Computer multi-tasking: How far do YOU push it ?

[Seeker47]

(With apologies to our resident pollster.)

We've seen powerful dual-core processors around for at least a couple years now, with a lot of ads lately for tri-core and quad-core turning up more recently. I'm in the process of updating a couple systems to dual-core, which is about as far as I care to go for the present. It should be noticeably better for a lot of things than the single core P4 I've been using the last few years.

I'm wondering what folks here have to say about multi-tasking that includes video -- whatever hardware you're using, and whichever video apps, if it matters. There are some posts I've seen in the past, where the poster was running some fairly impressive rig, and claimed to be doing major video + internet stuff + BEEEG spreadsheet recalcs or database sorts (or some equivalent combo) all at the same time on the same box. Was that person just blowing smoke ? Is this really practical, or effective, or safe, even with muscular hardware ? If video is there in the mix, I would always wonder about dropping frames, or something like that. I know someone who makes a lot of slideshows but has had a number of them ruined by forgetting that a regular Norton update was going to happen overnight, at the same time the slideshow was "cooking". But that was on an older single core. My own rule of thumb so far has been that if I'm burning a DVD, or running ConverX, or Shrink, or anything like that, it was pretty much the only thing the computer was doing at the time. I might open a Notepad window briefly (pretty low rent in cpu terms, I think), or play a few hands of Solitaire or Blackjack while waiting, if in a riskier mood.

[redwudz]

It kind of depends on what I am doing. When I encode with a codec that can use all four cores of my CPU at 100%, I start it before I go to bed, or just use another computer, usually my laptop, for other minor operations.

I go by CPU % of usage. If the program is only using one core or a small part of all cores, no problem running other applications. When it's at 100% of all cores, nothing else will run anyway.

That said, I find I can run several programs, email, web surfing, spreadsheets, and other lower usage programs at the same time with no noticeable effect on any of them. I definitely like multiple core CPUs, especially if they can run at 3Ghz or more.

I guess, to add, you shouldn't be dropping frames when running a encode and other programs, it will just run all of them slower. I see the dropped frames problem more with capturing, and that is more often a result of HDD access problems, not the CPU. But it still pays to watch your CPU % of use.

[RabidDog]

Multi-tasking these days mostly isn't held back by the CPU's .. its more often the disk access that is the problem. Any job that requires any sort of Medium to high CPU usage inevitably requires to be fed with data of whatever sort, and this is where the Hard disk access slows everything down. Burning a dvd for instance is actually a very Non cpu intensive operation, its more intensive of the PCI bus.. if anything else grabs it for a while you risk a bad burn .. hence Mfrs implementing buffer under run. You should be able to play team fortress and burn a DVD at the same time as they are generally using different bits of your PC, and neither is really stressing the CPU. There are very few apps that are CPU bound, that are used at home, except video re-encoding, and even that benefits greatly from faster disks.
Everyone these days is going Multi-Core like they're going HDTV.. there isnt really any other choice, except maybe NetBooks

[INFRATOM]

Every program that is opened takes away part of your RAM, So you have to estimate how many programs are multitasking so it does not have to page too often and with slow HD it gets worse. With multitasking going to 64 bit and lots of memory is the first step. Also one can change the priority of the threads so if something kicks in like the example mentioned it would not downgrade the process.

[lordsmurf]

Multitasking while video or audio is encoding is not only a bad idea, but outright stupid. It is too easy to introduce artifacts, and it happens all the time, especially to folks who insist "I can do it fine". This task requires a lot of CPU and hard drive access, only small/mild amounts of RAM.

When it comes to photo work, I can only do one task at a time. Bridge CS3 and Photoshop CS3 eat ups tons and tons of RAM and CPU, and there is often a lot of disk writing involved. Trying to do anything else almost almost clusterfucks the system, forcing a reboot.

I cannot design very well in InDesgn without closing most other software. It's a real whore with swap file, RAM, and hard drive activity. Not so much on CPU. Doing too much can crash ID, and sometimes even "saved" files can be corrupted if they close due to crash. Save often, and "save as" for all new saves. This is an ancient flaw, an artifact from the PageMaker years.

I can multi-task web browsing/research, Web design, e-mail and typed documents. For anything else, I have to start closing tasks and programs. This is very minimally impacting on a system, but a person can only move so fast anyway.

For these scenarios, I'm using Intel dual-core systems with 4GB RAM.

My way of multi-tasking (and indeed the method of many professionals) is to use several computers on a single desk, with a KVM. Or by using a remote protocol (RDP, VNC, etc) to remotely access another system.
Example:
- Computer 1 is for checking e-mail, Web research, HTML editing, playing an MP3, etc.
- Computer 2 is performing server backups (up/down + SQL), lot of network use and writing of files.
- Computer 3 is authoring a disc, and will then be used to duplicate from the master.
- Computer 4 is encoding a video that was edited in Premiere CS3.
- Computer 5 has Bridge open, and photos are being taken and sorted, sent to the network share on an as-needed basis. Copying new files off the CF card to the local drive for culling and correcting.
- Computer 6 is the server itself, through an RDP off the first, with a concurrent browser to the admin panel for shortcut tasks.
- Computer 7 is via a VNC session, synchronizing research docs and working files between offices.

Sometimes it's two or more desks, and quite often at least 1-2 systems are laptops for travel, while the others are desktops (some Shuttle, some micro-setups) on the KVM. Many of them are also equipped with multi-monitor support, because we need all the work room we can get.

Multi-computer multi-tasking is far more complicated AND productive than single-system tasking.

Ah, yes ... welcome to my world. 8)

Using one computer to "multitask" is amateur.

[rallynavvie]

I have the opposite issue with the Adobe apps as lordsmurf does. For print layouts I generally have Photoshop, Bridge, Illustrator, and InDesign open all at once and sometimes Encore when doing menu layouts. Usually PS and Illustrator reside on my main display with the InDesign layout showing on the other display. I've encountered similar issues to what lordsmurf mentioned before but I found that having dedicated scratch drives makes a huge difference with these applications. I use two old 36GB 15krpm U320 drives in RAID 0 for their scratch space ONLY. If the stripe goes bad the applications can rebuild the missing scratch data but since I'm only using them for maybe 3-4 hours on any given day they haven't had issues with the array corrupting. I have always had plenty of memory and CPU power available. I've also noticed that my systems with ECC memory have had far less issues with encoding and working with large files despite the slightly higher latency.

As for video encoding I would guess that you could get away with "background" encoding if you were using a dedicated disk array for it, like encoding between two SATA drives on the same controller. You'd also need to specify how many cores to use with the encoder so you aren't taking cycles away from the encoding app. Too many things need to be perfect for the encode to come out perfect so I would agree with the above posters that say not to do it.

[jagabo]

Real time processes like video capture and DVD burning can run in to problems if you multitask. With these types of applications the CPU, hard drive, etc. must be available at certain times or data will be lost. But non-realtime processes like video encoding (file to file) should have no problems at all on a system that is working properly. Each application runs in its own address space and cannot touch another application's data. Obviously, if you run so many applications at once that you end up VM thrashing everything will slow to a crawl.

I very often have a video conversion (typically AviSynth and VirtualDub, sometimes HcEnc) running (at low or idle priority) in the background while I do other stuff. Never a problem. With either the foreground app or the conversion.

When I had a Hauppauge PVR-250 (PCI hardware MPEG encoder) I never worried about what else I was doing while capturing. I once tried to get it to drop or corrupt frames while capturing. I started a cap, then defragged a drive, copied a large folder from one drive to another, and started up a 3d game. WinTV2000's display got out of A/V sync but there were no problems at all with the captured MPEG file.

On the other hand, long ago with a Matrox eTV card (raw YUY2 capture, software compression) I had to be careful not to do anything else while capturing, espcially at full D1. Even just starting up a web browser or email could cause dropped frames.

Obviously, if you are running some rogue application that manages to crash Windows your conversion will crash along with it. In my experience, graphics driver bugs are the biggest cause of system crashes. Since they run in kernel mode they can thrash whatever memory they want. I always use WHQL certified graphics drivers because they usually have fewer bugs than the latest beta releases.