[SPAM] Re: Self-contained one purpose objects

Chris Johns chrisj at rtems.org
Thu Jul 23 10:29:26 UTC 2015

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Content preview:  On 23/07/2015 7:16 pm, Sebastian Huber wrote: > The Classic
   RTEMS and POSIX APIs have at least three weaknesses. > > * Dynamic memory
   (the workspace) is used to allocate object pools. This > requires a complex
   configuration with heavy use of the C pre-processor. > > * Objects are created
   via function calls which return an object identifier. > The object operations
   use this identifier and internally map it to an > internal object representation.
   > > * The object operations use a rich set of options and attributes. Each
   time > these parameters must be evaluated and validated to figure out what
   to > do. > > For applications that use fine grained locking the overhead
  to map the > identifier to the object representation and the parameter evaluation
   is a > significant overhead the may degrade the performance dramatically.
   An > example > is the FreeBSD network stack which hundreds of locks in a
  basic setup. > Here > the performance can be easily measured in terms of throughput
   and processor > utilization. The port of the FreeBSD network stack uses now
   its own > priority > inheritance mutex implementation which is not based
  on the classic RTEMS > objects. The blocking part however uses the standard
   thread queues. The > overall implementation is quite simple. > > Another
  example which benefits from self-contained objects is OpenMP. For > OpenMP
   the performance of the POSIX configuration of libgomp and an > optimized
  > implementation using self-contained objects available via Newlib > <sys/lock.h>
   > is significantly different, see https://devel.rtems.org/ticket/2274. >
  Some test > cases are more than a hundred times slower in the POSIX configuration
   of > libgomp. > > Since the Newlib should use locks to protect some global
   data structures > (https://devel.rtems.org/ticket/1247) and the GCC uses
  locks for the C++ > and > OpenMP support the application must take this into
   account. It is > difficult to > figure out how many and which objects will
   be used by Newlib and GCC for a > particular application. It would be much

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Subject: Re: Self-contained one purpose objects
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