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gdb: Caching Target Data

 
 10.21 Caching Data of Targets
 =============================
 
 GDB caches data exchanged between the debugger and a target.  Each cache
 is associated with the address space of the inferior.  Inferiors
 and Programs, about inferior and address space.  Such caching
 generally improves performance in remote debugging (Remote
 Debugging), because it reduces the overhead of the remote protocol by
 bundling memory reads and writes into large chunks.  Unfortunately,
 simply caching everything would lead to incorrect results, since GDB
 does not necessarily know anything about volatile values, memory-mapped
 I/O addresses, etc.  Furthermore, in non-stop mode (Non-Stop
 Mode) memory can be changed _while_ a gdb command is executing.
 Therefore, by default, GDB only caches data known to be on the stack(1)
 or in the code segment.  Other regions of memory can be explicitly
 marked as cacheable; Memory Region Attributes.
 
 'set remotecache on'
 'set remotecache off'
      This option no longer does anything; it exists for compatibility
      with old scripts.
 
 'show remotecache'
      Show the current state of the obsolete remotecache flag.
 
 'set stack-cache on'
 'set stack-cache off'
      Enable or disable caching of stack accesses.  When 'on', use
      caching.  By default, this option is 'on'.
 
 'show stack-cache'
      Show the current state of data caching for memory accesses.
 
 'set code-cache on'
 'set code-cache off'
      Enable or disable caching of code segment accesses.  When 'on', use
      caching.  By default, this option is 'on'.  This improves
      performance of disassembly in remote debugging.
 
 'show code-cache'
      Show the current state of target memory cache for code segment
      accesses.
 
 'info dcache [line]'
      Print the information about the performance of data cache of the
      current inferior's address space.  The information displayed
      includes the dcache width and depth, and for each cache line, its
      number, address, and how many times it was referenced.  This
      command is useful for debugging the data cache operation.
 
      If a line number is specified, the contents of that line will be
      printed in hex.
 
 'set dcache size SIZE'
      Set maximum number of entries in dcache (dcache depth above).
 
 'set dcache line-size LINE-SIZE'
      Set number of bytes each dcache entry caches (dcache width above).
      Must be a power of 2.
 
 'show dcache size'
      Show maximum number of dcache entries.  info dcache Caching
      Target Data.
 
 'show dcache line-size'
      Show default size of dcache lines.
 
    ---------- Footnotes ----------
 
    (1) In non-stop mode, it is moderately rare for a running thread to
 modify the stack of a stopped thread in a way that would interfere with
 a backtrace, and caching of stack reads provides a significant speed up
 of remote backtraces.
 

Info Catalog gdb: Character Sets gdb: Data gdb: Searching Memory