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diff --git a/sys-utils/cytune.8 b/sys-utils/cytune.8 new file mode 100644 index 0000000..fd82391 --- /dev/null +++ b/sys-utils/cytune.8 @@ -0,0 +1,194 @@ +.\" cytune.8 -- +.\" Created: Sat Mar 4 17:44:53 1995 by faith@cs.unc.edu +.\" Update: Sat Mar 4 18:22:24 1995 by faith@cs.unc.edu +.\" Update: Sun Mar 5 06:40:12 1995 by njs@scifi.emi.net +.\" Copyright 1995 Rickard E. Faith (faith@cs.unc.edu) +.\" +.\" Permission is granted to make and distribute verbatim copies of this +.\" manual provided the copyright notice and this permission notice are +.\" preserved on all copies. +.\" +.\" Permission is granted to copy and distribute modified versions of this +.\" manual under the conditions for verbatim copying, provided that the +.\" entire resulting derived work is distributed under the terms of a +.\" permission notice identical to this one +.\" +.\" Since the Linux kernel and libraries are constantly changing, this +.\" manual page may be incorrect or out-of-date. The author(s) assume no +.\" responsibility for errors or omissions, or for damages resulting from +.\" the use of the information contained herein. The author(s) may not +.\" have taken the same level of care in the production of this manual, +.\" which is licensed free of charge, as they might when working +.\" professionally. +.\" +.\" Formatted or processed versions of this manual, if unaccompanied by +.\" the source, must acknowledge the copyright and authors of this work. +.\" " +.TH CYTUNE 8 "September 2011" "util-linux" "System Administration" +.SH NAME +cytune \- tune driver parameters for Cyclades-Z multiport serial card +.SH SYNOPSIS +.B cytune +[options] tty [...] +.SH DESCRIPTION +.B cytune +queries and modifies the interruption threshold for the Cyclades driver. +Each serial line on a Cyclades card has a 12-byte FIFO for input (and another +12-byte FIFO for output). The "threshold" specifies how many input +characters must be present in the FIFO before an interruption is raised. +When a Cyclades tty is opened, this threshold is set to a default value based +on baud rate: +.sp +.RS +Baud Threshold +.sp +50-4800 10 +.br +9600 8 +.br +19200 4 +.br +38400 2 +.br +57600-150000 1 +.RE +.PP +If the threshold is set too low, the large number of interruptions can load +the machine and decrease overall system throughput. If the threshold is set +too high, the FIFO buffer can overflow, and characters will be lost. Slower +machines, however, may not be able to deal with the interrupt load, and will +require that the threshold be adjusted upwards. +.PP +If the cyclades driver was compiled with +.B ENABLE_MONITORING +defined, the cytune command can be used with the +.B \-q +option to report interrupts over the monitoring interval and characters +transferred over the monitoring interval. It will also report the state of +the FIFO. The maximum number of characters in the FIFO when an interrupt +occurred, the instantaneous count of characters in the FIFO, and how many +characters are now in the FIFO are reported. This output might look like +this: +.sp +.RS +/dev/cubC0: 830 ints, 9130 chars; fifo: 11 threshold, 11 max, 11 now +.br + 166.259866 interrupts/second, 1828.858521 characters/second +.RE +.PP +This output indicates that for this monitoring period, the interrupts were +always being handled within one character time, because +.B max +never rose above +.BR threshold . +This is good, and you can probably run this way, provided that a large number +of samples come out this way. You will lose characters if you overrun the +FIFO, as the Cyclades hardware does not seem to support the RTS RS-232 signal +line for hardware flow control from the DCE to the DTE. +.PP +In query mode +.B cytune +will produce a summary report when ended with a SIGINT or when the threshold +or timeout is changed. +.PP +There may be a responsiveness vs. throughput tradeoff. The Cyclades card, at +the higher speeds, is capable of putting a very high interrupt load on the +system. This will reduce the amount of CPU time available for other tasks on +your system. However, the time it takes to respond to a single character may +be increased if you increase the threshold. This might be noticed by +monitoring +.BR ping (8) +times on a SLIP link controlled by a Cyclades card. If your SLIP link is +generally used for interactive work such as +.BR telnet (1), +you may want to leave the threshold low, so that characters are responded to +as quickly as possible. If your SLIP link is generally used for file +transfer, WWW, and the like, setting the FIFO to a high value is likely to +reduce the load on your system while not significantly affecting throughput. +Alternatively, see the +.B \-t +or +.B \-T +options to adjust the time that the cyclades waits before flushing its +buffer. Units are 5ms. +.PP +If you are running a mouse on a Cyclades port, it is likely that you would +want to maintain the threshold and timeout at a low value. +.PP +.SH OPTIONS +.TP +\fB\-s\fR, \fB\-\-set\-threshold\fR \fIvalue\fR +Set the current threshold to +.I value +characters. Note that if the +.I tty +is not being held open by another process, the threshold will be reset on the +next open. Only values between 1 and 12, inclusive, are permitted. +.TP +\fB\-t\fR, \fB\-\-set\-flush\fR \fIvalue\fR +Set the current flush timeout to +.I value +units. Note that if the +.I tty +is not being held open by another process, the threshold will be reset on the +next open. Only values between 0 and 255, inclusive, are permitted. Setting +.I value +to zero forces the default, currently 0x20 (160ms), but soon to be 0x02 +(10ms). Units are 5 ms. +.TP +\fB\-g\fR, \fB\-\-get\-threshold\fR +Get the current threshold and timeout. +.TP +\fB\-S\fR, \fB\-\-set\-default\-threshold\fR \fIvalue\fR +Set the default threshold to +.I value +characters. When the +.I tty +is next opened, this value will be used instead of the default. Only values +between 1 and 12, inclusive, are permitted. +.TP +\fB\-T\fR, \fB\-\-set\-default\-flush\fR \fIvalue\fR +Set the default flush timeout to +.I value +units. When the +.I tty +is next opened, this value will be used instead of the default. If +.I value +is zero, then the the value will default to 0x20 (160ms), soon to be 0x02 +(10ms). +.TP +\fB\-G\fR, \fB\-\-get\-glush\fR +Get the default threshold and flush timeout values. +.TP +\fB\-q\fR, \fB\-\-stats\fR +Gather statistics about the +.IR tty . +The results are only valid if the Cyclades driver has been compiled with +.B ENABLE_MONITORING +defined. This is probably not the default. +.TP +\fB\-i\fR, \fB\-\-interval\fR \fIinterval\fR +Statistics will be gathered every +.I interval +seconds. +.SH BUGS +If you run two copies of +.B cytune +at the same time to report statistics about the same port, the 'ints', 'chars', +and 'max' value will be reset and not reported correctly. +.B cytune +should prevent this, but does not. +.\" .SH AUTHOR +.\" Nick Simicich (njs@scifi.emi.net), with modifications by +.\" Rik Faith (faith@cs.unc.edu) +.SH FILES +.I /dev/ttyC[0-8] +.br +.I /dev/cubC[0-8] +.SH "SEE ALSO" +.BR setserial (8) +.SH AVAILABILITY +The cytune command is part of the util-linux package and is available from +.UR ftp://\:ftp.kernel.org\:/pub\:/linux\:/utils\:/util-linux/ +Linux Kernel Archive +.UE . |