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diff --git a/lib/libdevstat/devstat.3 b/lib/libdevstat/devstat.3 new file mode 100644 index 0000000..fb82146 --- /dev/null +++ b/lib/libdevstat/devstat.3 @@ -0,0 +1,795 @@ +.\" +.\" Copyright (c) 1998, 1999, 2001 Kenneth D. Merry. +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. The name of the author may not be used to endorse or promote products +.\" derived from this software without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" $FreeBSD$ +.\" +.Dd March 18, 2003 +.Dt DEVSTAT 3 +.Os +.Sh NAME +.Nm devstat , +.Nm devstat_getnumdevs , +.Nm devstat_getgeneration , +.Nm devstat_getversion , +.Nm devstat_checkversion , +.Nm devstat_getdevs , +.Nm devstat_selectdevs , +.Nm devstat_buildmatch , +.Nm devstat_compute_statistics , +.Nm devstat_compute_etime +.Nd device statistics utility library +.Sh LIBRARY +.Lb libdevstat +.Sh SYNOPSIS +.In devstat.h +.Ft int +.Fn devstat_getnumdevs "kvm_t *kd" +.Ft long +.Fn devstat_getgeneration "kvm_t *kd" +.Ft int +.Fn devstat_getversion "kvm_t *kd" +.Ft int +.Fn devstat_checkversion "kvm_t *kd" +.Ft int +.Fn devstat_getdevs "kvm_t *kd" "struct statinfo *stats" +.Ft int +.Fo devstat_selectdevs +.Fa "struct device_selection **dev_select" +.Fa "int *num_selected" +.Fa "int *num_selections" +.Fa "long *select_generation" +.Fa "long current_generation" +.Fa "struct devstat *devices" +.Fa "int numdevs" +.Fa "struct devstat_match *matches" +.Fa "int num_matches" +.Fa "char **dev_selections" +.Fa "int num_dev_selections" +.Fa "devstat_select_mode select_mode" +.Fa "int maxshowdevs" +.Fa "int perf_select" +.Fc +.Ft int +.Fo devstat_buildmatch +.Fa "char *match_str" +.Fa "struct devstat_match **matches" +.Fa "int *num_matches" +.Fc +.Ft int +.Fo devstat_compute_statistics +.Fa "struct devstat *current" +.Fa "struct devstat *previous" +.Fa "long double etime" +.Fa "..." +.Fc +.Ft "long double" +.Fo devstat_compute_etime +.Fa "struct bintime *cur_time" +.Fa "struct bintime *prev_time" +.Fc +.Sh DESCRIPTION +The +.Nm +library is a library of helper functions for dealing with the kernel +.Xr devstat 9 +interface, which is accessible to users via +.Xr sysctl 3 +and +.Xr kvm 3 . +All functions that take a +.Vt "kvm_t *" +as first argument can be passed +.Dv NULL +instead of a kvm handle as this argument, +which causes the data to be read via +.Xr sysctl 3 . +Otherwise, it is read via +.Xr kvm 3 +using the supplied handle. +The +.Fn devstat_checkversion +function +should be called with each kvm handle that is going to be used (or with +.Dv NULL +if +.Xr sysctl 3 +is going to be used). +.Pp +The +.Fn devstat_getnumdevs +function +returns the number of devices registered with the +.Nm +subsystem in the kernel. +.Pp +The +.Fn devstat_getgeneration +function +returns the current generation of the +.Nm +list of devices in the kernel. +.Pp +The +.Fn devstat_getversion +function +returns the current kernel +.Nm +version. +.Pp +The +.Fn devstat_checkversion +function +checks the userland +.Nm +version against the kernel +.Nm +version. +If the two are identical, it returns zero. +Otherwise, it prints an appropriate error in +.Va devstat_errbuf +and returns \-1. +.Pp +The +.Fn devstat_getdevs +function +fetches the current list of devices and statistics into the supplied +.Vt statinfo +structure. +The +.Vt statinfo +structure can be found in +.In devstat.h : +.Bd -literal -offset indent +struct statinfo { + long cp_time[CPUSTATES]; + long tk_nin; + long tk_nout; + struct devinfo *dinfo; + long double snap_time; +}; +.Ed +.Pp +The +.Fn devstat_getdevs +function +expects the +.Vt statinfo +structure to be allocated, and it also expects the +.Va dinfo +subelement to be allocated and zeroed prior to the first invocation of +.Fn devstat_getdevs . +The +.Va dinfo +subelement is used to store state between calls, and should not be modified +after the first call to +.Fn devstat_getdevs . +The +.Va dinfo +subelement contains the following elements: +.Bd -literal -offset indent +struct devinfo { + struct devstat *devices; + u_int8_t *mem_ptr; + long generation; + int numdevs; +}; +.Ed +.Pp +The +.Va kern.devstat.all +.Xr sysctl 8 +variable contains an array of +.Nm +structures, but at the head of the array is the current +.Nm +generation. +The reason the generation is at the head of the buffer is so that userland +software accessing the +.Nm +statistics information can atomically get +both the statistics information and the corresponding generation number. +If client software were forced to get the generation number via a separate +.Xr sysctl 8 +variable (which is available for convenience), the list of devices could +change between the time the client gets the generation and the time the +client gets the device list. +.Pp +The +.Va mem_ptr +subelement of the +.Vt devinfo +structure is a pointer to memory that is allocated, and resized if +necessary, by +.Fn devstat_getdevs . +The devices subelement of the +.Vt devinfo +structure is basically a pointer to the beginning of the array of devstat +structures from the +.Va kern.devstat.all +.Xr sysctl 8 +variable (or the corresponding values read via +.Xr kvm 3 ) . +The generation subelement of the +.Vt devinfo +structure contains the corresponding generation number. +The +.Va numdevs +subelement of the +.Vt devinfo +structure contains the current +number of devices registered with the kernel +.Nm +subsystem. +.Pp +The +.Fn devstat_selectdevs +function +selects devices to display based upon a number of criteria: +.Bl -tag -width indent +.It specified devices +Specified devices are the first selection priority. +These are generally devices specified by name by the user e.g.\& +.Li da0 , da1 , cd0 . +.It match patterns +These are pattern matching expressions generated by +.Fn devstat_buildmatch +from user input. +.It performance +If performance mode is enabled, devices will be sorted based on the +.Va bytes +field in the +.Vt device_selection +structure passed in to +.Fn devstat_selectdevs . +The +.Va bytes +value currently must be maintained by the user. +In the future, this may be done for him in a +.Nm +library routine. +If no devices have been selected by name or by pattern, the performance +tracking code will select every device in the system, and sort them by +performance. +If devices have been selected by name or pattern, the performance tracking +code will honor those selections and will only sort among the selected +devices. +.It order in the devstat list +If the selection mode is set to +.Dv DS_SELECT_ADD , +and if there are still less +than +.Fa maxshowdevs +devices selected, +.Fn devstat_selectdevs +will automatically select up to +.Fa maxshowdevs +devices. +.El +.Pp +The +.Fn devstat_selectdevs +function +performs selections in four different modes: +.Bl -tag -width ".Dv DS_SELECT_ADDONLY" +.It Dv DS_SELECT_ADD +In +.Dq add +mode, +.Fn devstat_selectdevs +will select any unselected devices specified by name or matching pattern. +It will also select more devices, in devstat list order, until the number +of selected devices is equal to +.Fa maxshowdevs +or until all devices are +selected. +.It Dv DS_SELECT_ONLY +In +.Dq only +mode, +.Fn devstat_selectdevs +will clear all current selections, and will only select devices specified +by name or by matching pattern. +.It Dv DS_SELECT_REMOVE +In +.Dq remove +mode, +.Fn devstat_selectdevs +will remove devices specified by name or by matching pattern. +It will not select any additional devices. +.It Dv DS_SELECT_ADDONLY +In +.Dq "add only" +mode, +.Fn devstat_selectdevs +will select any unselected devices specified by name or matching pattern. +In this respect it is identical to +.Dq add +mode. +It will not, however, select any devices other than those specified. +.El +.Pp +In all selection modes, +.Fn devstat_selectdevs +will not select any more than +.Fa maxshowdevs +devices. +One exception to this is when you are in +.Dq top +mode and no devices have been selected. +In this case, +.Fn devstat_selectdevs +will select every device in the system. +Client programs must pay attention to selection order when deciding whether +to pay attention to a particular device. +This may be the wrong behavior, and probably requires additional thought. +.Pp +The +.Fn devstat_selectdevs +function +handles allocation and resizing of the +.Fa dev_select +structure passed in +by the client. +The +.Fn devstat_selectdevs +function +uses the +.Fa numdevs +and +.Fa current_generation +fields to track the +current +.Nm +generation and number of devices. +If +.Fa num_selections +is not the same +as +.Fa numdevs +or if +.Fa select_generation +is not the same as +.Fa current_generation , +.Fn devstat_selectdevs +will resize the selection list as necessary, and re-initialize the +selection array. +.Pp +The +.Fn devstat_buildmatch +function +takes a comma separated match string and compiles it into a +.Vt devstat_match +structure that is understood by +.Fn devstat_selectdevs . +Match strings have the following format: +.Pp +.D1 Ar device , Ns Ar type , Ns Ar if +.Pp +The +.Fn devstat_buildmatch +function +takes care of allocating and reallocating the match list as necessary. +Currently known match types include: +.Bl -tag -width indent +.It device type: +.Bl -tag -width ".Li enclosure" -compact +.It Li da +Direct Access devices +.It Li sa +Sequential Access devices +.It Li printer +Printers +.It Li proc +Processor devices +.It Li worm +Write Once Read Multiple devices +.It Li cd +CD devices +.It Li scanner +Scanner devices +.It Li optical +Optical Memory devices +.It Li changer +Medium Changer devices +.It Li comm +Communication devices +.It Li array +Storage Array devices +.It Li enclosure +Enclosure Services devices +.It Li floppy +Floppy devices +.El +.It interface: +.Bl -tag -width ".Li enclosure" -compact +.It Li IDE +Integrated Drive Electronics devices +.It Li SCSI +Small Computer System Interface devices +.It Li other +Any other device interface +.El +.It passthrough: +.Bl -tag -width ".Li enclosure" -compact +.It Li pass +Passthrough devices +.El +.El +.Pp +The +.Fn devstat_compute_statistics +function provides complete statistics calculation. +There are four arguments for which values +.Em must +be supplied: +.Fa current , +.Fa previous , +.Fa etime , +and the terminating argument for the varargs list, +.Dv DSM_NONE . +For most applications, the user will want to supply valid +.Vt devstat +structures for both +.Fa current +and +.Fa previous . +In some instances, for instance when calculating statistics since system +boot, the user may pass in a +.Dv NULL +pointer for the +.Fa previous +argument. +In that case, +.Fn devstat_compute_statistics +will use the total stats in the +.Fa current +structure to calculate statistics over +.Fa etime . +For each statistics to be calculated, the user should supply the proper +enumerated type (listed below), and a variable of the indicated type. +All statistics are either integer values, for which a +.Vt u_int64_t +is used, +or floating point, for which a +.Vt "long double" +is used. +The statistics that may be calculated are: +.Bl -tag -width ".Dv DSM_TRANSFERS_PER_SECOND_OTHER" +.It Dv DSM_NONE +type: N/A +.Pp +This +.Em must +be the last argument passed to +.Fn devstat_compute_statistics . +It is an argument list terminator. +.It Dv DSM_TOTAL_BYTES +type: +.Vt "u_int64_t *" +.Pp +The total number of bytes transferred between the acquisition of +.Fa previous +and +.Fa current . +.It Dv DSM_TOTAL_BYTES_READ +.It Dv DSM_TOTAL_BYTES_WRITE +.It Dv DSM_TOTAL_BYTES_FREE +type: +.Vt "u_int64_t *" +.Pp +The total number of bytes in transactions of the specified type +between the acquisition of +.Fa previous +and +.Fa current . +.It Dv DSM_TOTAL_TRANSFERS +type: +.Vt "u_int64_t *" +.Pp +The total number of transfers between the acquisition of +.Fa previous +and +.Fa current . +.It Dv DSM_TOTAL_TRANSFERS_OTHER +.It Dv DSM_TOTAL_TRANSFERS_READ +.It Dv DSM_TOTAL_TRANSFERS_WRITE +.It Dv DSM_TOTAL_TRANSFERS_FREE +type: +.Vt "u_int64_t *" +.Pp +The total number of transactions of the specified type between +the acquisition of +.Fa previous +and +.Fa current . +.It Dv DSM_TOTAL_BLOCKS +type: +.Vt "u_int64_t *" +.Pp +The total number of blocks transferred between the acquisition of +.Fa previous +and +.Fa current . +This number is in terms of the blocksize reported by the device. +If no blocksize has been reported (i.e., the block size is 0), a default +blocksize of 512 bytes will be used in the calculation. +.It Dv DSM_TOTAL_BLOCKS_READ +.It Dv DSM_TOTAL_BLOCKS_WRITE +.It Dv DSM_TOTAL_BLOCKS_FREE +type: +.Vt "u_int64_t *" +.Pp +The total number of blocks of the specified type between the acquisition of +.Fa previous +and +.Fa current . +This number is in terms of the blocksize reported by the device. +If no blocksize has been reported (i.e., the block size is 0), a default +blocksize of 512 bytes will be used in the calculation. +.It Dv DSM_KB_PER_TRANSFER +type: +.Vt "long double *" +.Pp +The average number of kilobytes per transfer between the acquisition of +.Fa previous +and +.Fa current . +.It Dv DSM_KB_PER_TRANSFER_READ +.It Dv DSM_KB_PER_TRANSFER_WRITE +.It Dv DSM_KB_PER_TRANSFER_FREE +type: +.Vt "long double *" +.Pp +The average number of kilobytes in the specified type transaction between +the acquisition of +.Fa previous +and +.Fa current . +.It Dv DSM_TRANSFERS_PER_SECOND +type: +.Vt "long double *" +.Pp +The average number of transfers per second between the acquisition of +.Fa previous +and +.Fa current . +.It Dv DSM_TRANSFERS_PER_SECOND_OTHER +.It Dv DSM_TRANSFERS_PER_SECOND_READ +.It Dv DSM_TRANSFERS_PER_SECOND_WRITE +.It Dv DSM_TRANSFERS_PER_SECOND_FREE +type: +.Vt "long double *" +.Pp +The average number of transactions of the specified type per second +between the acquisition of +.Fa previous +and +.Fa current . +.It Dv DSM_MB_PER_SECOND +type: +.Vt "long double *" +.Pp +The average number of megabytes transferred per second between the +acquisition of +.Fa previous +and +.Fa current . +.It Dv DSM_MB_PER_SECOND_READ +.It Dv DSM_MB_PER_SECOND_WRITE +.It Dv DSM_MB_PER_SECOND_FREE +type: +.Vt "long double *" +.Pp +The average number of megabytes per second in the specified type of +transaction between the acquisition of +.Fa previous +and +.Fa current . +.It Dv DSM_BLOCKS_PER_SECOND +type: +.Vt "long double *" +.Pp +The average number of blocks transferred per second between the acquisition of +.Fa previous +and +.Fa current . +This number is in terms of the blocksize reported by the device. +If no blocksize has been reported (i.e., the block size is 0), a default +blocksize of 512 bytes will be used in the calculation. +.It Dv DSM_BLOCKS_PER_SECOND_READ +.It Dv DSM_BLOCKS_PER_SECOND_WRITE +.It Dv DSM_BLOCKS_PER_SECOND_FREE +type: +.Vt "long double *" +.Pp +The average number of blocks per second in the specified type of transaction +between the acquisition of +.Fa previous +and +.Fa current . +This number is in terms of the blocksize reported by the device. +If no blocksize has been reported (i.e., the block size is 0), a default +blocksize of 512 bytes will be used in the calculation. +.It Dv DSM_MS_PER_TRANSACTION +type: +.Vt "long double *" +.Pp +The average duration of transactions between the acquisition of +.Fa previous +and +.Fa current . +.It Dv DSM_MS_PER_TRANSACTION_OTHER +.It Dv DSM_MS_PER_TRANSACTION_READ +.It Dv DSM_MS_PER_TRANSACTION_WRITE +.It Dv DSM_MS_PER_TRANSACTION_FREE +type: +.Vt "long double *" +.Pp +The average duration of transactions of the specified type between the +acquisition of +.Fa previous +and +.Fa current . +.It Dv DSM_BUSY_PCT +type: +.Vt "long double *" +.Pp +The percentage of time the device had one or more transactions outstanding +between the acquisition of +.Fa previous +and +.Fa current . +.It Dv DSM_QUEUE_LENGTH +type: +.Vt "u_int64_t *" +.Pp +The number of not yet completed transactions at the time when +.Fa current +was acquired. +.It Dv DSM_SKIP +type: N/A +.Pp +If you do not need a result from +.Fn devstat_compute_statistics , +just put +.Dv DSM_SKIP +as first (type) parameter and +.Dv NULL +as second parameter. +This can be useful in scenarios where the statistics to be calculated +are determined at run time. +.El +.Pp +The +.Fn devstat_compute_etime +function +provides an easy way to find the difference in seconds between two +.Vt bintime +structures. +This is most commonly used in conjunction with the time recorded by the +.Fn devstat_getdevs +function (in +.Vt "struct statinfo" ) +each time it fetches the current +.Nm +list. +.Sh RETURN VALUES +The +.Fn devstat_getnumdevs , +.Fn devstat_getgeneration , +and +.Fn devstat_getversion +function +return the indicated sysctl variable, or \-1 if there is an error +fetching the variable. +.Pp +The +.Fn devstat_checkversion +function +returns 0 if the kernel and userland +.Nm +versions match. +If they do not match, it returns \-1. +.Pp +The +.Fn devstat_getdevs +and +.Fn devstat_selectdevs +functions +return \-1 in case of an error, 0 if there is no error, and 1 if the device +list or selected devices have changed. +A return value of 1 from +.Fn devstat_getdevs +is usually a hint to re-run +.Fn devstat_selectdevs +because the device list has changed. +.Pp +The +.Fn devstat_buildmatch +function returns \-1 for error, and 0 if there is no error. +.Pp +The +.Fn devstat_compute_etime +function +returns the computed elapsed time. +.Pp +The +.Fn devstat_compute_statistics +function returns \-1 for error, and 0 for success. +.Pp +If an error is returned from one of the +.Nm +library functions, the reason for the error is generally printed in +the global string +.Va devstat_errbuf +which is +.Dv DEVSTAT_ERRBUF_SIZE +characters long. +.Sh SEE ALSO +.Xr systat 1 , +.Xr kvm 3 , +.Xr sysctl 3 , +.Xr iostat 8 , +.Xr rpc.rstatd 8 , +.Xr sysctl 8 , +.Xr vmstat 8 , +.Xr devstat 9 +.Sh HISTORY +The +.Nm +statistics system first appeared in +.Fx 3.0 . +The new interface (the functions prefixed with +.Li devstat_ ) +first appeared in +.Fx 5.0 . +.Sh AUTHORS +.An Kenneth Merry Aq ken@FreeBSD.org +.Sh BUGS +There should probably be an interface to de-allocate memory allocated by +.Fn devstat_getdevs , +.Fn devstat_selectdevs , +and +.Fn devstat_buildmatch . +.Pp +The +.Fn devstat_selectdevs +function +should probably not select more than +.Fa maxshowdevs +devices in +.Dq top +mode when no devices have been selected previously. +.Pp +There should probably be functions to perform the statistics buffer +swapping that goes on in most of the clients of this library. +.Pp +The +.Vt statinfo +and +.Vt devinfo +structures should probably be cleaned up and thought out a little more. |
