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view usr/src/man/man1m/trapstat.1m @ 13659:57451298f940
1469 ttyc/ttyd should be an allowed console device
Reviewed by: Milan Jurik <milan.jurik@xylab.cz>
Reviewed by: Alexander Eremin <alexander.r.eremin@gmail.com>
Approved by: Richard Lowe <richlowe@richlowe.net>
| author | Gary Mills <gary_mills@fastmail.fm> |
|---|---|
| date | Thu, 05 Apr 2012 08:47:21 -0500 |
| parents | 5b2854ecc12d |
| children |
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'\" te .\" Copyright (c) 2004, Sun Microsystems, Inc. All Rights Reserved. .\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License"). You may not use this file except in compliance with the License. .\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing. See the License for the specific language governing permissions and limitations under the License. .\" When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner] .TH TRAPSTAT 1M "May 11, 2004" .SH NAME trapstat \- report trap statistics .SH SYNOPSIS .LP .nf \fB/usr/sbin/trapstat\fR [\fB-t\fR | \fB-T\fR | \fB-e\fR \fIentry\fR] [\fB-C\fR \fIprocessor_set_id\fR | \fB-c\fR \fIcpulist\fR] [\fB-P\fR] [\fB-a\fR] [\fB-r\fR \fIrate\fR] [ [\fIinterval\fR [\fIcount\fR]] | \fIcommand\fR | [\fIargs\fR]] .fi .LP .nf \fB/usr/sbin/trapstat\fR \fB-l\fR .fi .SH DESCRIPTION .sp .LP The \fBtrapstat\fR utility gathers and displays run-time trap statistics on UltraSPARC-based systems. The default output is a table of trap types and \fBCPU\fR \fBID\fRs, with each row of the table denoting a trap type and each column of the table denoting a \fBCPU\fR. If standard output is a terminal, the table contains as many columns of data as can fit within the terminal width; if standard output is not a terminal, the table contains at most six columns of data. By default, data is gathered and and displayed for all \fBCPU\fRs; if the data cannot fit in a single table, it is printed across multiple tables. The set of \fBCPU\fRs for which data is gathered and displayed can be optionally specified with the \fB-c\fR or \fB-C\fR option. .sp .LP Unless the \fB-r\fR option or the \fB-a\fR option is specified, the value displayed in each entry of the table corresponds to the number of traps per second. If the \fB-r\fR option is specified, the value corresponds to the number of traps over the interval implied by the specified sampling rate; if the \fB-a\fR option is specified, the value corresponds to the accumulated number of traps since the invocation of \fBtrapstat\fR. .sp .LP By default, \fBtrapstat\fR displays data once per second, and runs indefinitely; both of these behaviors can be optionally controlled with the \fIinterval\fR and \fIcount\fR parameters, respectively. The \fIinterval\fR is specified in seconds; the \fIcount\fR indicates the number of intervals to be executed before exiting. Alternatively, \fBcommand\fR can be specified, in which case \fBtrapstat\fR executes the provided command and continues to run until the command exits. A positive integer is assumed to be an \fIinterval\fR; if the desired \fB\fIcommand\fR\fR cannot be distinguished from an integer, the full path of \fIcommand\fR must be specified. .sp .LP UltraSPARC I (obsolete), II, and III handle translation lookaside buffer (TLB) misses by trapping to the operating system. TLB miss traps can be a significant component of overall system performance for some workloads; the \fB-t\fR option provides in-depth information on these traps. When run with this option, \fBtrapstat\fR displays both the rate of TLB miss traps \fI\fR and the percentage of time spent processing those traps. Additionally, TLB misses that hit in the translation storage buffer (TSB) are differentiated from TLB misses that further miss in the TSB. (The TSB is a software structure used as a translation entry cache to allow the TLB to be quickly filled; it is discussed in detail in the \fIUltraSPARC II User's Manual\fR.) The TLB and TSB miss information is further broken down into user- and kernel-mode misses. .sp .LP Workloads with working sets that exceed the TLB reach may spend a significant amount of time missing in the TLB. To accommodate such workloads, the operating system supports multiple page sizes: larger page sizes increase the effective TLB reach and thereby reduce the number of TLB misses. To provide insight into the relationship between page size and TLB miss rate, \fBtrapstat\fR optionally provides in-depth TLB miss information broken down by page size using the \fB-T\fR option. The information provided by the \fB-T\fR option is a superset of that provided by the \fB-t\fR option; only one of \fB-t\fR and \fB-T\fR can be specified. .SH OPTIONS .sp .LP The following options are supported: .sp .ne 2 .na \fB\fB-a\fR\fR .ad .RS 24n Displays the number of traps as accumulating, monotonically increasing values instead of per-second or per-interval rates. .RE .sp .ne 2 .na \fB\fB-c\fR \fIcpulist\fR \fR .ad .RS 24n Enables \fBtrapstat\fR only on the \fBCPU\fRs specified by \fIcpulist\fR. .sp \fIcpulist\fR can be a single processor \fBID\fR (for example, \fB4\fR), a range of processor\fB ID\fRs (for example, \fB4-6\fR), or a comma separated list of processor\fB ID\fRs or processor \fBID\fR ranges (for example, \fB4,5,6\fR or \fB4,6-8\fR). .RE .sp .ne 2 .na \fB\fB-C\fR \fIprocessor_set_id\fR \fR .ad .RS 24n Enables \fBtrapstat\fR only on the \fBCPU\fRs in the processor set specified by \fIprocessor_set_id\fR. .sp \fBtrapstat\fR modifies its output to always reflect the \fBCPU\fRs in the specified processor set. If a \fBCPU\fR is added to the set, \fBtrapstat\fR modifies its output to include the added \fBCPU\fR; if a \fBCPU\fR is removed from the set, \fBtrapstat\fR modifies its output to exclude the removed CPU. At most one processor set can be specified. .RE .sp .ne 2 .na \fB\fB-e\fR \fIentrylist\fR \fR .ad .RS 24n Enables \fBtrapstat\fR only for the trap table entry or entries specified by \fIentrylist\fR. A trap table entry can be specified by trap number or by trap name (for example, the level-10 trap can be specified as \fB74\fR, \fB0x4A\fR, \fB0x4a\fR, or \fBlevel-10\fR). .sp \fIentrylist\fR can be a single trap table entry or a comma separated list of trap table entries. If the specified trap table entry is not valid, \fBtrapstat\fR prints a table of all valid trap table entries and values. A list of valid trap table entries is also found in \fIThe SPARC Architecture Manual, Version 9\fR and the \fISun Microelectronics UltraSPARC II User's Manual.\fR If the parsable option (\fB-P\fR) is specified in addition to the \fB-e\fR option, the format of the data is as follows: .sp .sp .TS c c l l . Field Contents 1 Timestamp (nanoseconds since start) 2 CPU ID 3 Trap number (in hexadecimal) 4 Trap name 5 Trap rate per interval .TE Each field is separated with whitespace. If the format is modified, it will be modified by adding potentially new fields beginning with field 6; exant fields will remain unchanged. .RE .sp .ne 2 .na \fB\fB-l\fR \fR .ad .RS 24n Lists trap table entries. By default, a table is displayed containing all valid trap numbers, their names and a brief description. The trap name is used in both the default output and in the \fIentrylist\fR parameter for the \fB-e\fR argument. If the parsable option (\fB-P\fR) is specified in addition to the \fB-l\fR option, the format of the data is as follows: .sp .sp .TS c c l l . Field Contents 1 Trap number in hexadecimal 2 Trap number in decimal 3 Trap name Remaining Trap description .TE .RE .sp .ne 2 .na \fB\fB-P\fR \fR .ad .RS 24n Generates parsable output. When run without other data gathering modifying options (that is, \fB-e\fR, \fB-t\fR or \fB-T\fR), \fBtrapstat\fR's the parsable output has the following format: .sp .sp .TS c c l l . Field Contents 1 Timestamp (nanoseconds since start) 2 CPU ID 3 Trap number (in hexadecimal) 4 Trap name 5 Trap rate per interval .TE Each field is separated with whitespace. If the format is modified, it will be modified by adding potentially new fields beginning with field 6; extant fields will remain unchanged. .RE .sp .ne 2 .na \fB\fB-r\fR \fIrate\fR \fR .ad .RS 24n Explicitly sets the sampling rate to be \fIrate\fR samples per second. If this option is specified, \fBtrapstat\fR's output changes from a traps-per-second to traps-per-sampling-interval. .RE .sp .ne 2 .na \fB\fB-t\fR\fR .ad .RS 24n Enables TLB statistics. .sp A table is displayed with four principal columns of data: \fIitlb-miss\fR, \fIitsb-miss\fR, \fIdtlb-miss\fR, and \fIdtsb-miss\fR. The columns contain both the rate of the corresponding event and the percentage of \fBCPU\fR time spent processing the event. The percentage of \fBCPU\fR time is given only in terms of a single \fBCPU\fR. The rows of the table correspond to \fBCPU\fRs, with each \fBCPU\fR consuming two rows: one row for user-mode events (denoted with \fBu\fR) and one row for kernel-mode events (denoted with \fBk\fR). For each row, the percentage of \fBCPU\fR time is totalled and displayed in the rightmost column. The \fBCPU\fRs are delineated with a solid line. If the parsable option (\fB-P\fR) is specified in addition to the \fB-t\fR option, the format of the data is as follows: .sp .sp .TS c c l l . Field Contents 1 Timestamp (nanoseconds since start) 2 CPU ID 3 Mode (\fBk\fR denotes kernel, \fBu\fR denotes user) 4 I-TLB misses 5 Percentage of time in I-TLB miss handler 6 I-TSB misses 7 Percentage of time in I-TSB miss handler 8 D-TLB misses 9 Percentage of time in D-TLB miss handler 10 D-TSB misses 11 Percentage of time in D-TSB miss handler .TE Each field is separated with whitespace. If the format is modified, it will be modified by adding potentially new fields beginning with field 12; extant fields will remain unchanged. .RE .sp .ne 2 .na \fB\fB-T\fR \fR .ad .RS 24n Enables \fBTLB\fR statistics, with page size information. As with the \fB-t\fR option, a table is displayed with four principal columns of data: \fIitlb-miss\fR, \fIitsb-miss\fR, \fIdtlb-miss\fR, and \fIdtsb-miss\fR. The columns contain both the absolute number of the corresponding event, and the percentage of \fBCPU\fR time spent processing the event. The percentage of \fBCPU\fR time is given only in terms of a single \fBCPU\fR. The rows of the table correspond to \fBCPU\fRs, with each \fBCPU\fR consuming two sets of rows: one set for user-level events (denoted with \fBu\fR) and one set for kernel-level events (denoted with \fBk\fR). Each set, in turn, contains as many rows as there are page sizes supported (see \fBgetpagesizes\fR(3C)). For each row, the percentage of \fBCPU\fR time is totalled and displayed in the right-most column. The two sets are delineated with a dashed line; CPUs are delineated with a solid line. If the parsable option (\fB-P\fR) is specified in addition to the \fB-T\fR option, the format of the data is as follows: .sp .sp .TS c c l l . Field Contents 1 Timestamp (nanoseconds since start) 2 CPU ID 3 Mode \fBk\fR denotes kernel, \fBu\fR denotes user) 4 Page size, in decimal 5 I-TLB misses 6 Percentage of time in I-TLB miss handler 7 I-TSB misses 8 Percentage of time in I-TSB miss handler 9 D-TLB misses 10 Percentage of time in D-TLB miss handler 11 D-TSB misses 12 Percentage of time in D-TSB miss handler .TE Each field is separated with whitespace. If the format is modified, it will be modified by adding potentially new fields beginning with field 13; extant fields will remain unchanged. .RE .SH EXAMPLES .LP \fBExample 1 \fRUsing \fBtrapstat\fR Without Options .sp .LP When run without options, \fBtrapstat\fR displays a table of trap types and CPUs. At most six columns can fit in the default terminal width; if (as in this example) there are more than six CPUs, multiple tables are displayed: .sp .in +2 .nf example# \fBtrapstat\fR vct name | cpu0 cpu1 cpu4 cpu5 cpu8 cpu9 ------------------------+------------------------------------------------------ 24 cleanwin | 6446 4837 6368 2153 2623 1321 41 level-1 | 100 0 0 0 1 0 44 level-4 | 0 1 1 1 0 0 45 level-5 | 0 0 0 0 0 0 47 level-7 | 0 0 0 0 9 0 49 level-9 | 100 100 100 100 100 100 4a level-10 | 100 0 0 0 0 0 4d level-13 | 6 10 7 16 13 11 4e level-14 | 100 0 0 0 1 0 60 int-vec | 2607 2740 2642 2922 2920 3033 64 itlb-miss | 3129 2475 3167 1037 1200 569 68 dtlb-miss | 121061 86162 109838 37386 45639 20269 6c dtlb-prot | 997 847 1061 379 406 184 84 spill-user-32 | 2809 2133 2739 200806 332776 454504 88 spill-user-64 | 45819 207856 93487 228529 68373 77590 8c spill-user-32-cln | 784 561 767 274 353 215 90 spill-user-64-cln | 9 37 17 39 12 13 98 spill-kern-64 | 62913 50145 63869 21916 28431 11738 a4 spill-asuser-32 | 1327 947 1288 460 572 335 a8 spill-asuser-64 | 26 48 18 54 10 14 ac spill-asuser-32-cln | 4580 3599 4555 1538 1978 857 b0 spill-asuser-64-cln | 26 0 0 2 0 0 c4 fill-user-32 | 2862 2161 2798 191746 318115 435850 c8 fill-user-64 | 45813 197781 89179 217668 63905 74281 cc fill-user-32-cln | 3802 2833 3733 10153 16419 19475 d0 fill-user-64-cln | 329 10105 4873 10603 4235 3649 d8 fill-kern-64 | 62519 49943 63611 21824 28328 11693 108 syscall-32 | 2285 1634 2278 737 957 383 126 self-xcall | 100 0 0 0 0 0 vct name | cpu12 cpu13 cpu14 cpu15 ------------------------+------------------------------------ 24 cleanwin | 5435 4232 6302 6104 41 level-1 | 0 0 0 0 44 level-4 | 2 0 0 1 45 level-5 | 0 0 0 0 47 level-7 | 0 0 0 0 49 level-9 | 100 100 100 100 4a level-10 | 0 0 0 0 4d level-13 | 15 11 22 11 4e level-14 | 0 0 0 0 60 int-vec | 2813 2833 2738 2714 64 itlb-miss | 2636 1925 3133 3029 68 dtlb-miss | 90528 70639 107786 103425 6c dtlb-prot | 819 675 988 954 84 spill-user-32 | 175768 39933 2811 2742 88 spill-user-64 | 0 241348 96907 118298 8c spill-user-32-cln | 681 513 753 730 90 spill-user-64-cln | 0 42 16 20 98 spill-kern-64 | 52158 40914 62305 60141 a4 spill-asuser-32 | 1113 856 1251 1208 a8 spill-asuser-64 | 0 64 16 24 ac spill-asuser-32-cln | 3816 2942 4515 4381 b0 spill-asuser-64-cln | 0 0 0 0 c4 fill-user-32 | 170744 38444 2876 2784 c8 fill-user-64 | 0 230381 92941 111694 cc fill-user-32-cln | 8550 3790 3612 3553 d0 fill-user-64-cln | 0 10726 4495 5845 d8 fill-kern-64 | 51968 40760 62053 59922 108 syscall-32 | 1839 1495 2144 2083 126 self-xcall | 0 0 0 0 .fi .in -2 .sp .LP \fBExample 2 \fRUsing \fBtrapset\fR with CPU Filtering .sp .LP The \fB-c\fR option can be used to limit the \fBCPU\fRs on which \fBtrapstat\fR is enabled. This example limits \fBCPU 1\fR and \fBCPU\fRs \fB12\fR through \fB15\fR. .sp .in +2 .nf example# \fBtrapstat -c 1,12-15\fR vct name | cpu1 cpu12 cpu13 cpu14 cpu15 ------------------------+--------------------------------------------- 24 cleanwin | 6923 3072 2500 3518 2261 44 level-4 | 3 0 0 1 1 49 level-9 | 100 100 100 100 100 4d level-13 | 23 8 14 19 14 60 int-vec | 2559 2699 2752 2688 2792 64 itlb-miss | 3296 1548 1174 1698 1087 68 dtlb-miss | 114788 54313 43040 58336 38057 6c dtlb-prot | 1046 549 417 545 370 84 spill-user-32 | 66551 29480 301588 26522 213032 88 spill-user-64 | 0 318652 111239 299829 221716 8c spill-user-32-cln | 856 347 331 416 293 90 spill-user-64-cln | 0 55 21 59 39 98 spill-kern-64 | 66464 31803 24758 34004 22277 a4 spill-asuser-32 | 1423 569 560 698 483 a8 spill-asuser-64 | 0 74 32 98 46 ac spill-asuser-32-cln | 4875 2250 1728 2384 1584 b0 spill-asuser-64-cln | 0 2 0 1 0 c4 fill-user-32 | 64193 28418 287516 27055 202093 c8 fill-user-64 | 0 305016 106692 288542 210654 cc fill-user-32-cln | 6733 3520 15185 2396 12035 d0 fill-user-64-cln | 0 13226 3506 12933 11032 d8 fill-kern-64 | 66220 31680 24674 33892 22196 108 syscall-32 | 2446 967 817 1196 755 .fi .in -2 .sp .LP \fBExample 3 \fRUsing \fBtrapstat\fR with TLB Statistics .sp .LP The \fB-t\fR option displays in-depth \fBTLB\fR statistics, including the amount of time spent performing \fBTLB\fR miss processing. The following example shows that the machine is spending 14.1 percent of its time just handling D-TLB misses: .sp .in +2 .nf example# \fBtrapstat -t\fR cpu m| itlb-miss %tim itsb-miss %tim | dtlb-miss %tim dtsb-miss %tim |%tim -----+-------------------------------+-------------------------------+---- 0 u| 2571 0.3 0 0.0 | 10802 1.3 0 0.0 | 1.6 0 k| 0 0.0 0 0.0 | 106420 13.4 184 0.1 |13.6 -----+-------------------------------+-------------------------------+---- 1 u| 3069 0.3 0 0.0 | 10983 1.2 100 0.0 | 1.6 1 k| 27 0.0 0 0.0 | 106974 12.6 19 0.0 |12.7 -----+-------------------------------+-------------------------------+---- 2 u| 3033 0.3 0 0.0 | 11045 1.2 105 0.0 | 1.6 2 k| 43 0.0 0 0.0 | 107842 12.7 108 0.0 |12.8 -----+-------------------------------+-------------------------------+---- 3 u| 2924 0.3 0 0.0 | 10380 1.2 121 0.0 | 1.6 3 k| 54 0.0 0 0.0 | 102682 12.2 16 0.0 |12.2 -----+-------------------------------+-------------------------------+---- 4 u| 3064 0.3 0 0.0 | 10832 1.2 120 0.0 | 1.6 4 k| 31 0.0 0 0.0 | 107977 13.0 236 0.1 |13.1 =====+===============================+===============================+==== ttl | 14816 0.3 0 0.0 | 585937 14.1 1009 0.0 |14.5 .fi .in -2 .sp .LP \fBExample 4 \fRUsing \fBtrapstat\fR with TLB Statistics and Page Size Information .sp .LP By specifying the \fB-T\fR option, \fBtrapstat\fR shows \fBTLB\fR misses broken down by page size. In this example, CPU 0 is spending 7.9 percent of its time handling user-mode TLB misses on 8K pages, and another 2.3 percent of its time handling user-mode TLB misses on 64K pages. .sp .in +2 .nf example# \fBtrapstat -T -c 0\fR cpu m size| itlb-miss %tim itsb-miss %tim | dtlb-miss %tim dtsb-miss %tim |%tim ----------+-------------------------------+-------------------------------+---- 0 u 8k| 1300 0.1 15 0.0 | 104897 7.9 90 0.0 | 8.0 0 u 64k| 0 0.0 0 0.0 | 29935 2.3 7 0.0 | 2.3 0 u 512k| 0 0.0 0 0.0 | 3569 0.2 2 0.0 | 0.2 0 u 4m| 0 0.0 0 0.0 | 233 0.0 2 0.0 | 0.0 - - - - - + - - - - - - - - - - - - - - - + - - - - - - - - - - - - - - - + - - 0 k 8k| 13 0.0 0 0.0 | 71733 6.5 110 0.0 | 6.5 0 k 64k| 0 0.0 0 0.0 | 0 0.0 0 0.0 | 0.0 0 k 512k| 0 0.0 0 0.0 | 0 0.0 206 0.1 | 0.1 0 k 4m| 0 0.0 0 0.0 | 0 0.0 0 0.0 | 0.0 ==========+===============================+===============================+==== ttl | 1313 0.1 15 0.0 | 210367 17.1 417 0.2 |17.5 .fi .in -2 .sp .LP \fBExample 5 \fRUsing \fBtrapstat\fR with Entry Filtering .sp .LP By specifying the \fB-e\fR option, \fBtrapstat\fR displays statistics for only specific trap types. Using this option minimizes the probe effect when seeking specific data. This example yields statistics for only the \fIdtlb-prot\fR and \fIsyscall-32\fR traps on CPUs 12 through 15: .sp .in +2 .nf example# \fBtrapstat -e dtlb-prot,syscall-32 -c 12-15\fR vct name | cpu12 cpu13 cpu14 cpu15 ------------------------+------------------------------------ 6c dtlb-prot | 817 754 1018 560 108 syscall-32 | 1426 1647 2186 1142 vct name | cpu12 cpu13 cpu14 cpu15 ------------------------+------------------------------------ 6c dtlb-prot | 1085 996 800 707 108 syscall-32 | 2578 2167 1638 1452 .fi .in -2 .sp .LP \fBExample 6 \fRUsing \fBtrapstat\fR with a Higher Sampling Rate .sp .LP The following example uses the \fB-r\fR option to specify a sampling rate of 1000 samples per second, and filter only for the level-10 trap. Additionally, specifying the \fB-P\fR option yields parsable output. .sp .LP Notice the timestamp difference between the level-10 events: 9,998,000 nanoseconds and 10,007,000 nanoseconds. These level-10 events correspond to the system clock, which by default ticks at 100 hertz (that is, every 10,000,000 nanoseconds). .sp .in +2 .nf example# \fBtrapstat -e level-10 -P -r 1000\fR 1070400 0 4a level-10 0 2048600 0 4a level-10 0 3030400 0 4a level-10 1 4035800 0 4a level-10 0 5027200 0 4a level-10 0 6027200 0 4a level-10 0 7027400 0 4a level-10 0 8028200 0 4a level-10 0 9026400 0 4a level-10 0 10029600 0 4a level-10 0 11028600 0 4a level-10 0 12024000 0 4a level-10 0 13028400 0 4a level-10 1 14031200 0 4a level-10 0 15027200 0 4a level-10 0 16027600 0 4a level-10 0 17025000 0 4a level-10 0 18026000 0 4a level-10 0 19027800 0 4a level-10 0 20025600 0 4a level-10 0 21025200 0 4a level-10 0 22025000 0 4a level-10 0 23035400 0 4a level-10 1 24027400 0 4a level-10 0 25026000 0 4a level-10 0 26027000 0 4a level-10 0 .fi .in -2 .sp .SH ATTRIBUTES .sp .LP See \fBattributes\fR(5) for descriptions of the following attributes: .sp .sp .TS box; c c l l . ATTRIBUTE TYPE ATTRIBUTE VALUE Interface Stability Human Readable Output Unstable Parsable Output Evolving .TE .SH SEE ALSO .sp .LP \fBlockstat\fR(1M), \fBpmap\fR(1), \fBpsrset\fR(1M), \fBpsrinfo\fR(1M), \fBpbind\fR(1M), \fBppgsz\fR(1), \fBgetpagesizes\fR(3C) .sp .LP \fISun Microelectronics UltraSPARC II User's Manual,\fR January 1997, STP1031, .sp .LP \fIThe SPARC Architecture Manual, Version 9,\fR 1994, Prentice-Hall. .SH NOTES .sp .LP When enabled, \fBtrapstat\fR induces a varying probe effect, depending on the type of information collected. While the precise probe effect depends upon the specifics of the hardware, the following table can be used as a rough guide: .sp .sp .TS c c l l . Option Approximate probe effect default 3-5% per trap \fB-e\fR 3-5% per specified trap \fB-t\fR, \fB-T\fR T{ 40-45% per TLB miss trap hitting in the TSB, 25-30% per TLB miss trap missing in the TSB T} .TE .sp .LP These probe effects are \fIper trap\fR not for the system as a whole. For example, running \fBtrapstat\fR with the default options on a system that spends 7% of total time handling traps induces a performance degradation of less than one half of one percent; running \fBtrapstat\fR with the \fB-t\fR or \fB-T\fR option on a system spending 5% of total time processing TLB misses induce a performance degradation of no more than 2.5%. .sp .LP When run with the \fB-t\fR or \fB-T\fR option, \fBtrapstat\fR accounts for its probe effect when calculating the \fI%tim\fR fields. This assures that the \fI%tim\fR fields are a reasonably accurate indicator of the time a given workload is spending handling TLB misses \(em regardless of the perturbing presence of \fBtrapstat\fR. .sp .LP While the \fI%tim\fR fields include the explicit cost of executing the TLB miss handler, they do \fInot\fR include the implicit costs of TLB miss traps (for example, pipeline effects, cache pollution, etc). These implicit costs become more significant as the trap rate grows; if high \fI%tim\fR values are reported (greater than 50%), you can accurately infer that much of the balance of time is being spent on the implicit costs of the TLB miss traps. .sp .LP Due to the potential system wide degradation induced, only the super-user can run \fBtrapstat\fR. .sp .LP Due to the limitation of the underlying statistics gathering methodology, only one instance of \fBtrapstat\fR can run at a time.