trapstat - report trap statistics trapstat
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System Administration Commands trapstat(1M) NAME trapstat - report trap statistics SYNOPSIS /usr/sbin/trapstat [-t | -T | -e entry] [-C processor_set_id | -c cpulist] [-P] [-a] [-A cor|soc|bins [-m]] [-k keys] [-o num] [-r rate | [interval [count]] | command [args]...] /usr/sbin/trapstat -O statfile [-t | -T | -e entry] [-C processor_set_id | -c cpulist] [-a] [-r rate | [interval [count]] | command [args]...] /usr/sbin/trapstat -I statfile [-A cor|soc|bins [-m]] [-k keys] [-o num] /usr/sbin/trapstat -l [-P] [-t | -T] DESCRIPTION The trapstat utility gathers and displays run-time trap statistics on UltraSPARC-based systems. The default output is a table of trap types and CPU IDs, with each row of the table denoting a trap type and each column of the table denoting a CPU. If standard output is a terminal, the table contains as many columns of data as can fit within the termi- nal width; if standard output is not a terminal, the table contains at most six columns of data. By default, data is gathered and and dis- played for all CPUs; if the data cannot fit in a single table, it is printed across multiple tables. The set of CPUs for which data is gath- ered and displayed can be optionally specified with the -c or -C option. Unless the -r option or the -a option or a command argument is speci- fied, the value displayed in each entry of the table corresponds to the number of traps per second. If the -r option is specified, the value corresponds to the number of traps over the interval implied by the specified sampling rate; if the -a option is specified, the value cor- responds to the accumulated number of traps since the invocation of trapstat. If a command argument is specified, then the value corre- sponds to the accumulated number of traps over the life of the command. By default, trapstat displays data once per second, and runs indefi- nitely; this behavior can be optionally controlled with the -r option or the interval and count parameters. The -r option argument specifies the rate in times per second to sample and display data. The interval is specified in seconds; the count indicates the number of intervals to be executed before exiting. Alternatively, command can be specified, in which case trapstat executes the provided command and continues to run until the command exits, then diplays the accumulated data. A positive integer is assumed to be an interval; if the desired command cannot be distinguished from an integer, the full path of command must be speci- fied. Only one of -r, interval or command may be used. UltraSPARC systems may handle translation lookaside buffer (TLB) misses by trapping to the operating system. TLB miss traps can be a signifi- cant component of overall system performance for some workloads; the -t option provides in-depth information on these traps. When run with this option, trapstat displays both the rate of TLB miss traps and the per- centage 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 UltraSPARC II User's Manual.) The TLB and TSB miss information is further broken down into user- and kernel-mode misses. Workloads with working sets that exceed the TLB reach may spend a sig- nificant amount of time missing in the TLB. To accommodate such work- loads, 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, trapstat optionally provides in-depth TLB miss information broken down by page size using the -T option. The informa- tion provided by the -T option is a superset of that provided by the -t option; only one of -t and -T can be specified. OPTIONS The following options are supported: -a Displays the number of traps as accumulating, monotonically increasing values instead of per-second or per-interval rates. -A cor Aggregate output by core ID. Data rows having the same core ID are aggregated into one row. The columns are replaced with subtotals, by default. The -m option prints column averages, instead. -A soc Aggregate output by socket ID. Data rows having the same socket ID are aggregated into one row. The columns are replaced with subto- tals, by default. The -m option prints column averages, instead. -A bins Aggregate the columns into a lesser number of bins within each sam- pling period, grouping them in the order in which they appear. The -m option may be used in order to compute the arithmetic mean instead of the subtotal. The -k sorting option may be used to change the column order prior to the binning step. Aggregation by ID (-A cor|soc) is processed before sorting (-k). Grouping by bins (-A bins) is done next. Finally, the number of output lines printed per interval may be limited by -o. -c cpulist Enables trapstat only on the CPUs specified by cpulist. cpulist can be a single processor ID (for example, 4), a range of processor IDs (for example, 4-6), or a comma separated list of pro- cessor IDs or processor ID ranges (for example, 4,5,6 or 4,6-8). -C processor_set_id Enables trapstat only on the CPUs in the processor set specified by processor_set_id. trapstat modifies its output to always reflect the CPUs in the specified processor set. If a CPU is added to the set, trapstat modifies its output to include the added CPU; if a CPU is removed from the set, trapstat modifies its output to exclude the removed CPU. At most one processor set can be specified. -e entrylist Enables trapstat only for the trap table entry or entries specified by entrylist. A trap table entry can be specified by trap number or by trap name (for example, the level-10 trap can be specified as 74, 0x4A, 0x4a, or level-10). entrylist 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, trapstat prints a table of all valid trap table entries by name and value. A list of valid trap table entries is also found in The SPARC Architecture Manual, Version 9 and the Sun Microelec- tronics UltraSPARC II User's Manual. If the parsable option (-P) is specified in addition to the -e option, the format of the data is as specified under the description of the -P option: -I statfile Replay data previously saved in statfile. Create data files for replay by specifying -O. This option is especially useful for ana- lyzing statistics on machines with large numbers of CPUs. The file may be reprocessed multiple times using different sorting and aggregation options. In order to help interpret the data, the original command used to gather the data is displayed at the top of the output, unless -P is specified. The -I option is incompatible with the -O, -T, -t, -e, -c, -C, -a and -r options. It cannot be used with an interval and count speci- fication or a command parameter. -k key1,... Sort rows within each sampling period from highest to lowest by key1, then key2, and so on. Each key may be any of the row headers in the trapstat output, such as level-10, u-itlb-miss, and so forth. Use trapstat -l to list all event names. Use -lt or -lT to list key names for the TLB formats. Use -l with -P for parsable lists. -l Lists trap table entries. By default, a table is displayed contain- ing all valid trap numbers, their names and a brief description. The trap name is used in both the default output and in the entrylist parameter for the -e argument. If the parsable option (-P) is specified in addition to the -l option, the format of the data is as follows: Field Contents 1 Trap number in hexadecimal 2 Trap number in decimal 3 Trap name Remaining Trap description The first three fields are separated with whitespace. The last field may contain whitespaces. If the format is modified it will be compatible with the existing fields. See the -k, -t and -T options for other uses of -l. -m Display the arithmetic mean value rather than the sum when the -A option is used to aggregate data over multiple CPUs. -o num Display only the first num rows within each sampling period, after applying any sorting and aggregation options. -O statfile Save gathered data to statfile. This data may be replayed at a later time using -I. Write to the standard output if the file name is -- (hyphen). The purpose of -O is to capture all the specified data. It is incompatible with the data reduction options: -A, -k, -m, and -o. Since the statfile format is fixed, the -P option cannot be used with -O. -P Generates parsable output. When run without other data gathering modifying options (that is, -t or -T) or with -e, trapstat's parsable output has the following format: Field Contents 1 Timestamp (nanoseconds since start) 2 CPU/core/socket/bin ID 3 Trap number (in hexadecimal) 4 Trap name 5 Trap rate per interval 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. -r rate Explicitly sets the sampling rate to be rate samples per second. If this option is specified, trapstat's output changes from a traps- per-second to traps-per-sampling-interval. Cannot be used with com- mand or interval parameters. -t Enables TLB/TSB statistics. A table is displayed with four principal columns of data: itlb- miss, itsb-miss, dtlb-miss, and dtsb-miss. The columns contain both the rate of the corresponding event and the percentage of CPU time spent processing the event. The rows of the table correspond to CPUs, (or cores, sockets or bins, if -A was specified), with each one consuming two rows: one row for: one row for user-mode events (denoted with u) and one row for kernel-mode events (denoted with k). For each row, the percentage of CPU time is totalled and dis- played in the rightmost column. The CPUs are delineated with a solid line. If the parsable option (-P) is specified in addition to the -t option, the format of the data is as follows: Field Contents 1 Timestamp (nanoseconds since start) 2 CPU/core/socket/bin ID 3 Mode (k denotes kernel, u 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 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. -T Enables TLB/TSB statistics, with page size information. As with the -t option, a table is displayed with four principal columns of data: itlb-miss, itsb-miss, dtlb-miss, and dtsb-miss. The columns contain both the absolute number of the corresponding event, and the percentage of CPU time spent processing the event. The rows of the table correspond to CPUs (or cores, sockets or bins if -A was specified), with each CPU consuming two sets of rows: one set for user-level events (denoted with u) and one set for kernel-level events (denoted with k). Each set, in turn, contains as many rows as there are page sizes supported (see getpagesizes(3C)). For each row, the percentage of CPU 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 (-P) is specified in addition to the -T option, the format of the data is as follows: Field Contents 1 Timestamp (nanoseconds since start) 2 CPU/core/socket/bin ID 3 Mode k denotes kernel, u 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 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. EXAMPLES Example 1 Using trapstat Without Options When run without options, trapstat 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 dis- played: example# trapstat 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 Example 2 Using trapset with CPU Filtering The -c option can be used to limit the CPUs on which trapstat is enabled. This example limits CPU 1 and CPUs 12 through 15. example# trapstat -c 1,12-15 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 Example 3 Using trapstat with TLB Statistics The -t option displays in-depth TLB statistics, including the amount of time spent performing TLB miss processing. The following example shows that the machine is spending 14.1 percent of its time just handling D- TLB misses: example# trapstat -t 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 Example 4 Using trapstat with TLB Statistics and Page Size Information By specifying the -T option, trapstat shows TLB 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. example# trapstat -T -c 0 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 Example 5 Using trapstat with Entry Filtering By specifying the -e option, trapstat displays statistics for only spe- cific trap types. Using this option minimizes the probe effect when seeking specific data. This example yields statistics for only the dtlb-prot and syscall-32 traps on CPUs 12 through 15: example# trapstat -e dtlb-prot,syscall-32 -c 12-15 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 Example 6 Using trapstat with a Higher Sampling Rate The following example uses the -r option to specify a sampling rate of 1000 samples per second, and filter only for the level-10 trap. Addi- tionally, specifying the -P option yields parsable output. Notice the timestamp difference between the level-10 events: 9,998,000 nanoseconds and 10,007,000 nanoseconds. These level-10 events corre- spond to the system clock, which by default ticks at 100 hertz (that is, every 10,000,000 nanoseconds). example# trapstat -e level-10 -P -r 1000 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 Example 7 Display Three CPUs with Highest cpu_mondo Rate The following command displays the three CPUs with the highest cpu_mondo rate. example% trapstat -k cpu_mondo -o 3 10 1 vct name | cpu0 cpu1 cpu61 ------------------------+---------------- 9 immu-miss | 0 0 0 24 cleanwin | 0 0 0 31 dmmu-miss | 0 0 0 41 level-1 | 0 0 0 46 level-6 | 0 0 0 49 level-9 | 0 0 0 4a level-10 | 100 31 16 4d level-13 | 23 15 8 4e level-14 | 100 32 18 6c dtlb-prot | 0 0 0 7c cpu_mondo | 24 16 9 7d dev_mondo | 0 0 0 84 spill-user-32 | 0 0 0 8c spill-user-32-cln | 0 0 0 98 spill-kern-64 | 423 180 102 a4 spill-asuser-32 | 0 0 0 ac spill-asuser-32-cln | 0 0 0 c4 fill-user-32 | 0 0 0 cc fill-user-32-cln | 0 1 0 d8 fill-kern-64 | 295 165 94 103 flush-wins | 0 0 0 108 syscall-32 | 0 0 0 122 get-psr | 0 0 0 127 gethrtime | 0 0 0 Example 8 Aggregating Multiple CPUs into Quartiles The following commands aggregate 96 CPUs into quartiles by level-10 rate. example% trapstat -O /tmp/t1 -e level-10 10 1 example% trapstat -I /tmp/t1 -A 4 replay from: trapstat -O /tmp/t1 -e level-10 10 1 vct name | bin0 bin1 bin2 bin3 -------------+-------------------- 4a level-10 | 440 340 305 306 Example 9 Aggregating and Sorting Multiple CPUs The following command aggregates 96 CPUs by core ID and sorts for the highest four. example% trapstat -A cor -e level-10 -k level-10 -o 4 10 1 vct name | cor514 cor549 cor542 cor521 -------------+-------------------------------- 4a level-10 | 197 120 111 106 ATTRIBUTES See attributes(5) for descriptions of the following attributes: +-----------------------------------------------------------+ | ATTRIBUTE TYPE ATTRIBUTE VALUE | |Availability system/core-os | |Interface Stability | | Human Readable Output Uncommitted | | Parsable Output Committed | +-----------------------------------------------------------+ SEE ALSO lockstat(1M), pmap(1), psrset(1M), psrinfo(1M), pbind(1M), ppgsz(1), getpagesizes(3C) Sun Microelectronics UltraSPARC II User's Manual, January 1997, STP1031, The SPARC Architecture Manual, Version 9, 1994, Prentice-Hall. NOTES When enabled, trapstat 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: Option Approximate probe effect default 3-5% per trap -e 3-5% per specified trap -t, -T 40-45% per TLB miss trap hitting in the TSB, 25-30% per TLB miss trap missing in the TSB These probe effects are per trap not for the system as a whole. For example, running trapstat with the default options on a system that spends 7% of total time handling traps induces a performance degrada- tion of less than one half of one percent; running trapstat with the -t or -T option on a system spending 5% of total time processing TLB misses induce a performance degradation of no more than 2.5%. When run with the -t or -T option, trapstat accounts for its probe effect when calculating the %tim fields. This assures that the %tim fields are a reasonably accurate indicator of the time a given workload is spending handling TLB misses -- regardless of the perturbing pres- ence of trapstat. While the %tim fields include the explicit cost of executing the TLB miss handler, they do not 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 %tim val- ues 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. Due to the potential system wide degradation induced, only the super- user can run trapstat. Due to the limitation of the underlying statistics gathering methodol- ogy, only one instance of trapstat can run at a time. UltraSPARC sun4v platforms with hardware support for handling TLB misses (for example, Hardware Table Walk or HWTW) will mask TLB misses from the operating system. Trapstat normally disables HWTW through the hypervisor when it is enabled. Due to the potentially large performance degradation this can cauase, sun4v platforms provide an alternate, "fast" method for gathering TLB miss data. Currently, only UltraSPARC T1 based system fully implement this functionality: on other sun4v sys- tems, the TLB miss data gathered by trapstat will always be 0. SunOS 5.11 24 Feb 2014 trapstat(1M)
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