Maximum PC

Hello All! I'd love to see Maximum PC take a page in the mag to cover this topic, though I know there are so many variables it's probably tough. Still, a general rule of thumb chart and some hard facts would be nice. There's a lot of info out there on the web, and much of it is clearly from people who are regurgitating bad info passed on to them.

Anyway, I just built a new z68 system w/ a 2600k and 16GB of RAM. I also purchased two 64GB SSD's @ 6GBPS which I've striped in RAID 0 and have my OS installed on. (Yes, it's fast ) I've moved all of my data folders to a data drive but in this day and age 128GB doesn't stretch all that far, so I'm trying to really keep c: as clean as possible. (infrequently used programs that I don't care too much about performance are being installed on the data drive as well)

I've got a good amount of power, speed and RAM and am looking to optimize where I can. I realize that removing the page file entirely is a poor idea, but what should I set it at? Windows has seen fit to match it to my physical memory so my page file is about 16gb, and my hyberfil.sys a cool 12gb. I used to be a big proponent of and equal to or greater than page file, but is that really necessary with 16gb of physical RAM? Those two files alone are using almost 20% of my total space.


PS - I wasn't sure if this should be in free clinic or here. Seems more of a windows discussion, useful to many so I chose the parlor.

EDIT: Windows 7 Home Premium, 64-bit.

I have no idea why removing the page file entirely is a bad idea. With +6G physical memory, the space used for SSD's is more critical IMO. I am all SSD (But the WHS), all +6G memory, and all of those have no page file and work fine. You can leave it enabled (Lock it at 1024 min/max) and never see it get used with these amounts of physical memories to utilize. It's a good Blanket statement to say "use it" because Granny may have 1G physical memory, onboard graphics that use memory, and all that...but for the MPC crew that is up to date on tech, I say ditch it.

You've got to understand what virtual memory is. It's when you run out of physical memory and then start to use the hard disk's fake memory for storage. With spindle drives, you instantly KNOW when you hit it because it's a real drag. But if some program sucks up 6G or more of your milkshake to get to that point of using the VM, something is horribly wrong. Seems logical, right?

Another aspect to this is the automatic setting and SSD's. It will grow and shrink as Windows sees fit, and that's exactly what you don't want on an SSD. Growing and contracting is pretty much the same as defragging. It's just un-needed writes to the drive. In the very least, set it to a static size.

Disable it, give it a run, and find fault with it.
If you need a firm size, set it to 3072 min/max and lose 3G that may never get hit. But it won't grow and shrink.

Ahem... the hard disk's fake memory?


Well, if you're doing any kind of 'real computation' with a computer, there is a good chance that you'll be dealing with data sets that are much larger than just 6GB, right? I wouldn't be too quick to disable it just because Murphy's Law dictates that you'll actually run out of memory at the worst possible time. Of course, if your primary PC usage is games, video and Facebook, then who really cares. *

Also, it isn't a single program using the VM, but all programs (processes, actually) including the OS (which doesn't really work the way most people think it does). Virtual memory is actually a bit more complex then just writing to secondary memory when you've run out of primary memory.

* Writing/thinking out loud here... what happens if you disable the VM, the OS crashes, and the computer reboots only to find out that the OS and 'start up' programs actually exceed the physical memory on the system? Does Windows automatically enable the page file during a safe mode boot? That could be an interesting problem to have... =)

eh...I'm from the school that one would be better served setting up a RAM drive and sticking the page file there.

I guess in a perfect world, one could say disable it.If devs were perfect though, we wouldn't have things like memory leaks or apps that run the system out of memory, so there is a need for page file.



There is such a thing as the minimum system requirements

In the days of multi-terabyte drives, are you really that pressed for space you can't afford [(Physical Ram) * 1.5] GB of disk space for a page file? You aren't running a secondary hard drive for data? (If you aren't shame on you... one might think you are TRYING to shorten the lifespan of your SSDs).

Paging is going to happen no matter what and some applications are written with that in mind. I would recommend against turning it off. Especially since it has to happen anyway.

WIth 16 GB of ram you'd probably be okay, but there will be that one application that won't work right without it. I know that Photoshop etc has a "scratch" file which is very similar to the page file but managed by the application. So long as the app is written like that, turning off the page should be fine.

In your situation though you really should have another standard drive available to you for holding your data and you can put the page file there. 1.5x the physical ram might not be required. You could probably get away with 0.5x and be fine. I am not sure I recommend turning it off entirely.

I think that it's a myth that you need 1.5*ram for your pagefile, especially for regular users who probably won't run out of 16gb or ram (99% of all users in my book). I believe that in general, the more memory you have, the smaller your pagefile can be. However, I would say you don't want it to be too small (4gb+). You certainly don't want to completely throw away the pagefile.

Completely disabling the pagefile is a bad idea. I would say that you would be fine with either a 4gb or 8gb pagefile, and you could probably just stick it on your data drive and not see any difference. The only reason that I could think of not to stick it on the data drive is if you allow Windows to spin down the data drive to save power. Putting the pagefile on it would need to constantly read/write to/from it, and wouldn't allow it to spin down.

Unless you hibernate your computer often, I would also stick the hibefile on your data drive, because that may eventually grow to 16gb (basically writes your memory to the HDD when you hibernate, and reads HDD back into memory upon resume). Personally, I would do a test. Try it on both the SSDs and the data drive. Time how long it takes to hibernate, and resume, and then make a decision based on the information you collect, and your personal preference. (The same can be done for the pagefile too), although unless you regularly use more than 16gb, you won't notice any difference in performance.

It's not really a myth because at one time it was a true statement. That time was...pre-windows xp.

As with most info out there though, the statement needs to be updated with the times, and I'm not sure I've ever seen anything out there that tells me what to do or not to do with a page file considering that we're now at 64 bit addressing

lols pre-windows xp. That was before some people on this forum were even born ok...maybe not that old, but still....

There seems to be quite a bit of confusion regarding the implementation and use of virtual memory and paging.


VM isn't really meant to protect you against faulty programs though I guess it could help in the case that you described. It really is a FEATURE! If someone were to give you a 100GB data set and ask you to perform some operation that couldn't be distributed or sequenced in some manner, you're going to be glad that you have VM.


Yeah, it was really meant to be more of a theoretical possibility... =)

Stop the press... darn business app programmers... =)

How can an application be written with the page file in mind? It is a HW mechanism: If a page fault occurs, which is a HW interrupt, the MMU responds by retrieving the appropriate page (which depends heavily on the type of HW involved... LBA, indexed memory, etc). You can't really write a program to take advantage of VM (though I suppose you could write a really bad program that causes unnecessary paging). Even the OS can't really do too much aside from following along with what the HW engineers intended.

Now an application that creates it's own swap/page file is a completely different story... =)

It sort of pleases me to see that even here at Maximum PC this is a misunderstood subject with seemingly uninformed answers and assumptions, however logical they may be (not intended to be snide). Maybe MPC really should write an article on the matter as more and more of us find ourselves with massive amounts of memory, and fast, but small SSD's where this becomes a concern.

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The reason I noted that I'm not going to disable it entirely, is that it's my understanding that some applications are simply written to access it and run poorly, or not at all without it. I'm not sure what programs these are specifically, but I know on a system I disabled the pagefile on a while back, I encountered an out of memory error that was absurd and had to have been the lack of a pagefile as I had gigs free.

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In the past I've always written the page file to a separate, equally fast drive and disabled it on my system drive. The reason I'm now curious as it seems silly to write the file to a considerably slower location..but that too is just based on assumption. Would it be perfectly fine here?

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So with regard to the last post and a successful memory dump - how does that effect me? (asked in the tone of a serious question, not a smart-ass retort ) I've always thought of Memory dumps as being useful in debugging and troubleshooting at a very, very technical level, etc..is there more to the story? Is there any reason why I need a complete dump of the physical memory on my personal system? Being a guy that's never accessed a dump file, I'm not 100% clear on this aspect of what it is and why I'd need it. Maybe my entire concept of a memory dump is looking from the wrong angle

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Thanks all for the replies, apologies for the delays in responding, I was out of town.

No, not a myth. Perfectly valid standard practice. Most users don't have 16 GB of ram. Most don't even have 8 GB of ram. 3 and 4 GB is still VERY common/standard. In that case, 1.5xPhysical is still perfectly valid. You are correct though no page file is bad. I would say that in today's world for most people, 1x is about right.

It was very valid in XP and Vista even. It is less so today... but with hard drive space so available does it really matter? Also I am sure it still remains pretty true in the server environment.

I would agree with that although my statement wasn't solely about what OS we were using at the time. I think we both know that this 1.5 deal has been around since 95/NT. To be clear, I chose XP because of the shift in these things...yea..HDs became bigger, RAM more readily available...and you're right with TB drives at 8 Gigs of RAM on one's machine...why sweat this.

I seem to remember the big issue then wasn't so much disk space, but just windows ability to open large files to include the page files. Even in XP with 4 gigs and a large HD, I'm not so sure I'm even sweating what the heck my page file is doing.

in light of the question "why sweat this", I guess I should morph the question.

Does having the page file on a considerably slower drive degrade performance? Right now it's eating an awfully large percentage of the space on my 128gb RAID 0, 6gbps SSD boot array. If I move it to the good old 2TB 7200RPM 3gbps drive, am I kicking my own self in the pills?

If not then it's no big deal at all. If there is a performance hit, do I really nearly 20GB dedicated to the page file on the system drive?

Thanks

How is the OS controlled page file a hardware thing? Paging is up to the OS my friend, hence why Windows and Unix have two very different takes on paging and "swap" space.

I'd further like to know if I have 6 GB of physical ram why would I see 2.5 GB ram used and a 2.5 GB page file? Shouldn't the hardware know better? That there is plenty of ram space free?

Agreed. Gotta speak to the LCD though, we know it has been kind of a best practice/standard for a while. Not everybody might though. I don't think we are to the point where the LCD can turn off the page file. Psymonkey might be able to, but I can't say for sure.

Will it be slower? Sure, are you going to notice it? No way. When a page fault occurs things are already going to be put in a holding pattern because the memory page has to be retrieved from disk and loaded into physical memory (and likely something else has to be paged out).

Try turning it off and see what happens?

am I reading what you did wrong, or did you mis-read me? I was just simply stating that I have no idea why this topic even comes up all today..

No sir! =)

Yes, it is true that different OSes having different page file implementations. It is also true that memory systems require both hardware and software, but I will still argue that memory systems are truly about the hardware. Why? First, memory operations must absolutely be done as quickly as possible in order to have a fast computer. The MMU (HW) contains and is responsible for the TLB, memory protection, address translation and occasionally the page replacement algorithm. All cache operations are also done in HW. Second, the type of memory system(s) that can be implemented by an OS is actually determined by the HW. You can't implement a VM system on HW that doesn't support it (you'd have an emulator if you did). Third, the OS has to implement the interface defined by the hardware. If the OS implementation doesn't follow the HW/SW interface then address translation, the TLB, memory protection and several other aspects of a VM system aren't going to work. The OS is responsible for the page replacement algorithm, handling page fault exceptions, pinning memory (so that it can't be paged) and loading programs into memory (ie the loader). The OS certainly has a role to play, but that role is defined by the HW.

Don't make me break out my old AMD processor manuals and/or H&P book. =)


Was this intended for me? If not, I'd like to answer anyways because I think this is a good question.

The answer is speed. Some of the pages in memory will have not been modified after they were loaded or since last paged in from VM. The MMU/OS tracks whether a page has been modified (via the dirty bit). When a page needs to be removed from memory, it is generally preferable to remove one of these unmodified pages because you don't need to update the page file -- you can simply write over the current page in memory. This obviously has to be tracked before you exceed the physical memory capacity of the system, so yes, the hardware does know better.

Do I get the full marks for my answer? =)

I should probably start another thread for this question, but...

Is anyone using ReadyBoost? I'm thinking about using it with my Windows Vista laptop, but I want to get some idea of how it has worked out for people before bothering with it.

There was a benchmark a while ago, I can't recall the source but with 4 gigs of RAM it actually made the system a tad slower. It's a cheap and worthwhile upgrade if you have 2 gigs, but as you well know a flash drive is a lot slower than system memory.