Page fault problems in XP - app causes thousands/sec

[spidey07]

I thought a page fault is when a page of memory is requested and the OS (windows xp) has to get it from disk.

Well there is a particular application that is running slower than dog doo and using performance monitor/task manager I can see that CPU is at 100% and the page faults increase thousands of time per second and the disk thrashes. Funny part is there is plenty of physical memory to use.

In this example the machine has 512 memory and about 256 physical free. Is the app (an enterprise query/reporting tool) just very poorly written or is XP just having a hard time managing memory?

Any ideas on what to look for our troubleshoot or recommended page file settings for XP? I've tried some googling but am not having much luck.

Thanks bunches in advanced!
spidey

 

[Nothinman]

There are two types of pagefaults, soft and hard. A soft fault means the data is in memory and the page just needs mapped back into the address space of the faulting app, no I/O is needed just an alteration of the page tables. Hard pagefaults mean disk I/O is needed, either something has to be faulted in from the pagefile or from another file on disk like an executable file or library.

I would first find out all the libraries the app is using, like Oracle, SQL Server, plain ODBC, etc. Perhaps it's a problem with one of them or even a versioning problem (i.e. using Oracle 8.x libs when 9.x is needed). Of course test it on another 'known good' machine too, it could be something specific to the machine it's currently on.

 

[CTho9305]

I've never heard of a "soft" page fault.

 

[Nothinman]

That doesn't mean it doesn't exist =)

 

[CTho9305]

I didn't mean it doesn't 😉.

 

[spidey07]

Well I've asked the PC and app guys to get the software vendor involved. (I'm a network architect, don't mess with PCs much) the software used to be called adaytum and is now "cognos".

I've even done full fledged network analysis/packet sniffs of the app and all the work is indeed happening on the PC. These machines are the latest and greatest with 1 gig of memory. The memory helps some in that instead of taking 10 minutes to do a simple record change it takes 8. But something is going on with this app that doesn't make any sense. Either very poor algoritihm or poor memory management.

Thanks for the explanation nothingman, makes sense. But what doesn't make sense is why is this thing so resource intensive? Maybe the database is poorly designed or the data has simply out grown the application.

Oh well, we'll see what the vendor says. lemme guess - "OH, you want to do THAT? Well we sell another product that scales to that size and it only costs 300,000 dollars. How much software would you like to buy?"
🙂

 

[Nothinman]

ugh cognos. I havn't personally messed with it but one of our departments started too, it was basically abandoned when the one guy that knew how to set it up got let go and noone wanted to pick it up because all he did was bitch about it.

If it's really causing a lot of page faults and there's plenty of free memory it's a userland problem, something that bad in the OS itself would have been caught early on even by MS QA people.

 

[CTho9305]

Originally posted by: Nothinman
ugh cognos. I havn't personally messed with it but one of our departments started too, it was basically abandoned when the one guy that knew how to set it up got let go and noone wanted to pick it up because all he did was bitch about it.

If it's really causing a lot of page faults and there's plenty of free memory it's a userland problem, something that bad in the OS itself would have been caught early on even by MS QA people.

I found it relatively hard to learn... but once you get it all set up, its Cubes (powerplay) are REALLY cool. For simple report generation (impromptu), it really isn't much better than ActiveReports, which costs all of ~$200 and can be learned by anyone in an hour.

edit: and just generating simple reports on our webserver was surprisingly difficult. With activereports, we registered a DLL, and just wrote a simple dll in VB to do the report generation. Cognos was much harder, and involves a lot more steps.