Monitoring System Activities (sar)
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Organize and view data about system activity
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Access system activity data on a special request basis
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Generate automatic reports to measure and monitor system performance, and special request reports to pinpoint specific performance problems. "Collecting System Activity Data Automatically (sar)" describes these tools.
For a detailed description of this command, refer to sar(1).
How to Check File Access (sar -a)
Display file access operation statistics with the sar -a command.
$ sar -a SunOS venus 5.8 Generic sun4u 09/07/99 00:00:00 iget/s namei/s dirbk/s 01:00:00 0 0 0 02:00:02 0 0 0 03:00:00 0 1 0 04:00:00 0 0 0 05:00:01 0 0 0 06:00:00 0 0 0 Average 0 1 0 |
The operating system routines reported are described in the following table.
Table 36-7 Output from the sar -a Command|
Field Name |
Description |
|---|---|
|
iget/s |
The number of requests made for inodes that were not in the directory name lookup cache (dnlc). |
|
namei/s |
This is the number of file system path searches per second. If namei does not find a directory name in the dnlc, it calls iget to get the inode for either a file or directory. Hence, most igets are the result of dnlc misses. |
|
dirbk/s |
This is the number of directory block reads issued per second. |
The larger the values reported, the more time the kernel is spending to access user files. The amount of time reflects how heavily programs and applications are using the file systems. The -a option is helpful for viewing how disk-dependent an application is.
How to Check Buffer Activity (sar -b)
Display buffer activity statistics with the sar -b command.
The buffer is used to cache metadata, which includes inodes, cylinder group blocks, and indirect blocks.
$ sar -b 00:00:00 bread/s lread/s %rcache bwrit/s lwrit/s %wcache pread/s pwrit/s 01:00:00 0 0 100 0 0 55 0 0 |
The buffer activities displayed by the -b option are described in the table below. The most important entries are the cache hit ratios %rcache and %wcache, which measure the effectiveness of system buffering. If %rcache falls below 90, or if %wcache falls below 65, it may be possible to improve performance by increasing the buffer space.
Table 36-8 Output from the sar -b Command|
Field Name |
Description |
|---|---|
|
bread/s |
Average number of reads per second submitted to the buffer cache from the disk |
|
lread/s |
Average number of logical reads per second from the buffer cache |
|
%rcache |
Fraction of logical reads found in the buffer cache (100% minus the ratio of bread/s to lread/s) |
|
bwrit/s |
Average number of physical blocks (512 blocks) written from the buffer cache to disk, per second |
|
lwrite/s |
Average number of logical writes to the buffer cache, per second |
|
%wcache |
Fraction of logical writes found in the buffer cache(100% minus the ratio of bwrit/s to lwrit/s) |
|
pread/s |
Average number of physical reads, per second, using character device interfaces |
|
pwrit/s |
Average number of physical write requests, per second, using character device interfaces |
Example--Checking Buffer Activity
The following abbreviated example of sar -b output shows that the %rcache and %wcache buffers are not causing any slowdowns, because all the data is within acceptable limits.
$ sar -b SunOS venus 5.8 Generic sun4u 09/07/99 00:00:00 bread/s lread/s %rcache bwrit/s lwrit/s %wcache pread/s pwrit/s 01:00:00 0 0 100 0 0 55 0 0 02:00:02 0 0 100 0 0 55 0 0 03:00:00 0 0 100 0 0 72 0 0 04:00:00 0 0 100 0 0 56 0 0 05:00:01 0 0 100 0 0 55 0 0 06:00:00 0 0 100 0 0 55 0 0 Average 0 0 94 0 0 64 0 0 |
How to Check System Call Statistics (sar -c)
Display system call statistics by using the sar -c command.
$ sar -c 00:00:00 scall/s sread/s swrit/s fork/s exec/s rchar/s wchar/s 01:00:00 38 2 2 0.00 0.00 149 120 |
The table below describes the following system call categories reported by the -c option. Typically, reads and writes account for about half of the total system calls, although the percentage varies greatly with the activities that are being performed by the system.
Table 36-9 Output from the sar -c Command|
Field Name |
Description |
|---|---|
|
scall/s |
All types of system calls per second (generally about 30 per second on a busy four- to six-user system) |
|
sread/s |
read system calls per second |
|
swrit/s |
write system calls per second |
|
fork/s |
fork system calls per second (about 0.5 per second on a four- to six-user system); this number will increase if shell scripts are running |
|
exec/d |
exec system calls per second; if exec/s divided by fork/s is greater than three, look for inefficient PATH variables |
|
rchar/s |
Characters (bytes) transferred by read system calls per second |
|
wchar/s |
Characters (bytes) transferred by write system calls per second |
Example--Checking System Call Statistics
The following abbreviated example shows output from the sar -c command.
$ sar -c SunOS venus 5.8 Generic sun4u 09/07/99 00:00:00 scall/s sread/s swrit/s fork/s exec/s rchar/s wchar/s 01:00:00 38 2 2 0.00 0.00 149 120 02:00:02 38 2 2 0.00 0.00 149 120 03:00:00 42 2 2 0.05 0.05 218 147 04:00:00 39 2 2 0.01 0.00 155 123 05:00:01 38 2 2 0.00 0.00 150 120 06:00:00 38 2 2 0.01 0.00 149 120 Average 50 4 3 0.02 0.02 532 238 |
How to Check Disk Activity (sar -d)
Display disk activity statistics with the sar -d command.
$ sar -d 00:00:00 device %busy avque r+w/s blks/s avwait avserv 01:00:00 fd0 0 0.0 0 0 0.0 0.0 |
The table below describes the disk devices activities reported by the -d option. Note that queue lengths and wait times are measured when there is something in the queue. If %busy is small, large queues and service times probably represent the periodic efforts by the system to ensure that altered blocks are written to the disk in a timely fashion.
Table 36-10 Output from the sar -d Command|
Field Name |
Description |
|---|---|
|
device |
Name of the disk device being monitored |
|
%busy |
Percentage of time the device spent servicing a transfer request |
|
avque |
The sum of the average wait time plus the average service time |
|
r+w/s |
Number of read and write transfers to the device per second |
|
blks/s |
Number of 512-byte blocks transferred to the device per second |
|
avwait |
Average time, in milliseconds, that transfer requests wait idly in the queue (measured only when the queue is occupied) |
|
avserv |
Average time, in milliseconds, for a transfer request to be completed by the device (for disks, this includes seek, rotational latency, and data transfer times) |
Examples--Checking Disk Activity
This abbreviated example illustrates the sar -d output.
$ sar -d
SunOS venus 5.8 Generic sun4u 09/07/99
00:00:00 device %busy avque r+w/s blks/s avwait avserv
01:00:00 fd0 0 0.0 0 0 0.0 0.0
nfs1 0 0.0 0 0 0.0 0.0
sd0 0 0.0 0 0 0.0 39.6
sd0,a 0 0.0 0 0 0.0 39.6
sd0,b 0 0.0 0 0 0.0 0.0
sd0,c 0 0.0 0 0 0.0 0.0
sd0,f 0 0.0 0 0 0.0 0.0
sd0,g 0 0.0 0 0 0.0 0.0
sd0,h 0 0.0 0 0 0.0 0.0
sd6 0 0.0 0 0 0.0 0.0
|
How to Check Page-Out and Memory (sar -g)
Use the sar -g option reports page-out and memory freeing activities (in averages).
$ sar -g 00:00:00 pgout/s ppgout/s pgfree/s pgscan/s %ufs_ipf 01:00:00 0.00 0.00 0.00 0.00 0.00 |
The output displayed by sar -g is a good indicator of whether more memory may be needed. Use the ps -elf command to show the number of cycles used by the page daemon. A high number of cycles, combined with high values for pgfree/s and pgscan/s indicates a memory shortage.
The sar -g command also shows whether inodes are being recycled too quickly, causing a loss of reusable pages.
Output from the -g option is described in the following table.
Table 36-11 Output From the sar -g Command|
Field Name |
Description |
|---|---|
|
pgout/s |
The number of page-out requests per second. |
|
ppgout/s |
The actual number of pages that are paged-out, per second. (A single page-out request may involve paging-out multiple pages.) |
|
pgfree/s |
The number of pages, per second, that are placed on the free list. |
|
pgscan/s |
The number of pages, per second, scanned by the page daemon. If this value is high, the page daemon is spending a lot of time checking for free memory. This implies that more memory may be needed. |
|
%ufs_ipf |
The percentage of ufs inodes taken off the free list by iget that had reusable pages associated with them. These pages are flushed and cannot be reclaimed by processes. Thus, this is the percentage of igets with page flushes. A high value indicates that the free list of inodes is page-bound and the number of ufs inodes may need to be increased. |
Example--Checking Page-Out and Memory
The following abbreviated example shows output from the sar -g command.
$ sar -g SunOS venus 5.8 Generic sun4u 09/07/99 00:00:00 pgout/s ppgout/s pgfree/s pgscan/s %ufs_ipf 01:00:00 0.00 0.00 0.00 0.00 0.00 02:00:02 0.00 0.00 0.00 0.00 0.00 03:00:00 0.00 0.01 0.01 0.00 0.00 04:00:00 0.00 0.00 0.00 0.00 0.00 05:00:01 0.00 0.00 0.00 0.00 0.00 06:00:00 0.00 0.00 0.00 0.00 0.00 Average 0.01 0.12 0.21 0.66 0.00 |
How to Check Kernel Memory Allocation (sar -k)
Use the sar -k command to report on the following activities of the Kernel Memory Allocator (KMA).
The KMA allows a kernel subsystem to allocate and free memory as needed. Rather than statically allocating the maximum amount of memory it is expected to require under peak load, the KMA divides requests for memory into three categories: small (less than 256 bytes), large (512 to 4 Kbytes), and oversized (greater than 4 Kbytes). It keeps two pools of memory to satisfy small and large requests. The oversized requests are satisfied by allocating memory from the system page allocator.
If you are investigating a system that is being used to write drivers or STREAMS that use KMA resources, then sar -k will likely prove useful. Otherwise, you will probably not need the information it provides. Any driver or module that uses KMA resources, but does not specifically return the resources before it exits, can create a memory leak. A memory leak causes the amount of memory allocated by KMA to increase over time. Thus, if the alloc fields of sar -k increase steadily over time, there may be a memory leak. Another indication of a memory leak is failed requests. If this occurs, a memory leak has probably caused KMA to be unable to reserve and allocate memory.
If it appears that a memory leak has occurred, you should check any drivers or STREAMS that may have requested memory from KMA and not returned it.
$ sar -k 00:00:00 sml_mem alloc fail lg_mem alloc fail ovsz_alloc fail 01:00:00 2523136 1866512 0 18939904 14762364 0 360448 0 02:00:02 2523136 1861724 0 18939904 14778748 0 360448 0 |
Output from the -k option is described in the table below.
Table 36-12 Output From the sar -k Command|
Field Name |
Description |
|---|---|
|
sml_mem |
The amount of memory, in bytes, that the KMA has available in the small memory request pool (a small request is less than 256 bytes) |
|
alloc |
The amount of memory, in bytes, that the KMA has allocated from its small memory request pool to small memory requests |
|
fail |
The number of requests for small amounts of memory that failed |
|
lg_mem |
The amount of memory, in bytes, that the KMA has available in the large memory request pool (a large request is from 512 bytes to 4 Kbytes) |
|
alloc |
The amount of memory, in bytes, that the KMA has allocated from its large memory request pool to large memory requests |
|
fail |
The number of failed requests for large amounts of memory |
|
ovsz_alloc |
The amount of memory allocated for oversized requests (those greater than 4 Kbytes); these requests are satisfied by the page allocator--thus, there is no pool |
|
fail |
The number of failed requests for oversized amounts of memory |
Example--Checking Kernel Memory Allocation (sar)
The following is an abbreviated example of sar -k output.
$ sar -k SunOS venus 5.8 Generic sun4u 09/07/99 00:00:00 sml_mem alloc fail lg_mem alloc fail ovsz_alloc fail 01:00:00 2523136 1866512 0 18939904 14762364 0 360448 0 02:00:02 2523136 1861724 0 18939904 14778748 0 360448 0 03:00:00 2523136 1865664 0 18939904 14745884 0 360448 0 04:00:00 2523136 1867692 0 18939904 14746616 0 360448 0 05:00:01 2523136 1867208 0 18939904 14763700 0 360448 0 06:00:00 2523136 1867772 0 18939904 14779444 0 360448 0 Average 2724096 1791806 0 20089344 15434591 0 360448 0 |
How to Check Interprocess Communication (sar -m)
Use the sar -m command to report interprocess communication activities.
$ sar -m 00:00:00 msg/s sema/s 01:00:00 0.00 0.00 |
These figures will usually be zero (0.00), unless you are running applications that use messages or semaphores.
The output from the -m option is described in the table below.
Table 36-13 Output From the sar -m Command|
Field Name |
Description |
|---|---|
|
msg/s |
The number of message operations (sends and receives) per second. |
|
sema/s |
The number of semaphore operations per second. |
Example--Checking Interprocess Communication
The following abbreviated example shows output from the sar -m command.
$ sar -m SunOS venus 5.8 Generic sun4u 09/07/99 00:00:00 msg/s sema/s 01:00:00 0.00 0.00 02:00:02 0.00 0.00 03:00:00 0.00 0.00 04:00:00 0.00 0.00 05:00:01 0.00 0.00 06:00:00 0.00 0.00 Average 0.00 0.00 |
How to Check Page-In Activity (sar -p)
Use the sar -p command to report page-in activity which includes protection and translation faults.
$ sar -p 00:00:00 atch/s pgin/s ppgin/s pflt/s vflt/s slock/s 01:00:00 0.07 0.00 0.00 0.21 0.39 0.00 |
The reported statistics from the -p option are described in the table below.
Table 36-14 Output from the sar -p Command|
Field Name |
Description |
|---|---|
|
atch/s |
The number of page faults, per second, that are satisfied by reclaiming a page currently in memory (attaches per second). Instances of this include reclaiming an invalid page from the free list and sharing a page of text currently being used by another process (for example, two or more processes accessing the same program text). |
|
pgin/s |
The number of times, per second, that file systems receive page-in requests. |
|
ppgin/s |
The number of pages paged in, per second. A single page-in request, such as a soft-lock request (see slock/s), or a large block size, may involve paging-in multiple pages. |
|
pflt/s |
The number of page faults from protection errors. Instances of protection faults are illegal access to a page and "copy-on-writes." Generally, this number consists primarily of "copy-on-writes." |
|
vflt/s |
The number of address translation page faults, per second. These are known as validity faults, and occur when a valid process table entry does not exist for a given virtual address. |
|
slock/s |
The number of faults, per second, caused by software lock requests requiring physical I/O. An example of the occurrence of a soft-lock request is the transfer of data from a disk to memory. The system locks the page that is to receive the data, so that it cannot be claimed and used by another process. |
Example--Checking Page-In Activity
The following abbreviated example shows output from sar -p.
$ sar -p SunOS venus 5.8 Generic sun4u 09/07/99 00:00:00 atch/s pgin/s ppgin/s pflt/s vflt/s slock/s 01:00:00 0.07 0.00 0.00 0.21 0.39 0.00 02:00:02 0.07 0.00 0.00 0.21 0.39 0.00 03:00:00 0.32 0.00 0.00 1.10 2.48 0.00 04:00:00 0.09 0.00 0.00 0.32 0.57 0.00 05:00:01 0.07 0.00 0.00 0.21 0.39 0.00 06:00:00 0.07 0.00 0.00 0.21 0.39 0.00 Average 0.26 0.20 0.30 0.92 1.78 0.00 |
How to Check Queue Activity (sar -q)
Use the sar -q command to report the average queue length while the queue is occupied, and the percentage of time that the queue is occupied.
$ sar -q 00:00:00 runq-sz %runocc swpq-sz %swpocc 01:00:00 |
Note -
The number of LWPs swapped out may greater than zero even if the system has an abundance of free memory. This happens when a sleeping LWP is swapped out and has not been awakened (for example, a process or LWP sleeping, waiting for the keyboard or mouse input).
Output from the -q option is described in the table below.
Table 36-15 Output From the sar -q Command|
Field Name |
Description |
|---|---|
|
runq-sz |
The number of kernel threads in memory waiting for a CPU to run. Typically, this value should be less than 2. Consistently higher values mean that the system may be CPU-bound. |
|
%runocc |
The percentage of time the dispatch queues are occupied. |
|
swpq-sz |
The average number of swapped out LWPs. |
|
%swpocc |
The percentage of time LWPs are swapped out. |
Example--Checking Queue Activity
The following abbreviated example shows output from the sar -q command. If %runocc is high (greater than 90 percent) and runq-sz is greater than 2, the CPU is heavily loaded and response is degraded. In this case, additional CPU capacity may be required to obtain acceptable system response.
$ sar -q SunOS venus 5.8 Generic sun4u 09/07/99 00:00:00 runq-sz %runocc swpq-sz %swpocc 01:00:00 02:00:02 03:00:00 1.0 0 04:00:00 05:00:01 1.0 0 06:00:00 Average 1.3 0 |
How to Check Unused Memory (sar -r)
Use the sar -r command to report the number of memory pages and swap-file disk blocks that are currently unused.
$ sar -r 00:00:00 freemem freeswap 01:00:00 2135 401922 |
Output from the -r option is described in the table below.
Table 36-16 Output From the sar -r Command|
Field Name |
Description |
|---|---|
|
freemem |
The average number of memory pages available to user processes over the intervals sampled by the command. Page size is machine-dependent. |
|
freeswap |
The number of 512-byte disk blocks available for page swapping. |
Example--Checking Unused Memory
The following example shows output from the sar -r command.
$ sar -r SunOS venus 5.8 Generic sun4u 09/07/99 00:00:00 freemem freeswap 01:00:00 2135 401922 02:00:02 2137 401949 03:00:00 2137 402006 04:00:00 2139 401923 05:00:01 2138 402033 06:00:00 2137 401919 Average 2500 399914 |
How to Check CPU Utilization (sar -u)
Display CPU utilization with the sar -u command.
$ sar -u 00:00:00 %usr %sys %wio %idle 01:00:00 0 0 0 100 |
(The sar command without any options is equivalent to sar -u.) At any given moment, the processor is either busy or idle. When busy, the processor is in either user or system mode. When idle, the processor is either waiting for I/O completion or "sitting still" with no work to do.
Output from the -u option is described in the table below.
Table 36-17 Output From the sar -u Command|
Field Name |
Description |
|---|---|
|
%sys |
Lists the percentage of time that the processor is in system mode |
|
%user |
Lists the percentage of time that the processor is in user mode |
|
%wio |
Lists the percentage of time the processor is idle and waiting for I/O completion |
|
%idle |
Lists the percentage of time the processor is idle and is not waiting for I/O |
A high %wio generally means a disk slowdown has occurred.
Example--Checking CPU Utilization
The following example shows output from the sar -u command.
$ sar -u SunOS venus 5.8 Generic sun4u 09/07/99 00:00:00 %usr %sys %wio %idle 01:00:00 0 0 0 100 02:00:02 0 0 0 100 03:00:00 0 0 0 100 04:00:00 0 0 0 100 05:00:01 0 0 0 100 06:00:00 0 0 0 100 07:00:00 0 0 0 100 08:00:01 0 0 0 100 08:20:00 0 0 0 100 08:40:00 0 0 0 100 09:00:00 0 0 0 100 09:20:00 0 0 0 100 09:40:00 0 0 0 100 10:00:00 0 0 0 100 10:20:00 0 0 0 100 10:40:01 0 0 0 100 11:00:00 5 2 10 82 Average 0 0 0 100 |
How to Check System Table Status (sar -v)
Use the sar -v command to report the status of the process table, inode table, file table, and shared memory record table.
$ sar -v 00:00:00 proc-sz ov inod-sz ov file-sz ov lock-sz 01:00:00 43/922 0 2984/4236 0 322/322 0 0/0 |
Output from the -v option is described in the table below.
Table 36-18 Output From the sar -v Command|
Field Name |
Description |
|---|---|
|
proc-sz |
The number of process entries (proc structs) currently being used, or allocated in the kernel. |
|
inod-sz |
The total number of inodes in memory verses the maximum number of inodes allocated in the kernel. This is not a strict high water mark; it can overflow. |
|
file-sz |
The size of the open system file table. The sz is given as 0, since space is allocated dynamically for the file table. |
|
ov |
The number of shared memory record table entries currently being used or allocated in the kernel. The sz is given as 0 because space is allocated dynamically for the shared memory record table. |
|
lock-sz |
The number of shared memory record table entries currently being used or allocated in the kernel. The sz is given as 0 because space is allocated dynamically for the shared memory record table. |
Example--Checking System Table Status
The following abbreviated example shows output from the sar -v command. This example shows that all tables are large enough to have no overflows. These tables are all dynamically allocated based on the amount of physical memory.
$ sar -v SunOS venus 5.8 Generic sun4u 09/07/99 00:00:00 proc-sz ov inod-sz ov file-sz ov lock-sz 01:00:00 43/922 0 2984/4236 0 322/322 0 0/0 02:00:02 43/922 0 2984/4236 0 322/322 0 0/0 03:00:00 43/922 0 2986/4236 0 323/323 0 0/0 04:00:00 43/922 0 2987/4236 0 322/322 0 0/0 05:00:01 43/922 0 2987/4236 0 322/322 0 0/0 06:00:00 43/922 0 2987/4236 0 322/322 0 0/0 |
How to Check Swap Activity (sar -w)
Use the sar -w command to report swapping and switching activity.
$ sar -w 00:00:00 swpin/s bswin/s swpot/s bswot/s pswch/s 01:00:00 0.00 0.0 0.00 0.0 22 |
Target values and observations are described in the table below.
Table 36-19 Output From the sar -w Command|
Field Name |
Description |
|---|---|
|
swpin/s |
The number of LWP transfers into memory per second. |
|
bswin/s |
The average number of processes swapped out of memory per second. If the number is greater than 1, you may need to increase memory. |
|
swpot/s |
The average number of processes swapped out of memory per second. If the number is greater than 1, you may need to increase memory. |
|
bswot/s |
The number of blocks transferred for swap-outs per second. |
|
pswch/s |
The number of kernel thread switches per second. |
Note -
All process swap-ins include process initialization.
Example--Checking Swap Activity
The following example shows output from the sar -w command.
$ sar -w SunOS venus 5.8 Generic sun4u 09/07/99 00:00:00 swpin/s bswin/s swpot/s bswot/s pswch/s 01:00:00 0.00 0.0 0.00 0.0 22 02:00:02 0.00 0.0 0.00 0.0 22 03:00:00 0.00 0.0 0.00 0.0 22 04:00:00 0.00 0.0 0.00 0.0 22 05:00:01 0.00 0.0 0.00 0.0 22 06:00:00 0.00 0.0 0.00 0.0 22 07:00:00 0.00 0.0 0.00 0.0 22 08:00:01 0.00 0.0 0.00 0.0 22 08:20:00 0.00 0.0 0.00 0.0 22 08:40:00 0.00 0.0 0.00 0.0 22 09:00:00 0.00 0.0 0.00 0.0 22 09:20:00 0.00 0.0 0.00 0.0 22 09:40:00 0.00 0.0 0.00 0.0 22 10:00:00 0.00 0.0 0.00 0.0 22 10:20:00 0.00 0.0 0.00 0.0 22 10:40:01 0.00 0.0 0.00 0.0 23 11:00:00 0.00 0.0 0.00 0.0 144 Average 0.00 0.0 0.00 0.0 24 |
How to Check Terminal Activity (sar -y)
Use the sar -y command to monitor terminal device activities.
$ sar -y 00:00:00 rawch/s canch/s outch/s rcvin/s xmtin/s mdmin/s 01:00:00 0 0 0 0 0 0 |
If you have a lot of terminal I/O, you can use this report to determine if there are any bad lines. The activities recorded are defined in the table below.
Table 36-20 Output From the sar -y Command|
Field Name |
Description |
|---|---|
|
rawch/s |
Input characters (raw queue), per second |
|
canch/s |
Input characters processed by canon (canonical queue) per second |
|
outch/s |
Output characters (output queue) per second |
|
rcvin/s |
Receiver hardware interrupts per second |
|
xmtin/s |
Transmitter hardware interrupts per second |
|
mdmin/s |
Modem interrupts per second |
The number of modem interrupts per second (mdmin/s) should be close to zero, and the receive and transmit interrupts per second (xmtin/s and rcvin/s) should be less than or equal to the number of incoming or outgoing characters, respectively. If this is not the case, check for bad lines.
Example--Checking Terminal Activity
The following abbreviated example shows output from the sar -y command.
$ sar -y SunOS venus 5.8 Generic sun4u 09/07/99 00:00:00 rawch/s canch/s outch/s rcvin/s xmtin/s mdmin/s 01:00:00 0 0 0 0 0 0 02:00:02 0 0 0 0 0 0 03:00:00 0 0 0 0 0 0 04:00:00 0 0 0 0 0 0 05:00:01 0 0 0 0 0 0 06:00:00 0 0 0 0 0 0 07:00:00 0 0 0 0 0 0 08:00:01 0 0 0 0 0 0 08:20:00 0 0 0 0 0 0 08:40:00 0 0 0 0 0 0 09:00:00 0 0 0 0 0 0 09:20:00 0 0 0 0 0 0 09:40:00 0 0 0 0 0 0 10:00:00 0 0 0 0 0 0 10:20:00 0 0 0 0 0 0 10:40:01 0 0 20 0 0 0 Average 0 0 3 0 0 0 |
How to Check Overall System Performance (sar -A)
Use the sar -A command to display a view of overall system performance.
This provides a more global perspective. If data from more than one time segment is shown, the report includes averages.
Collecting System Activity Data Automatically (sar)
Three commands are involved in automatic system activity data collection: sadc, sa1, and sa2.
The sadc data collection utility periodically collects data on system activity and saves it in a file in binary format--one file for each 24-hour period. You can set up sadc to run periodically (usually once each hour), and whenever the system boots to multiuser mode. The data files are placed in the directory /usr/adm/sa. Each file is named sadd, where dd is the current date. The format of the command is as follows:
/usr/lib/sa/sadc [t n] [ofile] |
The command samples n times with an interval of t seconds (t should be greater than 5 seconds) between samples. It then writes, in binary format, to the file ofile, or to standard output. If t and n are omitted, a special file is written once.
Running sadc When Booting
The sadc command should be run at system boot time in order to record the statistics from when the counters are reset to zero. To make sure that sadc is run at boot time, the /etc/init.d/perf file must contain a command line that writes a record to the daily data file.
The command entry has the following format:
su sys -c "/usr/lib/sa/sadc /usr/adm/sa/sa`date +5d`" |
Running sadc Periodically With sa1
To generate periodic records, you need to run sadc regularly. The simplest way to do this is by putting a line into the /var/spool/cron/sys file, which calls the shell script, sa1. This script invokes sadc and writes to the daily data files, /var/adm/sa/sadd. It has the following format:
/usr/lib/sa/sa1 [t n] |
The arguments t and n cause records to be written n times at an interval of t seconds. If these arguments are omitted, the records are written only one time.
Producing Reports With sa2
Another shell script, sa2, produces reports rather than binary data files. The sa2 command invokes the sar command and writes the ASCII output to a report file.
Collecting System Activity Data (sar)
The sar command can be used either to gather system activity data itself or to report what has been collected in the daily activity files created by sadc.
The sar command has the following formats:
sar [-aAbcdgkmpqruvwy] [-o file] t [n] |
sar [-aAbcdgkmpqruvwy] [-s time] [-e time] [-i sec] [-f file] |
The sar command below samples cumulative activity counters in the operating system every t seconds, n times. (t should be 5 seconds or greater; otherwise, the command itself may affect the sample.) You must specify a time interval between which to take the samples; otherwise, the command operates according to the second format. The default value of n is 1. The following example takes two samples separated by 10 seconds. If the -o option is specified, samples are saved in file in binary format.
$ sar -u 10 2 |
Other important information about the sar command:
-
With no sampling interval or number of samples specified, sar extracts data from a previously recorded file, either the one specified by the -f option or, by default, the standard daily activity file, /var/adm/sa/sadd, for the most recent day.
-
The -s and -e options define the starting and ending times for the report. Starting and ending times are of the form hh[:mm[:ss]] (where h, m, and s represent hours, minutes, and seconds).
-
The -i option specifies, in seconds, the intervals between record selection. If the -i option is not included, all intervals found in the daily activity file are reported.
The table below lists the sar options and their actions.
Table 36-21 Options for sar Command|
Option |
Actions |
|---|---|
|
-a |
Checks file access operations |
|
-b |
Checks buffer activity |
|
-c |
Checks system calls |
|
-d |
Checks activity for each block device |
|
-g |
Checks page-out and memory freeing |
|
-k |
Checks kernel memory allocation |
|
-m |
Checks interprocess communication |
|
-p |
Checks swap and dispatch activity |
|
-q |
Checks queue activity |
|
-r |
Checks unused memory |
|
-u |
Checks CPU utilization |
|
-nv |
Checks system table status |
|
-w |
Checks swapping and switching volume |
|
-y |
Checks terminal activity |
|
-A |
Reports overall system performance (same as entering all options) |
If no option is used, it is equivalent to calling the command with the -u option.
How to Set Up Automatic Data Collection
-
Edit the /etc/init.d/perf file and uncomment all lines:
This version of the sadc command writes a special record that marks the time when the counters are reset to zero (boot time). The sadc output is put into the file sadd (where dd is the current date), which acts as the daily system activity record.
-
Edit the /var/spool/cron/crontabs/sys file (the system crontab file) and uncomment the following lines:
# 0 * * * 0-6 /usr/lib/sa/sa1 # 20,40 8-17 * * 1-5 /usr/lib/sa/sa1 # 5 18 * * 1-5 /usr/lib/sa/sa2 -s 8:00 -e 18:01 -i 1200 -A
The first entry writes a record to /var/adm/sa/sadd on the hour, every hour, seven days a week.
The second entry writes a record to /var/adm/sa/sadd twice each hour during peak working hours: at 20 minutes and 40 minutes past the hour, from 8 a.m. to 5 p.m., Monday through Friday.
Thus, these two crontab entries cause a record to be written to /var/adm/sa/sadd every 20 minutes from 8 a.m. to 5 p.m., Monday through Friday, and every hour on the hour otherwise. You can change these defaults to meet your needs.
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