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linux-stable/include/linux/blk-iopoll.h

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block: add blk-iopoll, a NAPI like approach for block devices This borrows some code from NAPI and implements a polled completion mode for block devices. The idea is the same as NAPI - instead of doing the command completion when the irq occurs, schedule a dedicated softirq in the hopes that we will complete more IO when the iopoll handler is invoked. Devices have a budget of commands assigned, and will stay in polled mode as long as they continue to consume their budget from the iopoll softirq handler. If they do not, the device is set back to interrupt completion mode. This patch holds the core bits for blk-iopoll, device driver support sold separately. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-08-05 07:07:21 +00:00
#ifndef BLK_IOPOLL_H
#define BLK_IOPOLL_H
struct blk_iopoll;
typedef int (blk_iopoll_fn)(struct blk_iopoll *, int);
struct blk_iopoll {
struct list_head list;
unsigned long state;
unsigned long data;
int weight;
int max;
blk_iopoll_fn *poll;
};
enum {
IOPOLL_F_SCHED = 0,
IOPOLL_F_DISABLE = 1,
};
block: make blk_iopoll_prep_sched() follow normal 0/1 return convention Return 0 if we successfully marked this iopoll structure as ours for scheduling, instead of 1. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-08-11 06:31:14 +00:00
/*
* Returns 0 if we successfully set the IOPOLL_F_SCHED bit, indicating
* that we were the first to acquire this iop for scheduling. If this iop
* is currently disabled, return "failure".
*/
block: add blk-iopoll, a NAPI like approach for block devices This borrows some code from NAPI and implements a polled completion mode for block devices. The idea is the same as NAPI - instead of doing the command completion when the irq occurs, schedule a dedicated softirq in the hopes that we will complete more IO when the iopoll handler is invoked. Devices have a budget of commands assigned, and will stay in polled mode as long as they continue to consume their budget from the iopoll softirq handler. If they do not, the device is set back to interrupt completion mode. This patch holds the core bits for blk-iopoll, device driver support sold separately. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-08-05 07:07:21 +00:00
static inline int blk_iopoll_sched_prep(struct blk_iopoll *iop)
{
block: make blk_iopoll_prep_sched() follow normal 0/1 return convention Return 0 if we successfully marked this iopoll structure as ours for scheduling, instead of 1. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-08-11 06:31:14 +00:00
if (!test_bit(IOPOLL_F_DISABLE, &iop->state))
return test_and_set_bit(IOPOLL_F_SCHED, &iop->state);
return 1;
block: add blk-iopoll, a NAPI like approach for block devices This borrows some code from NAPI and implements a polled completion mode for block devices. The idea is the same as NAPI - instead of doing the command completion when the irq occurs, schedule a dedicated softirq in the hopes that we will complete more IO when the iopoll handler is invoked. Devices have a budget of commands assigned, and will stay in polled mode as long as they continue to consume their budget from the iopoll softirq handler. If they do not, the device is set back to interrupt completion mode. This patch holds the core bits for blk-iopoll, device driver support sold separately. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-08-05 07:07:21 +00:00
}
static inline int blk_iopoll_disable_pending(struct blk_iopoll *iop)
{
return test_bit(IOPOLL_F_DISABLE, &iop->state);
}
extern void blk_iopoll_sched(struct blk_iopoll *);
extern void blk_iopoll_init(struct blk_iopoll *, int, blk_iopoll_fn *);
extern void blk_iopoll_complete(struct blk_iopoll *);
extern void __blk_iopoll_complete(struct blk_iopoll *);
extern void blk_iopoll_enable(struct blk_iopoll *);
extern void blk_iopoll_disable(struct blk_iopoll *);
extern int blk_iopoll_enabled;
#endif
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