Trace Device не доехал до Греции

На незапланированном рассмотрении IWP9 Ron Minnich опубликовал документацию для нового драйвера трассировки ядра Plan9. К сожалению, он и его соавторы Джон Floren и Aki Nyrhinen не смогут посетить IWP9 в этом году, и поэтому решили опубликовать этот документ раньше.

Исходный код модифицированного загрузчика 8l находится в /n/sources/contrib/rminnich/tracepaper/, а сам драйвер скоро должен быть выпущен. Вы можете скачать этот документ в формате PDF в недавно открывшемся разделе 2008 в архиве документации по IPW9. Вот аннотация, для затравки:

Abstract

We describe a Plan 9 trace device, devtrace, its uses and its implemen- tations. The trace device can be used to selectively trace functions and processes in Plan 9. Users can enable a range of functions to be traced, observe which of the functions are called, in what order, what their pa- rameters are, and the time spent (in CPU ticks) in each function. We have developed a set of tools for plotting this data to make the progres- sion and timing of function calls clear. Since all Plan 9 le systems are user level processes, it is possible to trace a single process le I/O as it progresses from the process, through the le server processes, and to disk. This measurement, in turn, allows us to propose changes in the Plan 9 kernel design and implementation to improve performance.

The implementation of the trace device went through several distinct phases. In the end, we arrived at a device with a textual interface. Users need not write programs to use the trace facility. The trace device does not rewrite kernel code and hence does not require privileged access (as in Linux or Solaris). Any user of a Plan 9 terminal can measure their systems performance.

The trace device was designed to help us with performance evaluation of Plan 9 on two supercomputers, the Cray XT4 and the IBM BG/P.

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