XP system cache question...

[joeMan]

Maybe this is no problem (it probably isn't) since I can still run Photoshop CS, play World of Warcraft, or run SIMS2 on this machine without issue...but still I want to know what's going on here:

One of the PC's at my house has 1GB of PC3200. Upon booting up XP Task Manager> Performance tab> physical memory (K) section says:

Physical Memory (K)
Total 1047024
Available 736516
System Cache 188804 <--- NOTE the relatively low cache upon boot-up

But I have been watching it for about 10 minutes now and ever so slowly the system cache number is ticking upward...and the reason I have posted this is because on this machine it always ticks up to around 800000K and then levels off around there and stays there until I reboot.

So eventually it looks like this:

Physical Memory (K)
Total 1047024
Available 736515 (this doesn't change despite the cache getting large)
System Cache 800000 (+/-)

I have gone through all the things I can think of - manually reviewed Processes, run Disk Cleanup, AVG, Adaware, Spybot S&D, Defragged, rebooted then double check Administrative Tools> Services, and double checked Task Manager>Processes tab...

I can't figure it out...:scratch: Just in the time I have written this post it has steadily crept upward from 189000-ish to 214000. And I assure you it will slowly creep until it reaches 800000 and it will stay there.

I guess the reason it annoys me is because on my rig at work, with 2GB OCZ - I run the same progs (except SIMS2) and many more - often simultaneously...like I will have WoW going in windowed mode on one monitor while Outlook, IE7-beta and Winamp running at the same time on the other monitor and the cache numbers don't do that.

I have Googled around on it a bit, but I haven't found anything really hitting the bullseye. Any of you know what is going on here?

Thanks, jM.

[Just Learnin']

Probably not the same issue but this was caused by NAV on this system: Link (http://www.hydrogenaudio.org/forums/index.php?showtopic=42638) :scratch:

[BeeHay]

i was reading around and a few ppl have had this prob with an ati video card messing the cache count up...

you runnin ati in there?

[joeMan]

you runnin ati in there?

Sure am, X850XT PE AGP and ATI Tool loaded on boot via registry...however, Task mgr processes shows it using the usual very low resources...

[joeMan]

Probably not the same issue but this was caused by NAV on this system: Link (http://www.hydrogenaudio.org/forums/index.php?showtopic=42638) :scratch:
Thanks JL. I read through that thread...although I'm not running NAV (and wouldn't if you paid me...lol). Still nuthin...

[Just Learnin']

Just for info sake my total physical memory is 2095646 and the system cache eventually rises to about 1640000. I never concerned myself with it though, till you made mention that is. :scratch: Percentage wise pretty much the same though.

[joeMan]

I am beginning to think it really isn't of concern at all...it is more of an annoyance only because I don't know why that number grows (and to a pretty big number sometimes...). I need to keep looking and reading more about it until I understand it better.

What I am in search of next is how can I tell what programs are directly or immediately "in possession of" or "reserving" or "utilizing" that System Cache number allocated in Task Manager...

[RyderOCZ]

You probably already thought of this Joeman, but what is this set to on the problem PC? Is it different from your "normal" PC?

http://www.bleedinedge.com/crew/ryderocz/Files/cache.jpg

[joeMan]

Good Lord allmighty Ryder...I seriously cannot believe it - you are right. Somehow, for some unknown reason that Memory Usage setting got switched over to System Cache.

:beat: :beat: I can't believe the answer was so simple. :lol:

Now...:scratch: ...how the HECK did it get switched? Hmmmm....???

[RyderOCZ]

Well....this is the same as "largesystemcache = 1" (or something like that, not sure of the exact terminology..the benchers use it for superPi, etc) in the boot.ini I believe. I also think that during the install that can be set...based on one of the questions that gets asked...but not sure, never tried it.

Did you build it? That would probably negate the notion that the install had anything to do with it....if your like me you install everything the same time after time after time.

[joeMan]

JL, you getting all this? This is good stuff man.

Yes, I did build it...it's my daughters. I am going to check that LargeSystemCache=1 in the registry...I think I was messing with this setting within the past few weeks.

jeeez louise, burning the candle at both ends has dulled my wits a bit :coocoo: :yup: .

A couple minutes later...
OK, that was it...I verified by changing it to 1, rebooting then looking at that screen you posted and sure enough setting that value to 1 sets the other to System Cache. I had changed that registry setting to 1 for something I was reading somewhere a few weeks ago said to do so for such and such reason, tweak tweak malaaaa malala maaalllllaaaaaaaa... . . .obviously I never finished the full experiment at the time - but I have now.

Problem solved, question answered, itch scratched.

A couple minutes later...
Here (http://technet2.microsoft.com/WindowsServer/en/Library/efa621bd-a031-4461-9e72-59197a7507b61033.mspx?mfr=true) is a short and to-the-point read about that LargeSystemCache setting.

Also, please read Tweak #4 here (http://kadaitcha.cx/performance.html) - also very informative..and more interesting than that first link above.

[RyderOCZ]

:rock: :rock:

:thumb: :cool:

[joeMan]

So tell me if I understand that information right:

If you set the Memory Usage to System Cache (or change LargeSystemCache to =1, same thing) - you tell the OS to load the pages needed into memory, then after you close the app(s), those pages stay there ready to rock at a MUCH higher I/O rate (because they are already resident in physical RAM) than if they were paging to/from your HDD.

-AND-

The reason the numbers can look in Task Manager> Performance tab under Physical Memory (K) like:

Total 1178608
Available 870000
System Cache 860000

...which if you add available ans system cache together it adds up to 1.73GB total - WAY more than total physical RAM <---and this is what confused me the most. But it's really okay because the system cache isn't permanantly occupying that physical memory - it is just "caching" :bonk: DUH! the pages there in case they are called upon again - but they can be re-allocated as per "normal - non-cached" behavior as needed, all managed by the OS as per usual.

Do I have that right?

[Just Learnin']

My largesystemcache is set to 0, My performane/advanced setting is set to programs so....:scratch: Also my PC has been on all day now and the Task Manager shows the system cache at only 44,700 k at this time, I am just now running a virus scan and it is climbing, it rose to over 1,700,000 k in 2 1/2 minutes and then fluctuated between 1,480,000 and almost 1,760,000 after stopping the scan it is hanging at around 1,760,800 still at this level 5 minutes later. Will check back in a while to see what becomes of it.

Well after an hour it's still up at 1,708,400 will see what it is like tomorrow.

[Just Learnin']

Twelve hours later and it is at 1,232,276 k ...........

[joeMan]

Hmmmm...JL what is:

START> Run> Regedit> HKEY_LOCAL_MACHINE> SYSTEM> CurrentControlSet> Control> Session Manager> Memory Management> DisablePagingExecutive

set to? 0 or 1?

[Just Learnin']

Set to 0 your fly is down,er, ah, JoeMan.

[joeMan]

Set it to 1, reboot then run the observation again over several hours as before. Please advise...beeeeeeeeeeeep.

End transmission.

[Just Learnin']

Have done beeeeeeeeeeeep! On boot was 221,800 k, *crud* within 5 minutes is at 242,076 k beeeeeeeeeeeeeeep. Oh yeah, what am I trying to accomplish here? For those of me totally unaware of the concept. :o

[joeMan]

Just seeing if maybe we can arrive at a setting where system cache doesn't get so large...why? Good question! LOL

[Just Learnin']

Well it's been over an hour now and system cache is at 1,383,296 k Riddle me this is that good or bad??

[joeMan]

No, it's not bad because if I understand correctly, those pages sitting there are pretty much the sum total of all the pages you've called for since last boot...they are sitting there for faster access in case called upon again. It's not to worry you because this number is NOT the same as available memory...available memory is the one that if it drops super low then get worried, but as long as available memory stays at a decent level then your number there in System Cache can reamin as large as it wants to be. Those system cache pages are not holding firmly to their place, they are perfectly willing to get kicked out of there as soon as something else of more priority (whatever apps you launch & use) needs to use the space.

This is my understanding of it all so far...hopefully it is correct information...maybe Ryder will jump in here again to verify this is correct, or set the record straight if I am wrong.

[Just Learnin']

Another 6 1/2 hours and it is down to 633,200 k . My daily virus scan has just spiked it back up to 1,750,000 k .

[Just Learnin']

1,722,700 k now, guess I'll switch the reg back to "START> Run> Regedit> HKEY_LOCAL_MACHINE> SYSTEM> CurrentControlSet> Control> Session Manager> Memory Management> DisablePagingExecutive" 0

Really not getting this excercise, is there a performance difference or or or?

[joeMan]

I was just trying to see if there were any combination of settings where the "System Cache" would not get to such a large number and then stay there JL. Personally I have always set DisablePagingExecutive=1, simply because the XP Tweakguide said so, and for the same reason as stated over at neoseeker. From neoseeker.com in an XP tweak article:


Disable Paging Executive
This will prevent pages sections from RAM going to the hard drive. If you have a large amount of RAM at least 256Mb (I suggest 512) you might want to keep the data in your RAM to improve your performance considerably due to reduced amount of hard drive swappage. The entry that you will want to modify is called DisablePagingExecutive. Changing this from 0 to 1 will keep the data in your RAM.

"DisablePagingExecutive"=dword:00000001

But this next one is the one that I thought was causing the "System Cache" number to grow and stay large, after Ryder brought it to my attention to check it:


System Cache Boost
The XP kernel can be loaded into your RAM with a simple registry edit. This can greatly improve performance since the NT Kernel will always be in your RAM. With this edit you will allocate roughly 4Mb of your RAM for the kernel. Sometimes more RAM is used but most of the time it is only 4Mb. The entry that you will need to find is called LargeSystemCache and you'll need to change this from 0 to 1 in order to enable this.

"LargeSystemCache"=dword:00000001

...so I did check and sure enough it WAS set to 1 on my daughters PC and that coincided with the performance options> advanced> memory usage in XP being set to "System Cache" rather than to "Programs". Once I switched the setting back to "Programs" and rebooted I verified that "LargeSystemCache" had indeed reset to 0. And, ever since switching it back to "programs" and/or "LargeSystemCache=0" (same thing apparently) - the large "System Cache" in task mgr ceased to exist growing large and staying large.

I assumed your experience would be the same, but apparently it is not. Your System Cache in task mgr seems to grow large and stay large irregardless of these tweaks we've been discussing.

[Just Learnin']

I am getting the feeling my machine thinks it is a server? :suspect: :coocoo:

[joeMan]

I am getting the feeling my machine thinks it is a server? :suspect: :coocoo:
:lol: :lol: yes... :coocoo: indeed. Sorry for the wild goose chase JL. Thanks for participating in the great DisablePagingExecutiveLargeSystemCacheWhichIsBetterForASmallerSystemCacheAtAnyGivenTime=1 experiment...

[Just Learnin']

Ummm.... Set it back to zero yesterday and this evening I noticed the System Cache is only 447,140 k . Is this looking "average" to anyone? :scratch: