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  • Cycles/byte calculations

    - by matskn
    Hi ! In Crypto communities it is common to measure algorithm performance in cycles/byte. My question is, which parameters in the CPU architecture are affecting this number? Except the clockspeed ofcourse :)

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  • JVM cannot use 8 CPUon Linux

    - by Trustin
    I have observed that JVM cannot user 8 CPU advantage. Because when a thread runs more than 1 secs, other threds are waiting for it. there is no lock beetween these threds is there any jvm option for this ?

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  • Can Acrobat 11 be made to do OCR using multiple CPU cores?

    - by tarcman.
    OCR processing takes time. Using multiple CPU cores would speed up processing. Acrobat 10 was not a multithreaded application. How about Acrobat 11? Does 11 by default do OCR using multiple CPU cores (if available)? If not, are there any workarounds, e.g. scripting, to help make Acrobat 11 do OCR using multiple CPU cores? Either through Acrobat's built in scripting language or using external scripts that launch and direct multiple single thread instances of Acrobat to in parallell to parts of the processing job. Note: This question is not too localized (not limited to a specific moment in time) because (1) Adobe does not release new major Acrobat versions very often (Acrobat 10 was released two years ago) and (2) Adobe Acrobat is a widely used application.

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  • How can I judge the suitability of modern processors for systems with specific CPU requirements?

    - by Iszi
    Inspired by this question: How do I calculate clock speed in multi-core processors? The answers in the above question do a fair job of explaining why a lower-speed multi-core processor won't necessarily perform at the same level as a higher-speed single-core processor. Example: 4*2=8, but a quad-core 2 GHz processor isn't necessarily as fast as a single-core 8 GHz processor. However, I'm having a hard time putting the information in those answers to practical use in my mind. Particularly, I want to know how it should be used to judge whether a given CPU is appropriate for an application with specific requirements. Example scenarios: An application has a minimum CPU requirement of 2.4 GHz dual-core. Another application has a minimum CPU requirement of 1.8 GHz single-core. For either of the above scenarios: Would a higher-speed processor with fewer cores, or a lower-speed processor with more cores, be equally sufficient? If so, how can we determine the appropriate processor speeds required for a given number of cores?

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  • Why does my CPU Usage reach 100% too often?

    - by deathlock
    I'm using a dual-core processor and often see my CPU usage reaches 100%. I realize this may happen if I'm running too much applications, so when I know the computer starts to run slowly, I start to close my applications. I usually run 4-5 applications simultaneously. Usually those are: web browser (Google Chrome), Adobe Photoshop, Notepad++, XAMPP, and Windows Task Manager. Usually I close tabs in my Chrome first, because I often browse the net with about 20 tabs/4 windows open, so I presume that would take much memory (bad habit, I know). But even after closing Chrome's tabs or closing other applications, my CPU Usage often stays at high percentage - 72% at best, 100% at worst. I check the Processes tab on Windows Task Manager and usually found the System, System Idle Process, or services.exe taking the highest CPU process (could reach 60). Why is this happening? And is there any solution? EDIT I have T2250 @ 1,73 Ghz and 2.5 GB RAM

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  • What is normal SCSI error handling process (scsi_eh_3) CPU time usage?

    - by Kris Jordan
    Last week I got setup with a new dedicated server that is running 4x SCSI drives in RAID 10 on CentOS. The machine is pretty lightly loaded at the moment and has been running for 8 days. The process 'scsi_eh_3' has a CPU time of 13:09.67 in top. This is 3x the next closest CPU time of 4:03.93 for mysqld. Is it normal for the scsi error handling process to use this much CPU time? (Seems like it goes to 0.3% usage ever 5 seconds.) Could this be an indicator that one or more of the drives is having issues?

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  • What service can hold CPU at lowest frequency possible when on battery load under Ubuntu?

    - by vava
    When I'm running on battery even with "performance" frequency scaling governor, something regularly lowers CPU speed to it's lowest value. I don't really want that, my AC strip usually in another room so I don't really need to save power. How can I find what service doing that? laptop_mode is disabled so that's not it. Update: Looks like CPU being scaled down only if it is under load. If it is more or less idle, it could stay on any frequency pretty much forever, but once it gets loaded, it quickly jumps to it's lowest frequency. Another update: Something sets maximum frequency CPU can have. Ubuntu launchpad bug 242006

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  • EC2 Amazon Linux AMI MySQL CPU @ 62% When Idle?

    - by Jeff
    I am running MySQL on an Amazon Linux AMI. There is nothing connected to it. There are no connections and no other applications running that use MySQL. It is completely idle, but yet, top is reporting that mysql is using 62% of the CPU? Why is this happening and how do I fix it? Cpu(s): 0.2%us, 0.2%sy, 0.0%ni, 97.8%id, 0.0%wa, 0.0%hi, 0.0%si, 1.7%st Mem: 1738504k total, 390708k used, 1347796k free, 56888k buffers Swap: 917500k total, 0k used, 917500k free, 229804k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 2959 mysql 20 0 466m 39m 5244 S 62.2 2.3 4:00.67 mysqld 1 root 20 0 19252 1504 1212 S 0.0 0.1 0:00.20 init 2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd There are no connections... mysql> show processlist; +----+------+-----------+------+---------+------+-------+------------------+ | Id | User | Host | db | Command | Time | State | Info | +----+------+-----------+------+---------+------+-------+------------------+ | 5 | root | localhost | NULL | Query | 0 | NULL | show processlist | +----+------+-----------+------+---------+------+-------+------------------+

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  • Any way to disable specific CPU idle (Cx) states?

    - by Philippe
    I just got a new Toshiba Tecra S11 notebook, which has a Core i5 520M CPU, and it appears to suffer from a well-known problem: a high pitched noise when the CPU is idle. Googling around revealed that this is caused by a specific power-saving mode in the CPU. In most cases, C4 mode is blamed for the noise. So my question is: is it possible to disable C4 mode (or any other "sleep" mode) using some utility or BIOS setting? I don't mind if it hurts battery life. I'd appreciate any advice on this matter. It's driving me crazy. FYI: I'm running Windows 7 64-bit

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  • Vim: How to handle newlines when storing multiple commands in registers?

    - by UncleZeiv
    I have a file where I store snippets of vim commands. When I need a snippet, I yank it and then execute it with @". The snippets are stored as a script, one line per command, like this: :s/foo/bar/g :echo "hello" :s/1/2/g Edit: I removed normal mode commands from the example, as they were not part of the problem. Now this procedure doesn't work anymore: when executing the snippet, it just stops at the first line as if waiting for a newline. Is there an option somewhere affecting how @ is executed? I'm pretty sure it was working some time ago... Substituting the newline with a ^M character works but makes the file more difficult to handle. Additional information: Here's another symptom: when I yank a snippet, if I execute it with @" it stops at the first line as I just explained. But if I execute it with :@ it works. But the help file doesn't seem to imply any difference in how the two commands treat the register's content...

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  • Solaris ????????????????

    - by Homma
    ???? ???????????? CPU ?????????????????????????????????? OS ??????????????????????????????????????????????CPU ??????????????????? CPU ???????????????????????????????????????????????????????????????????????????? CPU ??????????????????????????????????? CPU ???????????????????????? CPU ????????????????????????? CPU ?????????????????????????????????????????????????????????????????????????????DTrace ????????????????? ?? ????????????????????????????????????????????? CPU ????????????????? # cat prog01.c int main() { while(1) {}; } # gcc prog01.c -o prog01 ?????????????????????pbind ?????????? CPU 1 ??????psradm ????????? CPU 1 ?????????????????????????? CPU 1 ?????????????? # ./prog01 & [1] 3247 # pbind -b 1 3247 process id 3247: was not bound, now 1 # psradm -i 1 # psrinfo 1 1 no-intr since 09/24/2012 05:46:25 ????????? Solaris 10 8/11 ????????? # cat /etc/release Oracle Solaris 10 8/11 s10x_u10wos_17b X86 Copyright (c) 1983, 2011, Oracle and/or its affiliates. All rights reserved. Assembled 23 August 2011 ????????????????????????? DTrace ??????????????(??????)???????????????????????????? preempt ??????????????????? DTrace ????????????????????????????????????????????????????????????????????????????? # dtrace -qn 'BEGIN{ ts = timestamp; } sched:::preempt/pid == $target/ { printf("%d\n",timestamp - ts); ts = timestamp }' -p 3247 ?????????????????????? 200 ????????????????????? # dtrace -qn 'BEGIN{ ts = timestamp; } sched:::preempt/pid == $target/ { printf("%d\n",timestamp - ts); ts = timestamp }' -p 3247 3547836 199976558 200030610 199964001 200001048 199999666 200021432 ???????????? 200 ????? CPU ????????????? CPU ????????????????????? ??????? CPU 1 ????????????? prog01 ?????????????????????????????????? prog01 ?????????????????????????????????????????????????????????? 200 ??????????????? ????????????????????????? ?????????????????????????????? DTrace ????????DTrace ???????????????????????????????????????????????????????????????????? # dtrace -qn 'sched:::preempt/pid == $target/ { printf("%d\n", ((tsproc_t*)curthread->t_cldata)->ts_timeleft); }' -p 3247 ??????????????????????????????? 1/100 ???????? 200 ????????????????? # dtrace -qn 'sched:::preempt/pid == $target/ { printf("%d\n", ((tsproc_t*)curthread->t_cldata)->ts_timeleft); }' -p 3247 20 20 20 20 20 20 ????????? 200 ???????????????????? ???????? 200 ??????????????????????????????????????????????????????????????????????????????? DTrace ???????DTrace ??????????????? # dtrace -qn 'sched:::preempt/pid == $target/ { printf("%d\n", ((tsproc_t*)curthread->t_cldata)->ts_cpupri); }' -p 3247 ???????????????????????????? # dtrace -qn 'sched:::preempt/pid == $target/ { printf("%d\n", ((tsproc_t*)curthread->t_cldata)->ts_cpupri); }' -p 3247 0 0 0 0 0 0 ????????????????? 0 ???????? 0 ?????????????????????? dispadmin ???????????????? # dispadmin -c TS -g | head # Time Sharing Dispatcher Configuration RES=1000 # ts_quantum ts_tqexp ts_slpret ts_maxwait ts_lwait PRIORITY LEVEL 200 0 50 0 50 # 0 200 0 50 0 50 # 1 200 0 50 0 50 # 2 200 0 50 0 50 # 3 200 0 50 0 50 # 4 200 0 50 0 50 # 5 ???????PRIORITY LEVEL 0 ???????? ts_quantum ? 200 ??????????? 0 ???? 200 ???????????????????????????(RES ??? 1000 ????ts_quantum ???? 1/1000 ?)? ????????? ????????????????????? mpstat ????????????????????????????icsw ??? 5 ???????????200 ?????????????????????????????????????????????????????? CPU ??? 200 ????????????? # mpstat 1 | egrep '^ 1|csw' CPU minf mjf xcal intr ithr csw icsw migr smtx srw syscl usr sys wt idl 1 0 0 347 196 1 42 1 3 0 0 2 9 1 0 90 CPU minf mjf xcal intr ithr csw icsw migr smtx srw syscl usr sys wt idl 1 0 0 0 16 0 0 5 0 0 0 0 100 0 0 0 CPU minf mjf xcal intr ithr csw icsw migr smtx srw syscl usr sys wt idl 1 0 0 0 7 0 0 5 0 0 0 0 100 0 0 0 CPU minf mjf xcal intr ithr csw icsw migr smtx srw syscl usr sys wt idl 1 0 0 0 8 0 0 5 0 0 0 0 100 0 0 0 CPU minf mjf xcal intr ithr csw icsw migr smtx srw syscl usr sys wt idl 1 0 0 0 18 1 0 5 0 0 0 0 100 0 0 0 ???????????? Solaris ????????????????????????????????????????????? priocntl ???????????????? 1 ?????????? # priocntl -s -c FX -t 1000 -i pid `pgrep prog01` ??????? mpstat ?????????CPU ??????? 1 ?????????????????????????????????????????????????????????????????????????????????????????????????????????????? # mpstat 1 | egrep '^ 1|csw' CPU minf mjf xcal intr ithr csw icsw migr smtx srw syscl usr sys wt idl 1 0 0 346 196 1 42 1 3 0 0 2 9 1 0 90 CPU minf mjf xcal intr ithr csw icsw migr smtx srw syscl usr sys wt idl 1 0 0 0 2 0 0 1 0 0 0 0 100 0 0 0 CPU minf mjf xcal intr ithr csw icsw migr smtx srw syscl usr sys wt idl 1 0 0 0 2 0 0 1 0 0 0 0 100 0 0 0 CPU minf mjf xcal intr ithr csw icsw migr smtx srw syscl usr sys wt idl 1 0 0 0 13 0 0 2 0 0 0 0 100 0 0 0 CPU minf mjf xcal intr ithr csw icsw migr smtx srw syscl usr sys wt idl 1 0 0 0 2 0 0 1 0 0 0 0 100 0 0 0 CPU minf mjf xcal intr ithr csw icsw migr smtx srw syscl usr sys wt idl 1 0 0 0 5 1 0 1 0 0 0 0 100 0 0 0 ????DTrace ????????????????????????????? # dtrace -qn 'sched:::preempt/pid == $target/ { printf("%d\n", ((fxproc_t*)curthread->t_cldata)->fx_timeleft); }' -p `pgrep prog01` 100 100 100 100 100 100 ??? Solaris ???????????????????????????????????????????????????????????????? 200 ???????????????????????????????????????????????? ??????????????????????????????????????????????????????????????? CPU ?????????I/O ?????????????????????????????????????????????????????????? ?????????????????????????? http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/uts/common/disp/ ????????? ???????????????????

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  • AMD FX8350 CPU - CoolerMaster Silencio 650 Case - New Water Cooling System

    - by fat_mike
    Lately after a use of 6 months of my AMD FX8350 CPU I'm experiencing high temperatures and loud noise coming from the CPU fan(I set that in order to keep it cooler). I decided to replace the stock fan with a water cooling system in order to keep my CPU quite and cool and add one or two more case fans too. Here is my case's airflow diagram: http://www.coolermaster.com/microsite/silencio_650/Airflow.html My configuration now is: 2x120mm intake front(stock with case) 1x120mm exhaust rear(stock with case) 1 CPU stock I'm planning to buy Corsair Hydro Series H100i(www.corsair.com/en-us/hydro-series-h100i-extreme-performance-liquid-cpu-cooler) and place the radiator in the front of my case(intake) and add an 120mm bottom intake and/or an 140mm top exhaust fan. My CPU lies near the top of the MO. Is it a good practice to have a water-cooling system that takes air in? As you can see here the front of the case is made of aluminum. Can the fresh air go in? Does it even fit? If not, is it wiser to get Corsair Hydro Series H80i (www.corsair.com/en-us/hydro-series-h80i-high-performance-liquid-cpu-cooler) and place the radiator on top of my case(exhaust) and keep the front 2x120mm stock and add one more as intake on bottom. If you have any other idea let me know. Thank you. EDIT: The CPU fan running ~3000rpm and temp is around 40~43C on idle and save energy. When temp is going over 55C when running multiple programs and servers on localhost(tomcat, wamp) rpm is around 5500 and loud! I'm running Win8.1 CPU not overclocked PS: Due to my reputation i couldn't post the links that was necessary. I will edit ASAP.

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  • How are interrupts handled by dual processor machines?

    - by jeffD
    I have an idea of how interrupts are handled by a dual core CPU. I was wondering about how interrupt handling is implemented on a board with more than one physical processor. Is any of the interrupt responsibility determined by the physical board's configuration? Each processor must be able to handle some types of interrupts, like disk I/O. Unless there is some circuitry to manage and dispatch interrupts to the appropriate processor? My guess is that the scheme must be processor neutral, so that any processor and core can run the interrupt handler. If a core is waiting on a disk read, will that core be the one to run the interrupt handler when the disk is ready?

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  • How many registers in custom VM?

    - by DeadMG
    I'm designing a custom VM and am curious about how many registers I should use. Initially, I had 255, but I'm a little concerned about backing 255 pointers (a whole KB) on to the stack or heap every time I call a function, when most of them won't even be used. How many registers should I use?

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  • Redhat cpanel how to limit cpu for a perticular user.

    - by Ahmed M Fituri
    Hello, I have a web server with multiple users in it. one of these users uses mambo, and the cpu usage of this user is more than 90% which leads to a very slow performance of the machine, I have installed cpulimit version 1.1. but there is no particular command that limits the cpu per user. I need to limit this user for at least 50% . please help me ASAP. Thank you.

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  • Solaris X86 64-bit Assembly Programming

    - by danx
    Solaris X86 64-bit Assembly Programming This is a simple example on writing, compiling, and debugging Solaris 64-bit x86 assembly language with a C program. This is also referred to as "AMD64" assembly. The term "AMD64" is used in an inclusive sense to refer to all X86 64-bit processors, whether AMD Opteron family or Intel 64 processor family. Both run Solaris x86. I'm keeping this example simple mainly to illustrate how everything comes together—compiler, assembler, linker, and debugger when using assembly language. The example I'm using here is a C program that calls an assembly language program passing a C string. The assembly language program takes the C string and calls printf() with it to print the string. AMD64 Register Usage But first let's review the use of AMD64 registers. AMD64 has several 64-bit registers, some special purpose (such as the stack pointer) and others general purpose. By convention, Solaris follows the AMD64 ABI in register usage, which is the same used by Linux, but different from Microsoft Windows in usage (such as which registers are used to pass parameters). This blog will only discuss conventions for Linux and Solaris. The following chart shows how AMD64 registers are used. The first six parameters to a function are passed through registers. If there's more than six parameters, parameter 7 and above are pushed on the stack before calling the function. The stack is also used to save temporary "stack" variables for use by a function. 64-bit Register Usage %rip Instruction Pointer points to the current instruction %rsp Stack Pointer %rbp Frame Pointer (saved stack pointer pointing to parameters on stack) %rdi Function Parameter 1 %rsi Function Parameter 2 %rdx Function Parameter 3 %rcx Function Parameter 4 %r8 Function Parameter 5 %r9 Function Parameter 6 %rax Function return value %r10, %r11 Temporary registers (need not be saved before used) %rbx, %r12, %r13, %r14, %r15 Temporary registers, but must be saved before use and restored before returning from the current function (usually with the push and pop instructions). 32-, 16-, and 8-bit registers To access the lower 32-, 16-, or 8-bits of a 64-bit register use the following: 64-bit register Least significant 32-bits Least significant 16-bits Least significant 8-bits %rax%eax%ax%al %rbx%ebx%bx%bl %rcx%ecx%cx%cl %rdx%edx%dx%dl %rsi%esi%si%sil %rdi%edi%di%axl %rbp%ebp%bp%bp %rsp%esp%sp%spl %r9%r9d%r9w%r9b %r10%r10d%r10w%r10b %r11%r11d%r11w%r11b %r12%r12d%r12w%r12b %r13%r13d%r13w%r13b %r14%r14d%r14w%r14b %r15%r15d%r15w%r15b %r16%r16d%r16w%r16b There's other registers present, such as the 64-bit %mm registers, 128-bit %xmm registers, 256-bit %ymm registers, and 512-bit %zmm registers. Except for %mm registers, these registers may not present on older AMD64 processors. Assembly Source The following is the source for a C program, helloas1.c, that calls an assembly function, hello_asm(). $ cat helloas1.c extern void hello_asm(char *s); int main(void) { hello_asm("Hello, World!"); } The assembly function called above, hello_asm(), is defined below. $ cat helloas2.s /* * helloas2.s * To build: * cc -m64 -o helloas2-cpp.s -D_ASM -E helloas2.s * cc -m64 -c -o helloas2.o helloas2-cpp.s */ #if defined(lint) || defined(__lint) /* ARGSUSED */ void hello_asm(char *s) { } #else /* lint */ #include <sys/asm_linkage.h> .extern printf ENTRY_NP(hello_asm) // Setup printf parameters on stack mov %rdi, %rsi // P2 (%rsi) is string variable lea .printf_string, %rdi // P1 (%rdi) is printf format string call printf ret SET_SIZE(hello_asm) // Read-only data .text .align 16 .type .printf_string, @object .printf_string: .ascii "The string is: %s.\n\0" #endif /* lint || __lint */ In the assembly source above, the C skeleton code under "#if defined(lint)" is optionally used for lint to check the interfaces with your C program--very useful to catch nasty interface bugs. The "asm_linkage.h" file includes some handy macros useful for assembly, such as ENTRY_NP(), used to define a program entry point, and SET_SIZE(), used to set the function size in the symbol table. The function hello_asm calls C function printf() by passing two parameters, Parameter 1 (P1) is a printf format string, and P2 is a string variable. The function begins by moving %rdi, which contains Parameter 1 (P1) passed hello_asm, to printf()'s P2, %rsi. Then it sets printf's P1, the format string, by loading the address the address of the format string in %rdi, P1. Finally it calls printf. After returning from printf, the hello_asm function returns itself. Larger, more complex assembly functions usually do more setup than the example above. If a function is returning a value, it would set %rax to the return value. Also, it's typical for a function to save the %rbp and %rsp registers of the calling function and to restore these registers before returning. %rsp contains the stack pointer and %rbp contains the frame pointer. Here is the typical function setup and return sequence for a function: ENTRY_NP(sample_assembly_function) push %rbp // save frame pointer on stack mov %rsp, %rbp // save stack pointer in frame pointer xor %rax, %r4ax // set function return value to 0. mov %rbp, %rsp // restore stack pointer pop %rbp // restore frame pointer ret // return to calling function SET_SIZE(sample_assembly_function) Compiling and Running Assembly Use the Solaris cc command to compile both C and assembly source, and to pre-process assembly source. You can also use GNU gcc instead of cc to compile, if you prefer. The "-m64" option tells the compiler to compile in 64-bit address mode (instead of 32-bit). $ cc -m64 -o helloas2-cpp.s -D_ASM -E helloas2.s $ cc -m64 -c -o helloas2.o helloas2-cpp.s $ cc -m64 -c helloas1.c $ cc -m64 -o hello-asm helloas1.o helloas2.o $ file hello-asm helloas1.o helloas2.o hello-asm: ELF 64-bit LSB executable AMD64 Version 1 [SSE FXSR FPU], dynamically linked, not stripped helloas1.o: ELF 64-bit LSB relocatable AMD64 Version 1 helloas2.o: ELF 64-bit LSB relocatable AMD64 Version 1 $ hello-asm The string is: Hello, World!. Debugging Assembly with MDB MDB is the Solaris system debugger. It can also be used to debug user programs, including assembly and C. The following example runs the above program, hello-asm, under control of the debugger. In the example below I load the program, set a breakpoint at the assembly function hello_asm, display the registers and the first parameter, step through the assembly function, and continue execution. $ mdb hello-asm # Start the debugger > hello_asm:b # Set a breakpoint > ::run # Run the program under the debugger mdb: stop at hello_asm mdb: target stopped at: hello_asm: movq %rdi,%rsi > $C # display function stack ffff80ffbffff6e0 hello_asm() ffff80ffbffff6f0 0x400adc() > $r # display registers %rax = 0x0000000000000000 %r8 = 0x0000000000000000 %rbx = 0xffff80ffbf7f8e70 %r9 = 0x0000000000000000 %rcx = 0x0000000000000000 %r10 = 0x0000000000000000 %rdx = 0xffff80ffbffff718 %r11 = 0xffff80ffbf537db8 %rsi = 0xffff80ffbffff708 %r12 = 0x0000000000000000 %rdi = 0x0000000000400cf8 %r13 = 0x0000000000000000 %r14 = 0x0000000000000000 %r15 = 0x0000000000000000 %cs = 0x0053 %fs = 0x0000 %gs = 0x0000 %ds = 0x0000 %es = 0x0000 %ss = 0x004b %rip = 0x0000000000400c70 hello_asm %rbp = 0xffff80ffbffff6e0 %rsp = 0xffff80ffbffff6c8 %rflags = 0x00000282 id=0 vip=0 vif=0 ac=0 vm=0 rf=0 nt=0 iopl=0x0 status=<of,df,IF,tf,SF,zf,af,pf,cf> %gsbase = 0x0000000000000000 %fsbase = 0xffff80ffbf782a40 %trapno = 0x3 %err = 0x0 > ::dis # disassemble the current instructions hello_asm: movq %rdi,%rsi hello_asm+3: leaq 0x400c90,%rdi hello_asm+0xb: call -0x220 <PLT:printf> hello_asm+0x10: ret 0x400c81: nop 0x400c85: nop 0x400c88: nop 0x400c8c: nop 0x400c90: pushq %rsp 0x400c91: pushq $0x74732065 0x400c96: jb +0x69 <0x400d01> > 0x0000000000400cf8/S # %rdi contains Parameter 1 0x400cf8: Hello, World! > [ # Step and execute 1 instruction mdb: target stopped at: hello_asm+3: leaq 0x400c90,%rdi > [ mdb: target stopped at: hello_asm+0xb: call -0x220 <PLT:printf> > [ The string is: Hello, World!. mdb: target stopped at: hello_asm+0x10: ret > [ mdb: target stopped at: main+0x19: movl $0x0,-0x4(%rbp) > :c # continue program execution mdb: target has terminated > $q # quit the MDB debugger $ In the example above, at the start of function hello_asm(), I display the stack contents with "$C", display the registers contents with "$r", then disassemble the current function with "::dis". The first function parameter, which is a C string, is passed by reference with the string address in %rdi (see the register usage chart above). The address is 0x400cf8, so I print the value of the string with the "/S" MDB command: "0x0000000000400cf8/S". I can also print the contents at an address in several other formats. Here's a few popular formats. For more, see the mdb(1) man page for details. address/S C string address/C ASCII character (1 byte) address/E unsigned decimal (8 bytes) address/U unsigned decimal (4 bytes) address/D signed decimal (4 bytes) address/J hexadecimal (8 bytes) address/X hexadecimal (4 bytes) address/B hexadecimal (1 bytes) address/K pointer in hexadecimal (4 or 8 bytes) address/I disassembled instruction Finally, I step through each machine instruction with the "[" command, which steps over functions. If I wanted to enter a function, I would use the "]" command. Then I continue program execution with ":c", which continues until the program terminates. MDB Basic Cheat Sheet Here's a brief cheat sheet of some of the more common MDB commands useful for assembly debugging. There's an entire set of macros and more powerful commands, especially some for debugging the Solaris kernel, but that's beyond the scope of this example. $C Display function stack with pointers $c Display function stack $e Display external function names $v Display non-zero variables and registers $r Display registers ::fpregs Display floating point (or "media" registers). Includes %st, %xmm, and %ymm registers. ::status Display program status ::run Run the program (followed by optional command line parameters) $q Quit the debugger address:b Set a breakpoint address:d Delete a breakpoint $b Display breakpoints :c Continue program execution after a breakpoint [ Step 1 instruction, but step over function calls ] Step 1 instruction address::dis Disassemble instructions at an address ::events Display events Further Information "Assembly Language Techniques for Oracle Solaris on x86 Platforms" by Paul Lowik (2004). Good tutorial on Solaris x86 optimization with assembly. The Solaris Operating System on x86 Platforms An excellent, detailed tutorial on X86 architecture, with Solaris specifics. By an ex-Sun employee, Frank Hofmann (2005). "AMD64 ABI Features", Solaris 64-bit Developer's Guide contains rules on data types and register usage for Intel 64/AMD64-class processors. (available at docs.oracle.com) Solaris X86 Assembly Language Reference Manual (available at docs.oracle.com) SPARC Assembly Language Reference Manual (available at docs.oracle.com) System V Application Binary Interface (2003) defines the AMD64 ABI for UNIX-class operating systems, including Solaris, Linux, and BSD. Google for it—the original website is gone. cc(1), gcc(1), and mdb(1) man pages.

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  • Huge host CPU usage in idle vmware guest. Ubuntu 10.04 host, Vista SP2 guest

    - by themesandmodules
    I'm experiencing huge host CPU usage with an idle vmware guest. Host: Ubuntu 10.04 32-bit 2.6.32-24-generic-pae. (Very new install, i.e 24 hours ago) Hardware is Dell XPS M1530 laptop, 4GB ram. Intel Core II Duo T9300 2.50Ghz The virtualization setting "VT" or something is enabled in my bios. Guest: Completely fresh install of Windows Vista, upgraded to latest SP2 and all windows updates installed. 1024 - 1512MB ram allocated. Absolutely no other software installed on it, apart from VMWare tools. Situation When the guest is doing absolutely nothing, I watch with sysinternals process watch on the guest. This shows that system idle process is between 70 and 99%, usually around 95%. No actual process doing anything. On the host, I watch with top, I get cpu usage of 20% - 80%, usually around 30%. What I have tried Single and Dual processor available to guest - no change. Turn off all peripherals to guest - no network, drives, usb etc - no change. Turn off 3d acceleration for guest - perhaps a small improvement, or no change. Upping allocated ram to guest from 1024MB to 1512MB - no change. Yelling at vmware - no change. I have experienced a similar issue in the past, which was solved by setting the guest to have 1 CPU. This time that hasn't worked.

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  • Root cause for high CPU usage; which measurement to trust more: Windows Task Manager or Process Explorer?

    - by p.campbell
    Consider this Windows 8.1 machine (in-place upgrade from Windows 8) with differing reports on its CPU usage. The machine is idle, and has been for 3 days. There are no CPU intensive tasks running currently nor over the 3 day idle period. Windows Task Manager is reporting CPU usage constantly at an incredibly high value (and increasing over time!) at around 75%. Process Explorer from SysInternals reports that the CPU usage is much different at around 42% How does Process Explorer report 42.14% usage, but its columns report Idle at 57%, with the sum of the other processes not even approaching 10%? Which of these two values should I trust more, and why should it be trusted over the other measurement? How can I actually determine which process is causing Task Manager to report its values? These Proc Exp metrics were taken with Administrator privileges, and with option 'Show Details for All Processes' Click for larger view:

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  • SQL SERVER – Demo Script – Keeping CPU Busy

    - by pinaldave
    Recently face very interesting situation, during presentations at event, I was asked very famous questions: “My CPU is very high all the time, how can I reduce it?” This is very interesting question and there are many answers and a single blog post is not good enough to justify this subject. I presented few situation to the person who asked the question. The member of the audience who asked question came to me afterwords and asked me few detailed questions. To answer him, I quickly wrote query which simulate high CPU. Here is the script which I wrote which increased CPU from 10% to 80%. I was wondering if there is any similar script which can simulate high CPU usage. If you have share with me and I will publish with due credit. Here is my script for the same: USE AdventureWorks GO DECLARE @Flag INT SET @Flag = 1 WHILE(@Flag < 1000) BEGIN ALTER INDEX [PK_SalesOrderDetail_SalesOrderID_SalesOrderDetailID] ON [Sales].[SalesOrderDetail] REBUILD SET @Flag = @Flag + 1 END GO   Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Which opcodes are faster at the CPU level?

    - by Geotarget
    In every programming language there are sets of opcodes that are recommended over others. I've tried to list them here, in order of speed. Bitwise Integer Addition / Subtraction Integer Multiplication / Division Comparison Control flow Float Addition / Subtraction Float Multiplication / Division Where you need high-performance code, C++ can be hand optimized in assembly, to use SIMD instructions or more efficient control flow, data types, etc. So I'm trying to understand if the data type (int32 / float32 / float64) or the operation used (*, +, &) affects performance at the CPU level. Is a single multiply slower on the CPU than an addition? In MCU theory you learn that speed of opcodes is determined by the number of CPU cycles it takes to execute. So does it mean that multiply takes 4 cycles and add takes 2? Exactly what are the speed characteristics of the basic math and control flow opcodes? If two opcodes take the same number of cycles to execute, then both can be used interchangeably without any performance gain / loss? Any other technical details you can share regarding x86 CPU performance is appreciated

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