On Fri, Jan 27, 2023 at 04:46:16PM -0700, Shuah Khan wrote: > +strace tool can be used to trace system calls made by a process and signals > +it receives. a process to the perf, stress-ng, paxtest workloads. System "... to trace system calls made by a process (which can be perf, stress-ng, paxtest workloads, or neither)." > +Before we can get started we will have to get our system ready. We assume "Before we can get started the system must be prepared first." > +Browsing kernel sources :: "To browse kernel sources, you will need:" > +Workload overview > +================= > + > +We used strace to trace perf bench, stress-ng and paxtest workloads to "In this section, we use strace to trace ..." > +show how to analyze a workload and identify Linux subsystems used by > +these workloads. We hope this process can be applied to trace workload(s). > +We will go over the workloads first. "This process can also be applied to trace other workloads." > + > +perf bench (all) workload: > +-------------------------- > + > <snipped> > + > +Stress-ng netdev stressor workload: > +----------------------------------- > + > <snipped> > + > +paxtest kiddie workload: > +------------------------ > + > <snipped> Drop trailing colon from these subsection texts. > +We used the “-c” option to gather fine grained information. ``` The basic usage is strace <command>. To run verbose tracing, specify -v to strace. To generate the report, specify -c option. ``` > +Now let’s look at `cscope <https://cscope.sourceforge.net/>`_, a command > +line tool for browsing C, C++ or Java code-bases. We can use it to find > +all the references to a symbol, global definitions, functions called by a > +function, functions calling a function, text strings, regular expression > +patterns, files including a file. > + > +We can use cscope to find which system call belongs to which subsystem. > +This way we can find the kernel subsystems used by a process when it is > +executed. To use it navigate to the source code directory. Here we are > +analyzing the kernel source tree. I guess "you" is better fit for the wording above? > +We used perf stat and perf bench options. For a detailed information on the > +perf tool, run perf -h. "In this section, we highlight stat and bench options. For help on other options, see perf -h." > +**perf bench all** command runs the following benchmarks: :: Either don't markup that command or inline it (``perf bench all``). Also, use bullet list for benchmarking list below. > + > + sched/messaging > + sched/pipe > + syscall/basic > + mem/memcpy > + mem/memset > + > +The netdev stressor starts N workers that exercise various netdevice ioctl > +commands across all the available network devices. The following ioctls are > +exercised: :: > + > + SIOCGIFCONF, SIOCGIFINDEX, SIOCGIFNAME, SIOCGIFFLAGS > + SIOCGIFADDR, SIOCGIFNETMASK, SIOCGIFMETRIC, SIOCGIFMTU > + SIOCGIFHWADDR, SIOCGIFMAP, SIOCGIFTXQLEN Again, use bullet list instead. > + > +The following command runs the stressor: :: > + > + stress-ng --netdev 1 -t 60 --metrics command. Simply end the sentence with double colon to make the code block above. > + > +We can use the perf record command to record the events and information > +associated with a process. This command records the profiling data in the > +perf.data file in the same directory. > + > +Using the following commands you can record the events associated with the > +netdev stressor, view the generated report perf.data and annotate the to > +see the statistics of each instruction of the program. :: "... view the generated report and statistics::" > + > + perf record stress-ng --netdev 1 -t 60 --metrics command. > + perf report > + perf annotate > + > +What is paxtest and how do we use it? > +===================================== > + > +paxtest is a program that tests buffer overflows in the kernel. It tests > +kernel enforcements over memory usage. Generally, execution in some memory > +segments makes buffer overflows possible. It runs a set of programs that > +attempt to subvert memory usage. It is used as a regression test suite for > +PaX, and will be useful to test other memory protection patches for the > +kernel. > + > +paxtest provides kiddie and blackhat modes. paxtest kiddie mode runs in > +normal mode, whereas blackhat mode tries to get around the protection of > +the kernel testing for vulnerabilities. We focus on the kiddie mode here > +and combine "paxtest kiddie" run with "perf record" to collect CPU stack > +traces for the paxtest kiddie run to see which function is calling other > +functions in the performance profile. Then the "dwarf" (DWARF's CFI - Call > +Frame Information) mode can be used to unwind the stack. The resulting > +report can be viewed in call-graph format as follows: :: > + "... The resulting reported can be viewed in dwarf call-graph format by::" > + perf record --call-graph dwarf paxtest kiddie > + perf report --stdio > + > +Tracing workloads > +================= > + > +Now that we understand the workloads, let's start tracing them. What are the workloads? I don't see any definition here. > + > +Tracing perf bench all workload > +------------------------------- > + > +Run the following command to trace perf bench all workload: :: > + > + strace -c perf bench all > + > +**System Calls made by the workload:** What about third level heading (with tilde underline)? > + > +The following table shows you the system calls, number of times the system > +call was invoked, and the Linux subsystem they fall under. "Below table is the list of syscalls, with number of times each is invoked, and the corresponding subsystem:" > +**System Calls made by the workload:** > + > +The following table shows you the system calls, number of times the system > +call was invoked, and the Linux subsystem they fall under. Same here. > +**System Calls made by the workload:** > + > +The following table shows you the system calls, number of times the system > +call was invoked, and the Linux subsystem they fall under. Again, same here. But I guess the syscall tables are from the example workload (YMMV)? Thanks. -- An old man doll... just what I always wanted! - Clara
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