We started the application (it was a 32-bit application, therefore a 4-gigabyte address space), and it did run out of address space.Īs my first measurement, I decided to measure the address space size upon entering and exiting the function that loaded records from the database. However, this exercise was going to take 7 days! Not having 7 days, I agreed to have the user manually load the database with the 30,000 records. But when I restart the database, the application runs out of address space."īeing a skeptic, I wanted to observe the database doing a one-at-a-time insertion. The problem was explained in the following manner: "When I insert records into the database through my application one at a time, I can insert 30,000 records with no issues. My customer was receiving an "ENOMEM" while starting his application.
With an 8K write size: megabytes/sec= 984.639115Īnalysis of the DTrace-enabled root cause led to a modification yielding twice the throughput! Let's try to find out what is causing the cross calls.Ĭonsider a modified xcallsbypid.d from the the DTrace Toolkit:Ĭopy using at 1024 byte write size: megabytes/sec= 445.227011 In the Solaris OS, the examples from the DTrace user guide are found in /usr/demo/dtrace.Ĭopy CPU minf mjf xcal intr ithr csw icsw migr smtx srw syscl usr sys wt idlĢ6 0 0 234 132 0 288 11 31 204 0 630 0 1 0 99Ģ9 0 0 219 198 0 447 11 32 194 0 466 0 1 0 99 Two of my favorite sources for sample DTrace are /usr/demo/dtrace and the DTrace Toolkit. When I need or want to use DTrace, I "borrow" someone else's DTrace and make a few modifications to suit my needs and environment. However, if you are not using a new language daily, details soon become hazy. The DTrace Documentation has hundreds of pages, and yes, I read them all initially. By default, the contents of the aggregation are printed upon exit from the script. The action is an aggregation (designated by the that contains the count by function name of the system calls executed. The action occurs only when the pid (process id) matches the first parameter passed on the command line. The predicate ( /pid = $target/) determines if the action ( = count() ) is performed. In this example, we are interested only in the entry to the function as opposed to the return. The function designation is likewise omitted, so the script matches on any function. The module designation is omitted so the script matches on any module. In the preceding script, syscall is the provider.
#Netmap example code#
DTrace differs from traditional tools in that code is instrumented dynamically. Since then, DTrace has been made available in FreeBSD and Max OS X. These DTrace-inspired answers lead to increased performance.ĭTrace, or dynamic tracing, was first available in the Solaris 10 OS in 2004. Using mpstat and prstat information, the tutorial illustrates which questions one should ask and how one can use DTrace to answer these questions. The tutorial emphasizes practical real-world use of DTrace, as opposed to an introduction to language syntax. This tutorial uses DTrace to analyze several applications.
#Netmap example mac os#
Since its introduction, it has been implemented in other operating systems, the most noteworthy being FreeBSD and Mac OS X. DTrace, or Dynamic Tracing, is a powerful diagnostic tool introduced in the Solaris 10 OS.
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