libtracing/channels.h

   1 #ifndef _LTT_CHANNELS_H
   2 #define _LTT_CHANNELS_H
   3
   4 /*
   5  * Copyright (C) 2008 Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca)
   6  *
   7  * Dynamic tracer channel allocation.
   8  */
   9
  10 #include <linux/limits.h>
  11 #include <linux/kref.h>
  12 #include <linux/list.h>
  13
  14 #define EVENTS_PER_CHANNEL      65536
  15
  16 struct ltt_trace_struct;
  17 struct rchan_buf;
  18
  19 struct ltt_channel_struct {
  20         /* First 32 bytes cache-hot cacheline */
  21         struct ltt_trace_struct *trace;
  22         void *buf;
  23         void *trans_channel_data;
  24         int overwrite:1;
  25         int active:1;
  26         unsigned int n_subbufs_order;
  27         unsigned long commit_count_mask;        /*
  28                                                  * Commit count mask, removing
  29                                                  * the MSBs corresponding to
  30                                                  * bits used to represent the
  31                                                  * subbuffer index.
  32                                                  */
  33         /* End of first 32 bytes cacheline */
  34
  35         /*
  36          * buffer_begin - called on buffer-switch to a new sub-buffer
  37          * @buf: the channel buffer containing the new sub-buffer
  38          */
  39         void (*buffer_begin) (struct rchan_buf *buf,
  40                         u64 tsc, unsigned int subbuf_idx);
  41         /*
  42          * buffer_end - called on buffer-switch to a new sub-buffer
  43          * @buf: the channel buffer containing the previous sub-buffer
  44          */
  45         void (*buffer_end) (struct rchan_buf *buf,
  46                         u64 tsc, unsigned int offset, unsigned int subbuf_idx);
  47         struct kref kref;       /* Channel transport reference count */
  48         unsigned int subbuf_size;
  49         unsigned int subbuf_cnt;
  50         const char *channel_name;
  51 } ____cacheline_aligned;
  52
  53 struct ltt_channel_setting {
  54         unsigned int subbuf_size;
  55         unsigned int subbuf_cnt;
  56         struct kref kref;       /* Number of references to structure content */
  57         struct list_head list;
  58         unsigned int index;     /* index of channel in trace channel array */
  59         u16 free_event_id;      /* Next event ID to allocate */
  60         char name[PATH_MAX];
  61 };
  62
  63 int ltt_channels_register(const char *name);
  64 int ltt_channels_unregister(const char *name);
  65 int ltt_channels_set_default(const char *name,
  66                              unsigned int subbuf_size,
  67                              unsigned int subbuf_cnt);
  68 const char *ltt_channels_get_name_from_index(unsigned int index);
  69 int ltt_channels_get_index_from_name(const char *name);
  70 struct ltt_channel_struct *ltt_channels_trace_alloc(unsigned int *nr_channels,
  71                                                     int overwrite,
  72                                                     int active);
  73 void ltt_channels_trace_free(struct ltt_channel_struct *channels);
  74 int _ltt_channels_get_event_id(const char *channel, const char *name);
  75 int ltt_channels_get_event_id(const char *channel, const char *name);
  76
  77 #endif /* _LTT_CHANNELS_H */