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ioprio: move io priority from task_struct to io_context
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This is where it belongs and then it doesn't take up space for a
process that doesn't do IO.

Signed-off-by: Jens Axboe <[email protected]>
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Jens Axboe committed Jan 28, 2008
1 parent 9152530 commit fd0928d
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Showing 9 changed files with 178 additions and 122 deletions.
34 changes: 16 additions & 18 deletions block/cfq-iosched.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -199,7 +199,7 @@ CFQ_CFQQ_FNS(sync);

static void cfq_dispatch_insert(struct request_queue *, struct request *);
static struct cfq_queue *cfq_get_queue(struct cfq_data *, int,
struct task_struct *, gfp_t);
struct io_context *, gfp_t);
static struct cfq_io_context *cfq_cic_rb_lookup(struct cfq_data *,
struct io_context *);

Expand Down Expand Up @@ -1273,15 +1273,15 @@ cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
return cic;
}

static void cfq_init_prio_data(struct cfq_queue *cfqq)
static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
{
struct task_struct *tsk = current;
int ioprio_class;

if (!cfq_cfqq_prio_changed(cfqq))
return;

ioprio_class = IOPRIO_PRIO_CLASS(tsk->ioprio);
ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
switch (ioprio_class) {
default:
printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
Expand All @@ -1293,11 +1293,11 @@ static void cfq_init_prio_data(struct cfq_queue *cfqq)
cfqq->ioprio_class = IOPRIO_CLASS_BE;
break;
case IOPRIO_CLASS_RT:
cfqq->ioprio = task_ioprio(tsk);
cfqq->ioprio = task_ioprio(ioc);
cfqq->ioprio_class = IOPRIO_CLASS_RT;
break;
case IOPRIO_CLASS_BE:
cfqq->ioprio = task_ioprio(tsk);
cfqq->ioprio = task_ioprio(ioc);
cfqq->ioprio_class = IOPRIO_CLASS_BE;
break;
case IOPRIO_CLASS_IDLE:
Expand Down Expand Up @@ -1330,8 +1330,7 @@ static inline void changed_ioprio(struct cfq_io_context *cic)
cfqq = cic->cfqq[ASYNC];
if (cfqq) {
struct cfq_queue *new_cfqq;
new_cfqq = cfq_get_queue(cfqd, ASYNC, cic->ioc->task,
GFP_ATOMIC);
new_cfqq = cfq_get_queue(cfqd, ASYNC, cic->ioc, GFP_ATOMIC);
if (new_cfqq) {
cic->cfqq[ASYNC] = new_cfqq;
cfq_put_queue(cfqq);
Expand Down Expand Up @@ -1363,13 +1362,13 @@ static void cfq_ioc_set_ioprio(struct io_context *ioc)

static struct cfq_queue *
cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync,
struct task_struct *tsk, gfp_t gfp_mask)
struct io_context *ioc, gfp_t gfp_mask)
{
struct cfq_queue *cfqq, *new_cfqq = NULL;
struct cfq_io_context *cic;

retry:
cic = cfq_cic_rb_lookup(cfqd, tsk->io_context);
cic = cfq_cic_rb_lookup(cfqd, ioc);
/* cic always exists here */
cfqq = cic_to_cfqq(cic, is_sync);

Expand Down Expand Up @@ -1412,7 +1411,7 @@ cfq_find_alloc_queue(struct cfq_data *cfqd, int is_sync,
cfq_mark_cfqq_prio_changed(cfqq);
cfq_mark_cfqq_queue_new(cfqq);

cfq_init_prio_data(cfqq);
cfq_init_prio_data(cfqq, ioc);
}

if (new_cfqq)
Expand All @@ -1439,11 +1438,11 @@ cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
}

static struct cfq_queue *
cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct task_struct *tsk,
cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc,
gfp_t gfp_mask)
{
const int ioprio = task_ioprio(tsk);
const int ioprio_class = task_ioprio_class(tsk);
const int ioprio = task_ioprio(ioc);
const int ioprio_class = task_ioprio_class(ioc);
struct cfq_queue **async_cfqq = NULL;
struct cfq_queue *cfqq = NULL;

Expand All @@ -1453,7 +1452,7 @@ cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct task_struct *tsk,
}

if (!cfqq) {
cfqq = cfq_find_alloc_queue(cfqd, is_sync, tsk, gfp_mask);
cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
if (!cfqq)
return NULL;
}
Expand Down Expand Up @@ -1793,7 +1792,7 @@ static void cfq_insert_request(struct request_queue *q, struct request *rq)
struct cfq_data *cfqd = q->elevator->elevator_data;
struct cfq_queue *cfqq = RQ_CFQQ(rq);

cfq_init_prio_data(cfqq);
cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);

cfq_add_rq_rb(rq);

Expand Down Expand Up @@ -1900,7 +1899,7 @@ static int cfq_may_queue(struct request_queue *q, int rw)

cfqq = cic_to_cfqq(cic, rw & REQ_RW_SYNC);
if (cfqq) {
cfq_init_prio_data(cfqq);
cfq_init_prio_data(cfqq, cic->ioc);
cfq_prio_boost(cfqq);

return __cfq_may_queue(cfqq);
Expand Down Expand Up @@ -1938,7 +1937,6 @@ static int
cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
struct task_struct *tsk = current;
struct cfq_io_context *cic;
const int rw = rq_data_dir(rq);
const int is_sync = rq_is_sync(rq);
Expand All @@ -1956,7 +1954,7 @@ cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)

cfqq = cic_to_cfqq(cic, is_sync);
if (!cfqq) {
cfqq = cfq_get_queue(cfqd, is_sync, tsk, gfp_mask);
cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);

if (!cfqq)
goto queue_fail;
Expand Down
30 changes: 21 additions & 9 deletions block/ll_rw_blk.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3904,6 +3904,26 @@ void exit_io_context(void)
put_io_context(ioc);
}

struct io_context *alloc_io_context(gfp_t gfp_flags, int node)
{
struct io_context *ret;

ret = kmem_cache_alloc_node(iocontext_cachep, gfp_flags, node);
if (ret) {
atomic_set(&ret->refcount, 1);
ret->task = current;
ret->ioprio_changed = 0;
ret->ioprio = 0;
ret->last_waited = jiffies; /* doesn't matter... */
ret->nr_batch_requests = 0; /* because this is 0 */
ret->aic = NULL;
ret->cic_root.rb_node = NULL;
ret->ioc_data = NULL;
}

return ret;
}

/*
* If the current task has no IO context then create one and initialise it.
* Otherwise, return its existing IO context.
Expand All @@ -3921,16 +3941,8 @@ static struct io_context *current_io_context(gfp_t gfp_flags, int node)
if (likely(ret))
return ret;

ret = kmem_cache_alloc_node(iocontext_cachep, gfp_flags, node);
ret = alloc_io_context(gfp_flags, node);
if (ret) {
atomic_set(&ret->refcount, 1);
ret->task = current;
ret->ioprio_changed = 0;
ret->last_waited = jiffies; /* doesn't matter... */
ret->nr_batch_requests = 0; /* because this is 0 */
ret->aic = NULL;
ret->cic_root.rb_node = NULL;
ret->ioc_data = NULL;
/* make sure set_task_ioprio() sees the settings above */
smp_wmb();
tsk->io_context = ret;
Expand Down
29 changes: 21 additions & 8 deletions fs/ioprio.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -41,18 +41,29 @@ static int set_task_ioprio(struct task_struct *task, int ioprio)
return err;

task_lock(task);
do {
ioc = task->io_context;
/* see wmb() in current_io_context() */
smp_read_barrier_depends();
if (ioc)
break;

task->ioprio = ioprio;

ioc = task->io_context;
/* see wmb() in current_io_context() */
smp_read_barrier_depends();
ioc = alloc_io_context(GFP_ATOMIC, -1);
if (!ioc) {
err = -ENOMEM;
break;
}
task->io_context = ioc;
ioc->task = task;
} while (1);

if (ioc)
if (!err) {
ioc->ioprio = ioprio;
ioc->ioprio_changed = 1;
}

task_unlock(task);
return 0;
return err;
}

asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
Expand Down Expand Up @@ -148,7 +159,9 @@ static int get_task_ioprio(struct task_struct *p)
ret = security_task_getioprio(p);
if (ret)
goto out;
ret = p->ioprio;
ret = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM);
if (p->io_context)
ret = p->io_context->ioprio;
out:
return ret;
}
Expand Down
81 changes: 7 additions & 74 deletions include/linux/blkdev.h
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Original file line number Diff line number Diff line change
Expand Up @@ -34,83 +34,10 @@ struct sg_io_hdr;
#define BLKDEV_MIN_RQ 4
#define BLKDEV_MAX_RQ 128 /* Default maximum */

/*
* This is the per-process anticipatory I/O scheduler state.
*/
struct as_io_context {
spinlock_t lock;

void (*dtor)(struct as_io_context *aic); /* destructor */
void (*exit)(struct as_io_context *aic); /* called on task exit */

unsigned long state;
atomic_t nr_queued; /* queued reads & sync writes */
atomic_t nr_dispatched; /* number of requests gone to the drivers */

/* IO History tracking */
/* Thinktime */
unsigned long last_end_request;
unsigned long ttime_total;
unsigned long ttime_samples;
unsigned long ttime_mean;
/* Layout pattern */
unsigned int seek_samples;
sector_t last_request_pos;
u64 seek_total;
sector_t seek_mean;
};

struct cfq_queue;
struct cfq_io_context {
struct rb_node rb_node;
void *key;

struct cfq_queue *cfqq[2];

struct io_context *ioc;

unsigned long last_end_request;
sector_t last_request_pos;

unsigned long ttime_total;
unsigned long ttime_samples;
unsigned long ttime_mean;

unsigned int seek_samples;
u64 seek_total;
sector_t seek_mean;

struct list_head queue_list;

void (*dtor)(struct io_context *); /* destructor */
void (*exit)(struct io_context *); /* called on task exit */
};

/*
* This is the per-process I/O subsystem state. It is refcounted and
* kmalloc'ed. Currently all fields are modified in process io context
* (apart from the atomic refcount), so require no locking.
*/
struct io_context {
atomic_t refcount;
struct task_struct *task;

unsigned int ioprio_changed;

/*
* For request batching
*/
unsigned long last_waited; /* Time last woken after wait for request */
int nr_batch_requests; /* Number of requests left in the batch */

struct as_io_context *aic;
struct rb_root cic_root;
void *ioc_data;
};

void put_io_context(struct io_context *ioc);
void exit_io_context(void);
struct io_context *get_io_context(gfp_t gfp_flags, int node);
struct io_context *alloc_io_context(gfp_t gfp_flags, int node);
void copy_io_context(struct io_context **pdst, struct io_context **psrc);
void swap_io_context(struct io_context **ioc1, struct io_context **ioc2);

Expand Down Expand Up @@ -894,6 +821,12 @@ static inline void exit_io_context(void)
{
}

static inline int put_io_context(struct io_context *ioc)
{
return 1;
}


#endif /* CONFIG_BLOCK */

#endif
1 change: 0 additions & 1 deletion include/linux/init_task.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -137,7 +137,6 @@ extern struct group_info init_groups;
.time_slice = HZ, \
.nr_cpus_allowed = NR_CPUS, \
}, \
.ioprio = 0, \
.tasks = LIST_HEAD_INIT(tsk.tasks), \
.ptrace_children= LIST_HEAD_INIT(tsk.ptrace_children), \
.ptrace_list = LIST_HEAD_INIT(tsk.ptrace_list), \
Expand Down
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