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Text File | 1990-07-30 | 18.4 KB | 465 lines

VMSTAT User Commands VMSTAT _________________________________________________________________ NNAAMMEE vmstat - print virtual memory stats SSYYNNOOPPSSIISS vvmmssttaatt [--ssvvmmPP] [--tt _i_n_t_e_r_v_a_l] [--TT _m_a_x_S_k_i_p] [--ll _l_i_n_e_s] [--ffpp _t_h_r_e_s_h_o_l_d] OOPPTTIIOONNSS --ss Print out statistics about all in-use segments instead of overall vm stats. --vv Print out extra information when printing overall vm stats. --tt _i_n_t_e_r_v_a_l Print out a line of terse vm stats every _i_n_t_e_r_v_a_l seconds. If _i_n_t_e_r_v_a_l is specified as 0 then only a single line is printed. --mm Print out the number of modified pages instead of kernel stack pages when using the --tt option. --ll _n_u_m_L_i_n_e_s Print out _n_u_m_L_i_n_e_s lines before printing the header again when using the --tt option. The default is 25 lines. --ff _t_h_r_e_s_h_o_l_d Number of page faults per second before should print out stats with the --tt option. No lines will be printed unless more than _t_h_r_e_s_h_o_l_d page faults occur or the --pp or --TT options are in effect. --pp _t_h_r_e_s_h_o_l_d Number of page-outs per second before should print out stats with the --tt option. No lines will be printed unless more than _t_h_r_e_s_h_o_l_d page-outs occur or the --ff or --TT options are in effect. --TT _m_a_x_S_k_i_p Maximum number of times to skip printing out statistics because of the --ff and --pp options. --PP Print out statistics since the last time that they were printed, not since the last inter- val. Used with the --tt option. _________________________________________________________________ DDEESSCCRRIIPPTTIIOONN This command prints out virtual memory statistics. There are three possible formats and types of information that are printed. The default is to print overall virtual memory Sprite v.1.0 Printed: July 30, 1990 1 VMSTAT User Commands VMSTAT statistics; the volume of statistics that are printed is controlled by the --vv option. If the --ss option is specified then statistics about all actively used segments are printed instead. If the --tt option is specified then a terse line of information is printed at regular intervals; the --TTllffppPPmm options control how the data is formatted and how often it is printed. The next three sections describe the three printing formats in more detail. GGEENNEERRAALL SSTTAATTIISSTTIICCSS By default vvmmssttaatt prints out general statistics about the virtual memory system. If the --vv option is specified then more detailed statistics will be printed. The normal infor- mation that is printed is divided into 5 sections: memory use, segment use, page fault statistics, page-out statistics and copy-on-write activity. The memory use section is titled ``MEMORY STATS'' and contains 6 lines of information with the following titles and information: _P_a_g_e _S_i_z_e The logical page size; this is a multiple of the physical page size. _M_e_m_o_r_y _S_i_z_e The amount of physical memory in Kbytes that is available on the machine. _K_e_r_n_e_l _M_e_m_o_r_y The amount of memory in Kbytes that is being used by the kernel. There are four pieces of information on this line (from left to right): the total amount of memory used by the kernel, the portion of the total that is used for kernel code and data, the portion used for kernel stacks and the portion that is kept in emergency reserve. _U_s_e_r _M_e_m_o_r_y The amount of memory in Kbytes that is being used by user processes. There are 3 pieces of information on this line (from left to right): the total amount of memory used by user processes, the portion of the total that is dirty and the portion that is clean. _F_S _M_e_m_o_r_y The amount of memory in Kbytes that is being used by the file system. The 3 pieces of information on this line are (from left to right): the total amount of memory used by the file system, the minimum amount of memory that has ever been used and the maximum amount that has been used. _F_r_e_e _M_e_m_o_r_y The amount of memory in Kbytes that is not being used by anyone. Sprite v.1.0 Printed: July 30, 1990 2 VMSTAT User Commands VMSTAT The second section of statistics is entitled ``SEGMENT STATS''. This section contains four lines of information, one each for active code segments, inactive code segments, heap segments and stack segments. Each contains the number of segments of the given type and the amount of memory in Kbytes that is being used by the particular type of segment. The third section of statistics is entitled ``FAULT STATS''. The first line contains the total number of faults. The second line divides the total faults into the 7 different types of faults: _Z_e_r_o Pages that are filled with zeroes. _F_S Pages that are filled from an object file in the file system. _S_w_a_p Pages that are filled from a swap file. _Q_u_i_c_k Page faults that were handled merely by validating the page in hardware. _C_O_W Copy-on-write faults. _C_O_R Copy-on-reference faults. _C_O_R-_m_o_d Faults that occured because pages that were filled because of copy-on-reference faults were marked as read-only. This is done to compare copy-on- reference to copy-on-write (see _v_m_c_m_d for details). The third line divides the faults into the different seg- ments that the faults occured in. The last line is the number of faults that collided with another process faulting on the same page. The fourth section which is entitled ``PAGE-OUTS'' contains the number of pages that were written to swap space. The last section is entitled ``COPY-ON-WRITE'' and contains statistics about copy-on-write and copy-on-reference behavior. The information in this section is presented as the number of faults that occured divided by the number of copy-on-write or copy-on-reference pages. Statistics are presented for both heap and stack segments separately (the entries are labeled _H_e_a_p and _S_t_a_c_k respectively) and for the sum of the heap and stack statistics (labeled _T_o_t). The first two lines contain information about copy-on-write (COW) behavior, the second two about copy-on-reference (COR) behavior and the last two about the percentage of pages that were copied because of copy-on-reference faults that were Sprite v.1.0 Printed: July 30, 1990 3 VMSTAT User Commands VMSTAT eventually modified (COR-mod). The information about COW behavior contains an additional statistic labeled _Q_u_i_c_k which is the number of copy-on-write faults that were han- dled by merely changing the protection; no copy was required. When the --vv option is specified additional results are presented. These results are more obscure and are probably only of interest to those who understand the internals of the Sprite virtual memory system. The first additional statistic is a measurement of the need for modify bits and is given under the ``MEMORY STATS'' section. This line of statistics which is labeled _M_o_d _p_a_g_e _s_t_a_t_s gives three bits of information. The first entry (labeled _P_o_t-_m_o_d) is the number of page frames that were being actively used by heap and stack segments that were taken away from the segment and given to another segment; since these segments are writable, the pages in these segments are potentially modified. The second entry (labeled _N_o_t-_m_o_d) is the number of potentially modified pages that were clean. The last entry (labeled _N_o_t-_h_a_r_d-_m_o_d) is the number of potentially modified pages that did not have the hardware modify bit set; pages can be marked as modified by the virtual memory system (e.g. zero- filled pages) even though they do not have the modify bit set by the hardware. The second extra set of statistics is under the ``PAGE- OUTS'' section. The first extra line which is labeled _C_l_e_a_n-_w_a_i_t is the number of times that processes that were exiting had to wait because a page that they were freeing was being cleaned. The second line labeled _C_l_e_a_n_e_r _s_t_a_r_t_s is the number of times that a page cleaner was started up to write out pages. The remaining extra statistics that are printed with the --vv option are under entirely different sections. The first section which is entitled ``ALLOCATION STATS'' gives statis- tics about the allocation of memory. The first line which is labeled _V_m _a_l_l_o_c_s gives the following information (from left to right): the total number of pages that were allo- cated, the portion of this total that came from the free list, the portion that came from the file system and the portion that came from the allocate list. The second line which is labeled _V_M-_F_S _s_t_a_t_s gives statistics about the vir- tual memory and file system negotiation. The first two entries give the number of times that the file system asked the virtual memory system for the age of its oldest page (labeled _F_S-_a_s_k_e_d) and the number of these times that a free page was available (labeled _H_a_d-_f_r_e_e-_p_a_g_e). The second two entries give the number of pages that the file system added to its cache and the number of pages that it deleted from its cache (labeled _F_S-_m_a_p and _F_S-_u_n_m_a_p respectively). Sprite v.1.0 Printed: July 30, 1990 4 VMSTAT User Commands VMSTAT The next two lines of statistics under the ``ALLOCATION STATS'' section contains information about searching the memory lists. The first line gives how many times that the lists were searched for pages and how many times the memory was found on the free list and how many times it was found on the allocation list (labeled _F_r_e_e and _I_n-_u_s_e respec- tively). The second line gives information about why multi- ple iterations through the allocation list were required; most of the time the first element on the list can be used. This line contains the following information from left to right: the total number of extra searches, the portion of extra searches that were required because the page frame was locked (labeled _L_o_c_k), the page frame was referenced (_l_a_b_e_l_e_d _R_e_f) or the page frame was dirty (_D_i_r_t_y). The next section of statistics is entitled ``LIST STATS''. This section gives the current number of pages that are on each of the four memory list. The next section is labeled ``PAGE MAPPING STATS''. This section gives the number of times a process had to wait because the fixed number of slots that are used to map user pages into the kernel's virtual address spacce were all in use. The last section is entitled ``HARDWARE STATS'' and contains information that depends on the hardware. For Sun worksta- tions it contains statistics about many times one of the 8 hardware contexts had to be taken away from one process and given to another and the number of times that a hardware PMEG had to be taken away from one segment and given to another. For MIPS R2000/R3000 based machines such as DecSta- tions, the number of times TLB pids were stolen from active processes is reported. SSEEGGMMEENNTT SSTTAATTIISSTTIICCSS When the -_s option is given to vvmmssttaatt then statistics about all in use segments are printed. There are 6 columns of information: _S_E_G-_N_U_M The segment number. _T_Y_P_E The type of segment. The segment type can be _I_n_a_c_t_i_v_e for inactive code seg- ments or _C_o_d_e, _H_e_a_p or _S_t_a_c_k for the other three types of segments. _S_I_Z_E The total size of the segment's virtual addres space in Kbytes. _R_E_S-_S_I_Z_E The amount of physical memory occupied by the segment in Kbytes. Sprite v.1.0 Printed: July 30, 1990 5 VMSTAT User Commands VMSTAT _N_U_M-_R_E_F_S The number of processes that are actively using this segment. _O_B_J_E_C_T-_F_I_L_E-_N_A_M_E The name of the object file that the code segment is being demand loaded from. After the information about each individual segment is printed a summary of the segment information is printed. SSTTAATTIISSTTIICCSS AATT RREEGGUULLAARR IINNTTEERRVVAALLSS If the --tt _i_n_t_e_r_v_a_l option is given to vvmmssttaatt then a line of terse statistics is printed out at regular intervals. If _i_n_t_e_r_v_a_l is 0 then only a single line of statistics is printed. If _i_n_t_e_r_v_a_l is greater than 0 then a line of statistics is printed out every _i_n_t_e_r_v_a_l seconds. If the --ff _f_a_u_l_t_T_h_r_e_s_h_o_l_d and/or --pp _p_a_g_e_o_u_t_T_h_r_e_s_h_o_l_d options are used then statistics will be checked every _i_n_t_e_r_v_a_l seconds but only will be printed out if the number of page faults in the last interval is greater than _f_a_u_l_t_T_h_r_e_s_h_o_l_d or the number of pageouts is greater than _p_a_g_e_o_u_t_T_h_r_e_s_h_o_l_d. If the --TT _m_a_x_S_k_i_p option is used then statistics will be printed out at least every _m_a_x_S_k_i_p intervals regardless whether or not enough page-outs or page faults have occured. All memory use statistics are printed in units of 1024 bytes. Each line contains 10 columns of information: _A_V_A_I_L The total amount of physical memory available. _F_R_E_E The amount of memory that is not being used by anyone. _U_S_E_R The amount of memory that is being used by user processes. _K_M_E_M The amount of memory that is being used by the kernel for code and data. _K_S_T_K The amount of memory that is being used for kernel stacks. _F_S$ The size of the file system cache. _P_F-_N_U_M The number of page faults that have occured. _P_F-_S_W_P The number of page faults that were filled from swap space. _P_F-_F_S The number of page faults that were filled from the file system. Sprite v.1.0 Printed: July 30, 1990 6 VMSTAT User Commands VMSTAT _P_O_U_T_S The number of pages that were written to swap space. If the --mm option is specified then the _K_S_T_K column will be replaced by a column labeled _M_O_D% which contains the percen- tage of user memory that is modified. The number of kernel stack pages will be added into the statistics under the _K_M_E_M column. By default a new column header line will be printed after 25 lines of output. The --ll _l_i_n_e_s option can be used to force the header line to be printed after _l_i_n_e_s lines of output are printed. The number of page faults and page-outs that are printed are by default the number since the last interval. However, many intervals can be skipped because of the --ff and --pp options. The --PP option will force vvmmssttaatt to print out the number of faults and pageouts since the last time that a line was printed instead of since the last interval. KKEEYYWWOORRDDSS virtual memory, statistics Sprite v.1.0 Printed: July 30, 1990 7