ltrace

How does ltrace (library tracing tool) work?

由 ぐ巨炮叔叔 提交于 2019-12-22 18:37:26
问题 How ltrace works? How does it find out that program's calling library functions? Is there any common code path that all calls to library functions come through? Maybe ltrace is setting breakpoint in this common code path? Thanks! 回答1: Dynamic executables have a symbol table used by the linker when resolving references that need to be connected to library functions. (You can see this yourself by running objdump -T /path/to/binary ). This symbol table is accessible by other tools -- such as

No output when running ltrace

由 风格不统一 提交于 2019-12-19 20:47:30
问题 As the title says, ltrace does not work properly on my system. It shows no output in most cases, like $ltrace ls [usual ls output] +++ exited (status 0) +++ $gcc hello.c $ltrace ./a.out Hello world! +++ exited (status 0) +++ I'm using the latest ltrace version (from package 0.7.3-5.1ubuntu4 ), I even tried recompiling from source with no difference. I'm using Ubuntu 16.10 , kernel 4.8.0-42-generic . gcc version is 6.2.0 . Weird thing is, binaries downloaded from the Internet seem to work,

How to use ltrace for mpi programs?

由 穿精又带淫゛_ 提交于 2019-12-10 23:37:18
问题 I want to know how to use ltrace to get library function calls of mpi application but simply ltrace doesn't work and my mpirun cannot succeed. Any idea? 回答1: You should be able to simply use: $ mpiexec -n 4 -other_mpiexec_options ltrace ./executable But that will create a huge mess since the outputs from the different ranks will merge. A much better option is to redirect the output of ltrace to a separate file for each rank. Getting the rank is easy with some MPI implementations. For example,

building ltrace for android

由 只谈情不闲聊 提交于 2019-12-08 04:02:31
问题 I'm trying to build ltrace for android. I've tryed a few ways none worked.... I was able to produce a bin file compiling the source code using crosstool-ng's arm-unknown-linux-gnueabi and ./configure -host=arm-linux-gnueabi -target arm-linux-gnueabi CC=/path/to/toolchain/bin/arm-unknown-linux-gnueabi-gcc -prefix=/path/to/destination/folder but when i tried to execute that bin on android i get: ./ltrace: not found Any ideas? 回答1: Looks like executable bit is not set? You can check by doing ls

How does ltrace (library tracing tool) work?

由 ε祈祈猫儿з 提交于 2019-12-06 08:25:41
How ltrace works? How does it find out that program's calling library functions? Is there any common code path that all calls to library functions come through? Maybe ltrace is setting breakpoint in this common code path? Thanks! Dynamic executables have a symbol table used by the linker when resolving references that need to be connected to library functions. (You can see this yourself by running objdump -T /path/to/binary ). This symbol table is accessible by other tools -- such as ltrace -- as well, so it's trivial to determine which functions need to be hooked and walk that list

Linux性能优化笔记

由 谁都会走 提交于 2019-12-04 18:26:13
Linux性能优化笔记 Optimizing Linux Performance: A Hands-On Guide to Linux Performance Tools 1 性能追踪建议 记录一切可以搜集的信息，即使其中的一些信息在当时看起来没有太大的用途。 2 性能工具：系统CPU 在Linux下，进程有可运行和阻塞两种状态。可运行进程有分为两类：已经获得CPU时间正在运行的一类，和等待CPU时间的一类。在Linux系统中，运行队列长度就是系统中可运行状态的进程数量（平均值）。被阻塞的进程也可以分为两类：被I/O阻塞的进程，以及被系统调用阻塞的进程。一个CPU一次只能执行一个进程。在进程调度时，CPU需要把当前进程的信息保存起来，从内存中加载下一个进程的信息。这个过程叫做上下文切换。上下文切换会导致CPU中的高速缓存和流水线刷新，对性能有负面影响。为了公平的分配CPU时间，Linux会周期性的中断进程。通常，这种周期性上下文切换的数据可以作为考察系统上下文切换数量的基准： cat /proc/interrupts | grep timer; sleep 10; cat /proc/interrupts | grep timer; 如果系统中断频率高于定时器的频率，说明进程经常陷入I/O等待或系统调用（比如休眠）等待之中。 在任意时刻，CPU可以处于以下几种状态： -空闲

ltrace for Android build

由 跟風遠走 提交于 2019-12-02 04:28:29
问题 guys. I'm trying to buidl ltrace for Android from this repo https://android.googlesource.com/platform/external/ltrace/ . So i've installed android-ndk, then i've done everything like in android manual for using standalone toolchain for arm and android-16 (https://developer.android.com/ndk/guides/standalone_toolchain.html Advanced method from here). Then i've cloned the repo and in root directory run ./autogen.sh . After that ./configure -host=arm-linux . And i've received an error: "configure

ltrace for Android build

由 十年热恋 提交于 2019-12-01 23:02:43
guys. I'm trying to buidl ltrace for Android from this repo https://android.googlesource.com/platform/external/ltrace/ . So i've installed android-ndk, then i've done everything like in android manual for using standalone toolchain for arm and android-16 ( https://developer.android.com/ndk/guides/standalone_toolchain.html Advanced method from here). Then i've cloned the repo and in root directory run ./autogen.sh . After that ./configure -host=arm-linux . And i've received an error: "configure: error: *** libelf.h or gelf.h not found on your system" So it's look like i need include libelf from

No output when running ltrace

由 て烟熏妆下的殇ゞ 提交于 2019-12-01 19:14:44
As the title says, ltrace does not work properly on my system. It shows no output in most cases, like $ltrace ls [usual ls output] +++ exited (status 0) +++ $gcc hello.c $ltrace ./a.out Hello world! +++ exited (status 0) +++ I'm using the latest ltrace version (from package 0.7.3-5.1ubuntu4 ), I even tried recompiling from source with no difference. I'm using Ubuntu 16.10 , kernel 4.8.0-42-generic . gcc version is 6.2.0 . Weird thing is, binaries downloaded from the Internet seem to work, correctly displaying the library calls. What am I missing? Is anyone able to reproduce the issue? This may
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