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diff --git a/system_cmds/latency.tproj/latency.1 b/system_cmds/latency.tproj/latency.1 new file mode 100644 index 0000000..4e0eb3e --- /dev/null +++ b/system_cmds/latency.tproj/latency.1 @@ -0,0 +1,106 @@ +.\" Copyright (c) 2000, Apple Computer, Inc. All rights reserved. +.\" +.Dd March 28, 2000 +.Dt LATENCY 1 +.Os "Mac OS X" +.Sh NAME +.Nm latency +.Nd monitors scheduling and interrupt latency +.Sh SYNOPSIS +.Nm latency +.Op Fl p Ar priority +.Op Fl h +.Op Fl m +.Op Fl st Ar threshold +.Op Fl it Ar threshold +.Op Fl c Ar code_file +.Op Fl l Ar log_file +.Op Fl R Ar raw_file +.Op Fl n Ar kernel +.Sh DESCRIPTION +The +.Nm latency +utility provides scheduling and interrupt-latency statistics. +Due to the kernel tracing facility it uses to operate, +the command requires root privileges. +.Pp +The arguments are as follows: +.Bl -tag -width Ds +.\" ========== +.It Fl c Ar code_file +When the +.Fl c +option is specified, it takes a path to a code file +that contains the mappings for the system calls. +This option overrides the default location of the system call code file, +which is found in /usr/share/misc/trace.codes. +.\" ========== +.It Fl h +Display high resolution interrupt latencies and write them to latencies.csv (truncate existing file) upon exit. +.\" ========== +.It Fl m +Display per-CPU interrupt latency statistics. +.\" ========== +.It Fl it Ar threshold +Set the interrupt latency threshold, +expressed in microseconds. +If the latency exceeds this value, +and a log file has been specified, +a record of what occurred during this time is recorded. +.\" ========== +.It Fl l Ar log_file +Specifies a log file that is written to when +either the interrupt or scheduling latency is exceeded. +.\" ========== +.It Fl n Ar kernel +By default, +.Nm latency +acts on the default /System/Library/Kernels/kernel.development. +This option allows you to specify an alternate booted kernel. +.\" ========== +.It Fl p Ar priority +Specifies the priority level to observe scheduler latencies for. +The default is realtime ( +.Ar 97 +). A range of priorities to monitor +can also be provided, for example +.Ar 31-47 +or +.Ar 0-127 +. +.\" ========== +.It Fl st Ar threshold +Set the scheduler latency threshold in microseconds. +If latency exceeds this, and a log file has been specified, +a record of what occurred during this time is recorded. +.\" ========== +.It Fl R Ar raw_file +Specifies a raw trace file to use as input. +.El +.Pp +The data columns displayed are as follows: +.Bl -tag -width LAST_PATHNAME_WAITED_FOR +.It SCHEDULER +The number of context switches that fall within the described delay. +.It INTERRUPTS +The number of interrupts that fall within the described delay. +.El +.Pp +The +.Nm latency +utility is also SIGWINCH savvy, so adjusting your window geometry will change +the list of delay values displayed. +.Sh SAMPLE USAGE +.Pp +latency -p 97 -st 20000 -it 1000 -l /var/tmp/latency.log +.Pp +The +.Nm latency +utility will watch threads with priority 97 for scheduling latencies. +The threshold for the scheduler is set to 20000 microseconds. +The threshold for interrupts is set to 1000 microseconds. +Latencies that exceed these thresholds will be logged in /var/tmp/latency.log. +.Sh SEE ALSO +.Xr fs_usage 1 , +.Xr sc_usage 1 , +.Xr top 1 |