmd->t_transport_timeout) - 1);
atomic_sub(tmp, &cmd->t_se_count);
}
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
transport_put_cmd(cmd);
}
static void target_complete_failure_work(struct work_struct *work)
{
struct se_cmd *cmd = container_of(work, struct se_cmd, work);
transport_generic_request_failure(cmd, 1, 1);
}
/* transport_complete_task():
*
* Called from interrupt and non interrupt context depending
@ -698,7 +735,6 @@ void transport_complete_task(struct se_task *task, int success)
{
struct se_cmd *cmd = task->task_se_cmd;
struct se_device *dev = cmd->se_dev;
int t_state;
unsigned long flags;
#if 0
pr_debug("task: %p CDB: 0x%02x obj_ptr: %p\n", task,
@ -749,17 +785,12 @@ void transport_complete_task(struct se_task *task, int success)
* the processing thread.
*/
if (task->task_flags & TF_TIMEOUT) {
if (!atomic_dec_and_test(
&cmd->t_task_cdbs_timeout_left)) {
spin_unlock_irqrestore(&cmd->t_state_lock,
flags);
if (!atomic_dec_and_test(&cmd->t_task_cdbs_timeout_left)) {
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
return;
}
t_state = TRANSPORT_COMPLETE_TIMEOUT;
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
transport_add_cmd_to_queue(cmd, t_state, false);
return;
INIT_WORK(&cmd->work, target_complete_timeout_work);
goto out_queue;
}
atomic_dec(&cmd->t_task_cdbs_timeout_left);
@ -769,28 +800,29 @@ void transport_complete_task(struct se_task *task, int success)
* device queue depending upon int success.
*/
if (!atomic_dec_and_test(&cmd->t_task_cdbs_left)) {
if (!success)
cmd->t_tasks_failed = 1;
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
return;
}
if (!success || cmd->t_tasks_failed) {
t_state = TRANSPORT_COMPLETE_FAILURE;
if (!task->task_error_status) {
task->task_error_status =
PYX_TRANSPORT_UNKNOWN_SAM_OPCODE;
cmd->transport_error_status =
PYX_TRANSPORT_UNKNOWN_SAM_OPCODE;
}
INIT_WORK(&cmd->work, target_complete_failure_work);
} else {
atomic_set(&cmd->t_transport_complete, 1);
t_state = TRANSPORT_COMPLETE_OK;
INIT_WORK(&cmd->work, target_complete_ok_work);
}
out_queue:
cmd->t_state = TRANSPORT_COMPLETE;
atomic_set(&cmd->t_transport_active, 1);
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
transport_add_cmd_to_queue(cmd, t_state, false);
queue_work(target_completion_wq, &cmd->work);
}
EXPORT_SYMBOL(transport_complete_task);
@ -1642,8 +1674,6 @@ int transport_generic_allocate_tasks(
}
EXPORT_SYMBOL(transport_generic_allocate_tasks);
static void transport_generic_request_failure(struct se_cmd *, int, int);
/*
* Used by fabric module frontends to queue tasks directly.
* Many only be used from process context only
@ -1985,25 +2015,6 @@ static void transport_direct_request_timeout(struct se_cmd *cmd)
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
}
static void transport_generic_request_timeout(struct se_cmd *cmd)
{
unsigned long flags;
/*
* Reset cmd->t_se_count to allow transport_put_cmd()
* to allow last call to free memory resources.
*/
spin_lock_irqsave(&cmd->t_state_lock, flags);
if (atomic_read(&cmd->t_transport_timeout) > 1) {
int tmp = (atomic_read(&cmd->t_transport_timeout) - 1);
atomic_sub(tmp, &cmd->t_se_count);
}
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
transport_put_cmd(cmd);
}
static inline u32 transport_lba_21(unsigned char *cdb)
{
return ((cdb[1] & 0x1f) << 16) | (cdb[2] << 8) | cdb[3];
@ -2094,10 +2105,12 @@ static void transport_task_timeout_handler(unsigned long data)
pr_debug("transport task: %p cmd: %p timeout ZERO t_task_cdbs_left\n",
task, cmd);
cmd->t_state = TRANSPORT_COMPLETE_FAILURE;
INIT_WORK(&cmd->work, target_complete_failure_work);
cmd->t_state = TRANSPORT_COMPLETE;
atomic_set(&cmd->t_transport_active, 1);
spin_unlock_irqrestore(&cmd->t_state_lock, flags);
transport_add_cmd_to_queue(cmd, TRANSPORT_COMPLETE_FAILURE, false);
queue_work(target_completion_wq, &cmd->work);
}
static void transport_start_task_timer(struct se_task *task)
@ -2879,7 +2892,7 @@ static int transport_generic_cmd_sequencer(
if (passthrough)
break;
/*
* Setup BIDI XOR callback to be run during transport_generic_complete_ok()
* Setup BIDI XOR callback to be run after I/O completion.
*/
cmd->transport_complete_callback = &transport_xor_callback;
cmd->t_tasks_fua = (cdb[1] & 0x8);
@ -2913,8 +2926,8 @@ static int transport_generic_cmd_sequencer(
break;
/*
* Setup BIDI XOR callback to be run during
* transport_generic_complete_ok()
* Setup BIDI XOR callback to be run during after I/O
* completion.
*/
cmd->transport_complete_callback = &transport_xor_callback;
cmd->t_tasks_fua = (cdb[10] & 0x8);
@ -3311,8 +3324,7 @@ out_invalid_cdb_field:
}
/*
* Called from transport_generic_complete_ok() and
* transport_generic_request_failure() to determine which dormant/delayed
* Called from I/O completion to determine which dormant/delayed
* and ordered cmds need to have their tasks added to the execution queue.
*/
static void transport_complete_task_attr(struct se_cmd *cmd)
@ -3433,9 +3445,11 @@ static void transport_handle_queue_full(
schedule_work(&cmd->se_dev->qf_work_queue);
}
static void transport_generic_complete_ok(struct se_cmd *cmd)
static void target_complete_ok_work(struct work_struct *work)
{
struct se_cmd *cmd = container_of(work, struct se_cmd, work);
int reason = 0, ret;
/*
* Check if we need to move delayed/dormant tasks from cmds on the
* delayed execution list after a HEAD_OF_QUEUE or ORDERED Task
@ -4778,21 +4792,12 @@ get_cmd:
case TRANSPORT_PROCESS_WRITE:
transport_generic_process_write(cmd);
break;
case TRANSPORT_COMPLETE_OK:
transport_generic_complete_ok(cmd);
break;
case TRANSPORT_FREE_CMD_INTR:
transport_generic_free_cmd(cmd, 0);
break;
case TRANSPORT_PROCESS_TMR:
transport_generic_do_tmr(cmd);
break;
case TRANSPORT_COMPLETE_FAILURE:
transport_generic_request_failure(cmd, 1, 1);
break;
case TRANSPORT_COMPLETE_TIMEOUT:
transport_generic_request_timeout(cmd);
break;
case TRANSPORT_COMPLETE_QF_WP:
transport_write_pending_qf(cmd);
break;

6
include/target/target_core_base.h
View File

@ -86,9 +86,7 @@ enum transport_state_table {
TRANSPORT_WRITE_PENDING = 3,
TRANSPORT_PROCESS_WRITE = 4,
TRANSPORT_PROCESSING = 5,
TRANSPORT_COMPLETE_OK = 6,
TRANSPORT_COMPLETE_FAILURE = 7,
TRANSPORT_COMPLETE_TIMEOUT = 8,
TRANSPORT_COMPLETE = 6,
TRANSPORT_PROCESS_TMR = 9,
TRANSPORT_ISTATE_PROCESSING = 11,
TRANSPORT_NEW_CMD_MAP = 16,
@ -492,6 +490,8 @@ struct se_cmd {
struct completion transport_lun_stop_comp;
struct scatterlist *t_tasks_sg_chained;
struct work_struct work;
/*
* Used for pre-registered fabric SGL passthrough WRITE and READ
* with the special SCF_PASSTHROUGH_CONTIG_TO_SG case for TCM_Loop