| 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748 |
- .TH UART 3
- .SH NAME
- ptrace \- process scheduling traces
- .SH SYNOPSIS
- .nf
- .B bind -a #σ /dev
- .B /dev/ptrace
- .B /dev/ptracectl
- .fi
- .SH DESCRIPTION
- .PP
- The process trace device is a replacement for the trace facility in
- .IR proc (3)
- to report more information about process events.
- .PP
- The
- .B ptracectl
- admits the following requests:
- .TP
- .BI size " n
- Set the size of the buffer to
- .I n
- entries. Before issuing this request tracing is not enabled.
- .TP
- .BI trace " pid value"
- Set the trace on or off for the process with the given pid.
- .PP
- The
- .B ptrace
- file reports an integral number of events when read. To avoid
- too much interference with scheduling, it does not block readers.
- When no more events are available the read returns an EOF indication,
- but the program is expected to poll the device for further events.
- This behavior mimics what
- .IR proc (3)
- does with the trace interface.
- .SH SOURCE
- .B /sys/src/9/port/devptrace.c
- .br
- .B /sys/src/9k/port/devptrace.c
- .SH "SEE ALSO
- .IR ptrace (1),
- .IR ptrace (2).
- .SH BUGS
- If the buffer size is too small, events will be discarded.
- .PP
- The reader must poll the trace device.
|
