Provided by: libfabric-dev_1.6.2-3_amd64 bug

NAME

       fi_eq - Event queue operations

       fi_eq_open / fi_close : Open/close an event queue

       fi_control : Control operation of EQ

       fi_eq_read / fi_eq_readerr : Read an event from an event queue

       fi_eq_write : Writes an event to an event queue

       fi_eq_sread : A synchronous (blocking) read of an event queue

       fi_eq_strerror : Converts provider specific error information into a printable string

SYNOPSIS

              #include <rdma/fi_domain.h>

              int fi_eq_open(struct fid_fabric *fabric, struct fi_eq_attr *attr,
                  struct fid_eq **eq, void *context);

              int fi_close(struct fid *eq);

              int fi_control(struct fid *eq, int command, void *arg);

              ssize_t fi_eq_read(struct fid_eq *eq, uint32_t *event,
                  void *buf, size_t len, uint64_t flags);

              ssize_t fi_eq_readerr(struct fid_eq *eq, struct fi_eq_err_entry *buf,
                  uint64_t flags);

              ssize_t fi_eq_write(struct fid_eq *eq, uint32_t event,
                  const void *buf, size_t len, uint64_t flags);

              ssize_t fi_eq_sread(struct fid_eq *eq, uint32_t *event,
                  void *buf, size_t len, int timeout, uint64_t flags);

              const char * fi_eq_strerror(struct fid_eq *eq, int prov_errno,
                    const void *err_data, char *buf, size_t len);

ARGUMENTS

       fabric : Opened fabric descriptor

       eq : Event queue

       attr : Event queue attributes

       context : User specified context associated with the event queue.

       event : Reported event

       buf  : For read calls, the data buffer to write events into.  For write calls, an event to
       insert into the event  queue.   For  fi_eq_strerror,  an  optional  buffer  that  receives
       printable error information.

       len : Length of data buffer

       flags : Additional flags to apply to the operation

       command : Command of control operation to perform on EQ.

       arg : Optional control argument

       prov_errno : Provider specific error value

       err_data : Provider specific error data related to a completion

       timeout : Timeout specified in milliseconds

DESCRIPTION

       Event  queues  are  used  to  report  events associated with control operations.  They are
       associated with memory registration, address vectors, connection  management,  and  fabric
       and domain level events.  Reported events are either associated with a requested operation
       or affiliated with a call that registers for specific types of events, such  as  listening
       for connection requests.

   fi_eq_open
       fi_eq_open allocates a new event queue.

       The properties and behavior of an event queue are defined by struct fi_eq_attr.

              struct fi_eq_attr {
                  size_t               size;      /* # entries for EQ */
                  uint64_t             flags;     /* operation flags */
                  enum fi_wait_obj     wait_obj;  /* requested wait object */
                  int                  signaling_vector; /* interrupt affinity */
                  struct fid_wait     *wait_set;  /* optional wait set */
              };

       size : Specifies the minimum size of an event queue.

       flags : Flags that control the configuration of the EQ.

       · FI_WRITE  :  Indicates  that  the application requires support for inserting user events
         into the EQ.  If this flag is set, then the fi_eq_write operation must be  supported  by
         the  provider.   If  the  FI_WRITE  flag is not set, then the application may not invoke
         fi_eq_write.

       · FI_AFFINITY : Indicates that the signaling_vector field (see below) is valid.

       wait_obj : EQ's may be associated  with  a  specific  wait  object.   Wait  objects  allow
       applications  to  block  until  the  wait  object is signaled, indicating that an event is
       available to be read.  Users may use fi_control to retrieve  the  underlying  wait  object
       associated with an EQ, in order to use it in other system calls.  The following values may
       be used to specify the type of wait object associated with an EQ:

       · FI_WAIT_NONE : Used to indicate that the user will not block (wait) for  events  on  the
         EQ.   When FI_WAIT_NONE is specified, the application may not call fi_eq_sread.  This is
         the default is no wait object is specified.

       · FI_WAIT_UNSPEC : Specifies that the user will only wait on the EQ using fabric interface
         calls,  such  as fi_eq_sread.  In this case, the underlying provider may select the most
         appropriate  or  highest  performing  wait  object  available,  including  custom   wait
         mechanisms.   Applications that select FI_WAIT_UNSPEC are not guaranteed to retrieve the
         underlying wait object.

       · FI_WAIT_SET : Indicates that the event queue should use a wait set object  to  wait  for
         events.  If specified, the wait_set field must reference an existing wait set object.

       · FI_WAIT_FD  :  Indicates that the EQ should use a file descriptor as its wait mechanism.
         A file descriptor wait object must be  usable  in  select,  poll,  and  epoll  routines.
         However,  a  provider  may signal an FD wait object by marking it as readable or with an
         error.

       · FI_WAIT_MUTEX_COND : Specifies that the EQ should use a pthread mutex and cond  variable
         as a wait object.

       · FI_WAIT_CRITSEC_COND  :  Windows  specific.  Specifies that the EQ should use a critical
         section and condition variable as a wait object.

       signaling_vector : If the FI_AFFINITY flag is set, this indicates the logical  cpu  number
       (0..max  cpu - 1) that interrupts associated with the EQ should target.  This field should
       be treated as a hint to the provider and may be ignored if the provider does  not  support
       interrupt affinity.

       wait_set  :  If  wait_obj is FI_WAIT_SET, this field references a wait object to which the
       event queue should  attach.   When  an  event  is  inserted  into  the  event  queue,  the
       corresponding wait set will be signaled if all necessary conditions are met.  The use of a
       wait_set enables an optimized method of waiting for events across multiple  event  queues.
       This field is ignored if wait_obj is not FI_WAIT_SET.

   fi_close
       The fi_close call releases all resources associated with an event queue.  Any events which
       remain on the EQ when it is closed are lost.

       The EQ must not be bound to any other objects prior to being closed,  otherwise  the  call
       will return -FI_EBUSY.

   fi_control
       The  fi_control  call is used to access provider or implementation specific details of the
       event queue.  Access to the EQ should be serialized across all calls  when  fi_control  is
       invoked,  as  it  may redirect the implementation of EQ operations.  The following control
       commands are usable with an EQ.

       FI_GETWAIT (void **) : This command allows the user to retrieve the low-level wait  object
       associated  with  the  EQ.  The format of the wait-object is specified during EQ creation,
       through the EQ attributes.  The fi_control arg parameter should  be  an  address  where  a
       pointer  to  the  returned  wait  object  will  be written.  This should be an 'int *' for
       FI_WAIT_FD, or 'struct fi_mutex_cond' for FI_WAIT_MUTEX_COND.

              struct fi_mutex_cond {
                  pthread_mutex_t     *mutex;
                  pthread_cond_t      *cond;
              };

   fi_eq_read
       The fi_eq_read operations performs a non-blocking read of event data  from  the  EQ.   The
       format  of  the  event  data is based on the type of event retrieved from the EQ, with all
       events starting with a struct fi_eq_entry header.  At most one event will be returned  per
       EQ read operation.  The number of bytes successfully read from the EQ is returned from the
       read.  The FI_PEEK flag may be used to indicate that event data should be read from the EQ
       without  being consumed.  A subsequent read without the FI_PEEK flag would then remove the
       event from the EQ.

       The following types of events may be reported to an EQ, along with  information  regarding
       the format associated with each event.

       Asynchronous  Control Operations : Asynchronous control operations are basic requests that
       simply need to generate an event to indicate that they have completed.  These include  the
       following  types  of events: memory registration, address vector resolution, and multicast
       joins.

       Control requests report their completion by inserting a struct   fi_eq_entry into the  EQ.
       The format of this structure is:

              struct fi_eq_entry {
                  fid_t            fid;        /* fid associated with request */
                  void            *context;    /* operation context */
                  uint64_t         data;       /* completion-specific data */
              };

       For  the  completion  of  basic  asynchronous  control operations, the returned event will
       indicate the operation  that  has  completed,  and  the  fid  will  reference  the  fabric
       descriptor  associated  with  the  event.   For  memory  registration,  this  will  be  an
       FI_MR_COMPLETE event and the fid_mr.  Address resolution will reference an  FI_AV_COMPLETE
       event  and  fid_av.   Multicast  joins  will  report  an FI_JOIN_COMPLETE and fid_mc.  The
       context field will be set to the context specified as part of the operation, if available,
       otherwise  the context will be associated with the fabric descriptor.  The data field will
       be set as described in the man page for the corresponding object type (e.g., see  fi_av(3)
       for a description of how asynchronous address vector insertions are completed).

       Connection Notification : Connection notifications are connection management notifications
       used to setup or tear down connections between  endpoints.   There  are  three  connection
       notification  events: FI_CONNREQ, FI_CONNECTED, and FI_SHUTDOWN.  Connection notifications
       are reported using struct   fi_eq_cm_entry:

              struct fi_eq_cm_entry {
                  fid_t            fid;        /* fid associated with request */
                  struct fi_info  *info;       /* endpoint information */
                  uint8_t         data[];     /* app connection data */
              };

       A connection request (FI_CONNREQ)  event  indicates  that  a  remote  endpoint  wishes  to
       establish  a  new connection to a listening, or passive, endpoint.  The fid is the passive
       endpoint.   Information  regarding  the  requested,  active  endpoint's  capabilities  and
       attributes  are available from the info field.  The application is responsible for freeing
       this structure by calling fi_freeinfo when it is no longer needed.   The  fi_info  connreq
       field  will  reference  the  connection  request  associated with this event.  To accept a
       connection, an endpoint must first be created by passing an fi_info structure  referencing
       this  connreq  field  to  fi_endpoint().   This  endpoint is then passed to fi_accept() to
       complete the acceptance of the connection attempt.  Creating the endpoint is  most  easily
       accomplished  by  passing the fi_info returned as part of the CM event into fi_endpoint().
       If the connection is to be rejected, the connreq is passed to fi_reject().

       Any application data exchanged as part of the connection  request  is  placed  beyond  the
       fi_eq_cm_entry  structure.   The  amount  of  data  available is application dependent and
       limited to the buffer space provided by the application when fi_eq_read  is  called.   The
       amount of returned data may be calculated using the return value to fi_eq_read.  Note that
       the amount of returned data is limited by the  underlying  connection  protocol,  and  the
       length  of  any  data  returned  may  include protocol padding.  As a result, the returned
       length may be larger than that specified by the connecting peer.

       If a connection request has been accepted, an FI_CONNECTED event will be generated on both
       sides  of  the connection.  The active side -- one that called fi_connect() -- may receive
       user data as part of the FI_CONNECTED event.  The user data is passed  to  the  connection
       manager on the passive side through the fi_accept call.  User data is not provided with an
       FI_CONNECTED event on the listening side of the connection.

       Notification that a remote peer has disconnected from an active endpoint is  done  through
       the  FI_SHUTDOWN  event.   Shutdown  notification  uses  struct fi_eq_cm_entry as declared
       above.  The fid field for a shutdown notification refers to the active endpoint's fid_ep.

       Asynchronous Error Notification : Asynchronous errors are used  to  report  problems  with
       fabric  resources.   Reported  errors  may  be fatal or transient, based on the error, and
       result in the  resource  becoming  disabled.   Disabled  resources  will  fail  operations
       submitted against them until they are explicitly re-enabled by the application.

       Asynchronous  errors may be reported for completion queues and endpoints of all types.  CQ
       errors can result when resource  management  has  been  disabled,  and  the  provider  has
       detected  a  queue  overrun.   Endpoint  errors may be result of numerous actions, but are
       often associated with a failed operation.  Operations may fail because of buffer overruns,
       invalid  permissions,  incorrect  memory  access  keys,  network routing failures, network
       reach-ability issues, etc.

       Asynchronous errors are reported using struct  fi_eq_err_entry,  as  defined  below.   The
       fabric  descriptor  (fid) associated with the error is provided as part of the error data.
       An error code is also available to determine the cause of the error.

   fi_eq_sread
       The fi_eq_sread call is the  blocking  (or  synchronous)  equivalent  to  fi_eq_read.   It
       behaves  is  similar  to the non-blocking call, with the exception that the calls will not
       return until either an event has been read from the EQ or  an  error  or  timeout  occurs.
       Specifying a negative timeout means an infinite timeout.

       It  is invalid for applications to call this function if the EQ has been configured with a
       wait object of FI_WAIT_NONE or FI_WAIT_SET.

   fi_eq_readerr
       The read error function, fi_eq_readerr, retrieves information regarding  any  asynchronous
       operation  which  has completed with an unexpected error.  fi_eq_readerr is a non-blocking
       call, returning immediately whether an error completion was found or not.

       EQs are optimized to report operations  which  have  completed  successfully.   Operations
       which  fail  are  reported  'out  of  band'.   Such  operations  are  retrieved  using the
       fi_eq_readerr function.  When an operation that completes  with  an  unexpected  error  is
       inserted  into  an EQ, it is placed into a temporary error queue.  Attempting to read from
       an EQ while an item is in the error queue results in an FI_EAVAIL  failure.   Applications
       may use this return code to determine when to call fi_eq_readerr.

       Error  information  is reported to the user through struct fi_eq_err_entry.  The format of
       this structure is defined below.

              struct fi_eq_err_entry {
                  fid_t            fid;        /* fid associated with error */
                  void            *context;    /* operation context */
                  uint64_t         data;       /* completion-specific data */
                  int              err;        /* positive error code */
                  int              prov_errno; /* provider error code */
                  void            *err_data;   /* additional error data */
                  size_t           err_data_size; /* size of err_data */
              };

       The fid will reference the fabric  descriptor  associated  with  the  event.   For  memory
       registration,  this will be the fid_mr, address resolution will reference a fid_av, and CM
       events will refer to a fid_ep.  The context field will be set to the context specified  as
       part of the operation.

       The  data field will be set as described in the man page for the corresponding object type
       (e.g., see fi_av(3) for a description of how asynchronous address  vector  insertions  are
       completed).

       The  general  reason  for  the  error  is  provided  through  the  err field.  Provider or
       operational specific error information may also be available through  the  prov_errno  and
       err_data  fields.   Users  may  call  fi_eq_strerror  to  convert  provider specific error
       information into a printable string for debugging purposes.

       On input, err_data_size indicates the size of the err_data buffer in  bytes.   On  output,
       err_data_size  will  be  set  to  the  number of bytes copied to the err_data buffer.  The
       err_data information is typically used with fi_eq_strerror to provide  details  about  the
       type of error that occurred.

       For  compatibility purposes, if err_data_size is 0 on input, or the fabric was opened with
       release < 1.5, err_data will be set to a data buffer owned by the provider.  The  contents
       of the buffer will remain valid until a subsequent read call against the EQ.  Applications
       must serialize access to  the  EQ  when  processing  errors  to  ensure  that  the  buffer
       referenced by err_data does not change.

EVENT FIELDS

       The  EQ entry data structures share many of the same fields.  The meanings are the same or
       similar for all EQ structure formats, with specific details described below.

       fid : This corresponds to the fabric descriptor associated with the event.   The  type  of
       fid  depends  on  the  event  being  reported.  For FI_CONNREQ this will be the fid of the
       passive endpoint.  FI_CONNECTED  and  FI_SHUTDOWN  will  reference  the  active  endpoint.
       FI_MR_COMPLETE  and  FI_AV_COMPLETE  will  refer  to  the  MR  or  AV  fabric  descriptor,
       respectively.  FI_JOIN_COMPLETE will point to the multicast descriptor returned as part of
       the  join  operation.   Applications  can  use  fid->context value to retrieve the context
       associated with the fabric descriptor.

       context : The context value is set to the context parameter specified with  the  operation
       that  generated the event.  If no context parameter is associated with the operation, this
       field will be NULL.

       data : Data is an operation specific value or set of bytes.  For connection  events,  data
       is application data exchanged as part of the connection protocol.

       err  :  This  err code is a positive fabric errno associated with an event.  The err value
       indicates the general reason for an error, if one occurred.  See fi_errno.3 for a list  of
       possible error codes.

       prov_errno  : On an error, prov_errno may contain a provider specific error code.  The use
       of this field and its meaning is provider specific.  It  is  intended  to  be  used  as  a
       debugging  aid.   See fi_eq_strerror for additional details on converting this error value
       into a human readable string.

       err_data : On an error,  err_data  may  reference  a  provider  specific  amount  of  data
       associated with an error.  The use of this field and its meaning is provider specific.  It
       is intended to be used as a debugging aid.  See fi_eq_strerror for additional  details  on
       converting this error data into a human readable string.

       err_data_size  :  On  input,  err_data_size  indicates  the size of the err_data buffer in
       bytes.  On output, err_data_size will be set to the number of bytes copied to the err_data
       buffer.  The err_data information is typically used with fi_eq_strerror to provide details
       about the type of error that occurred.

       For compatibility purposes, if err_data_size is 0 on input, or the fabric was opened  with
       release  < 1.5, err_data will be set to a data buffer owned by the provider.  The contents
       of the buffer will remain valid until a subsequent read call against the EQ.  Applications
       must  serialize  access  to  the  EQ  when  processing  errors  to  ensure that the buffer
       referenced by err_data does no change.

NOTES

       If an event queue has been overrun, it will be placed  into  an  'overrun'  state.   Write
       operations  against  an  overrun  EQ  will  fail  with -FI_EOVERRUN.  Read operations will
       continue to return any valid, non-corrupted events, if available.  After all valid  events
       have been retrieved, any attempt to read the EQ will result in it returning an FI_EOVERRUN
       error event.  Overrun event queues are considered fatal and may  not  be  used  to  report
       additional events once the overrun occurs.

RETURN VALUES

       fi_eq_open  :  Returns  0  on success.  On error, a negative value corresponding to fabric
       errno is returned.

       fi_eq_read / fi_eq_readerr / fi_eq_sread : On success, returns the number  of  bytes  read
       from  the  event  queue.   On  error,  a  negative  value corresponding to fabric errno is
       returned.  If no data is available  to  be  read  from  the  event  queue,  -FI_EAGAIN  is
       returned.

       fi_eq_write  :  On  success,  returns  the number of bytes written to the event queue.  On
       error, a negative value corresponding to fabric errno is returned.

       fi_eq_strerror : Returns a character string interpretation of the provider specific  error
       returned with a completion.

       Fabric errno values are defined in rdma/fi_errno.h.

SEE ALSO

       fi_getinfo(3), fi_endpoint(3), fi_domain(3), fi_cntr(3), fi_poll(3)

AUTHORS

       OpenFabrics.