libust/tracerconst.h

   1 /*
   2  * Copyright (C) 2009 - Pierre-Marc Fournier (pierre-marc dot fournier at polymtl dot ca)
   3  * Copyright (C) 2008 - Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca)
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2.1 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  18  */
  19
  20 #ifndef TRACERCONST_H
  21 #define TRACERCONST_H
  22
  23 /* Hardcoded event headers
  24  *
  25  * event header for a trace with active heartbeat : 27 bits timestamps
  26  *
  27  * headers are 32-bits aligned. In order to insure such alignment, a dynamic per
  28  * trace alignment value must be done.
  29  *
  30  * Remember that the C compiler does align each member on the boundary
  31  * equivalent to their own size.
  32  *
  33  * As relay subbuffers are aligned on pages, we are sure that they are 4 and 8
  34  * bytes aligned, so the buffer header and trace header are aligned.
  35  *
  36  * Event headers are aligned depending on the trace alignment option.
  37  *
  38  * Note using C structure bitfields for cross-endianness and portability
  39  * concerns.
  40  */
  41
  42 #define LTT_RESERVED_EVENTS     3
  43 #define LTT_EVENT_BITS          5
  44 #define LTT_FREE_EVENTS         ((1 << LTT_EVENT_BITS) - LTT_RESERVED_EVENTS)
  45 #define LTT_TSC_BITS            27
  46 #define LTT_TSC_MASK            ((1 << LTT_TSC_BITS) - 1)
  47
  48 struct ltt_event_header {
  49         u32 id_time;            /* 5 bits event id (MSB); 27 bits time (LSB) */
  50 };
  51
  52 /* Reservation flags */
  53 #define LTT_RFLAG_ID                    (1 << 0)
  54 #define LTT_RFLAG_ID_SIZE               (1 << 1)
  55 #define LTT_RFLAG_ID_SIZE_TSC           (1 << 2)
  56
  57 #define LTT_MAX_SMALL_SIZE              0xFFFFU
  58
  59 #endif /* TRACERCONST_H */