| BUFQ(9) | Kernel Developer's Manual | BUFQ(9) | 
bufq, bufq_init,
  bufq_register,
  bufq_unregister, bufq_state,
  bufq_alloc, bufq_drain,
  bufq_free,
  bufq_getstrategyname,
  bufq_move, bufq_put,
  bufq_get, bufq_peek,
  bufq_cancel —
#include <sys/bufq.h>
void
  
  bufq_init(void);
int
  
  bufq_register(struct
    bufq_strat *);
int
  
  bufq_unregister(struct
    bufq_strat *);
int
  
  bufq_alloc(struct
    bufq_state **bufq, const
    char *strategy, int
    flags);
void
  
  bufq_drain(struct
    bufq_state *bufq);
void
  
  bufq_free(struct
    bufq_state *bufq);
const char *
  
  bufq_getstrategyname(struct
    bufq_state *bufq);
void
  
  bufq_move(struct
    bufq_state *dst, struct
    bufq_state *src);
void
  
  bufq_put(struct
    bufq_state *bufq, struct
    buf *bp);
struct buf *
  
  bufq_get(struct
    bufq_state *bufq);
struct buf *
  
  bufq_peek(struct
    bufq_state *bufq);
struct buf *
  
  bufq_cancel(struct
    bufq_state *bufq, struct
    buf *bp);
bufq subsystem is a set of operations for the
  management of device buffer queues. Various strategies for ordering of entries
  in the buffer queues can be provided by loadable kernel modules (see
  module(9)). By default, the
  BUFQ_FCFS and BUFQ_DISKSORT
  strategies are included in the kernel; see
  options(4) for more details.
The primary data type for using the operations is the bufq_state structure, which is opaque for users. Each buffer queue strategy module is defined by the bufq_strat structure, which is also opaque for users.
bufq_init(void)bufq subsystem. This routine must
      be called before any other bufq routines.bufq_register(bs)bufq_unregister(bs)bufq_alloc() below).bufq_alloc(bufq,
    strategy, flags)The argument strategy specifies a buffer queue strategy to be used for this buffer queue. The following special values can be used:
BUFQ_STRAT_ANYbufq_alloc() select a strategy.BUFQ_DISK_DEFAULT_STRATbufq_alloc() select a strategy, assuming
          it will be used for a normal disk device.Valid bits for the flags are:
BUFQ_SORT_RAWBLOCKBUFQ_SORT_CYLINDERBUFQ_EXACTENOENT. If this flag is not specified,
          bufq_alloc() will silently use one of
          available strategies.If a specific strategy is specified but not currently
        available, the bufq subsystem will attempt to
        auto-load the corresponding kernel module using
        module_autoload(9).
bufq_drain(bufq)bufq_free(bufq)bufq_getstrategyname(bufq)bufq_move(dst,
    src)bufq_put(bufq,
    bp)bufq_get(bufq)NULL if the queue is empty.bufq_peek(bufq)bufq_get(),
      bufq_put(), or
      bufq_drain() is called. Returns
      NULL if the queue is empty.bufq_cancel(bufq,
    bp)NULL if the element can not be found on
      the queue or bp if it has been found and removed.
      This operation can be computationally expensive if there are a lot of
      buffers queued.bufq subsystem appeared in NetBSD
  2.0.
bufq subsystem was written by
  Jürgen Hannken-Illjes
  ⟨hannken@NetBSD.org⟩.
| November 17, 2016 | NetBSD 9.3 |