Intel's "G"reen Processor

Looks like Intel is finally catching up with other high tech companies in offering "green" processors. Sun's Niagara class of processors have been around for a while now, but Intel is joining the band wagon now. Read about Xeon G 's power savings in this article.

posted by Amandeep 8/30/2007 08:28:00 PM | PERMALINK

Fixing Performance Issue with Windows XP

A few days ago my laptop running Windows XP started to manifest unbearable performance degradation. It seemed to take forever to do even simple things. At this point it was clear that something is not right. I opened the "Task Manager" and clicked at the performance tab. CPU was 100% busy. What was taking up all the CPU resource? Clicking on the "Processes" tab and then sorting the processes based on CPU usage I saw that qttask.exe was the culprit. I killed this (supposed to be Quick Time related) process to free up some CPU resource in order to make progress. I say "supposed to be..." because the process was not behaving normally - indicative of a virus infection. (I had not updated my anti-virus definition files for a while - my mistake!). I uninstalled / removed any unused software from the system. Cleaned up the "auto start" programs - this considerably reduced start up time. Further I Downloaded the latest anti virus and let it loose to clean up the system. Once that was done (yes it did find threats) - enabled the firewall for future protection.
A quick google search revealed a couple of useful links on performance recovery and getting rid of malware. I am also linking a couple of additional resources here, related to performance tuning and protection against spyware.

posted by Amandeep 8/28/2007 10:35:00 PM | PERMALINK

Modifying Hardware Capability (HCAP) Bits of an Object File

Many times in order to optimize software performance programmers use specific compiler flags that generate code tuned to a given hardware architecture. In fact, at times we'd write tight loops in assembly using processor specific instructions to squeeze that extra bit of performance. The peripheral code in "c" or C++ can then call this assembly routine to do the actual intensive work. Further to make the program portable to other platforms code could be enhanced to call different assembly routines based on runtime detection of the hardware architecture. I remember having used an array of function pointers with a separate assembly routine for each kind of platform/processor.

The problem is that if hardware specific instructions gets executed on a different processor the results may be undefined - including the possibility of program getting killed by SIGILL (illegal instruction signal). Well this is where SunStudio comes in - it programs HCAP bits that tell the linker at runtime about presence of such instructions in the binary. At run time the linker would give a message like "fatal: hardware capability unsupported" on detecting such a scenario. Now what if, the hardware specific instructions were never going to get executed on this processor based on program logic, as in the example above? Well, in this case instead of getting forced to create multiple binaries, one can modify the bits in the program binary that tell the linker about the presence of these hardware specific capabilities. Checkout this article and blog that teach how to modify these (HCAP) bits.

posted by Amandeep 8/22/2007 07:01:00 PM | PERMALINK

Observability and Debugging

Came across Observability OpenSolaris community. While the list of observability tools seems pretty extensive, the links with details about these tools had sparse information. This article, named Application Troubleshooting: Alternate Methods of Debugging on the other hand, though restricted to application debug details many useful tips. The article covers uses of "truss", proc utilities, gcore, coreadm, LD_PRELOAD and watchmalloc.

posted by Amandeep 8/21/2007 01:26:00 AM | PERMALINK