Diff.between "available" and "free" physical memory?

[pstein]

Diff.between "available" and "free" physical memory?

When I look into the "Performance" tab of my TaskManager then there are the following values:

Total: 4014
Cached: 1299
Available: 2697
Free: 1532

Hmm, What is the difference between available and free space?
Shouldn't this be the same?

What means cache?

From my point of view there should be a value "occupied by running prgms" and "free".

Peter

 

[logicearth]

Available is the only one that matters. Available shows what is capable of being used by Programs. Without paging other lower priority processes out of memory. It is a combination of both Cache and Free.

 

[Keiichi25]

Plus the current memory handling architecture for Win 7 is that it tries to front load possibly needed libraries into memory to help speed up things. The free part is basically the memory that doesn't have any front loaded material at all. For the most part, as Logicearth pointed out, Available is the one that you should trust more, as the frontloaded libraries are easily forgotten in favor of making room for needed memory.

 

[pparks1]

As others have said, Windows 7 will preload things into RAM when your computer isn't busy...this way when you do need or want them, they launch much faster.

In your chart above, the free (totally unused) + cache (that which has been preallocated) should just about equal the available amount. The available is going to show just a bit less than these two summed together.

In any instance that you need more RAM than what is Free...Windows 7 will just use the cached memory and dump what is there.

If you have the memory, might as well use it. It does no good if it sits there totally unused all day long.

 

[pbcopter]

This is a good article.

Measuring memory usage in Windows 7 | BrandonLive

 

[cdonner]

Important difference

Unfortunately there is a bug in Windows 7 related to NUMA (non-uniform memory architecture) that will cause issues on certain platforms when the amount of Free memory goes down. For instance, on my Thinkpad T410 with 8GB of RAM the Free memory will approach zero when I load a large VM. When I stop the VM and exit VMWare, the Free memory does not recover - the memory remains allocated by the cache.
The problem with NUMA is that it prefers to allocate memory from banks that are attached to a CPU core (hence non-uniform, i.e. not all memory is considered equal). Unfortunately, the Windows 7 NUMA bug prevents memory from being allocated that is in the Available pool in this scenario. Since I have no Free memory, the machine begins to swap madly when I restart the VM (the same or another one does not matter) and freezes up for minutes - even though there are over 4GB "Available".
So, despite of what the others have said, the amount of "Free" memory is more important than what's in the "Available" pool.

There is a hotfix for this issue:
Poor performance occurs on a computer that has NUMA-based processors and that is running Windows Server 2008 R2 or Windows 7 if a thread requests lots of memory that is within the first 4 GB of memory

 

[whs]

Look into Resource Monitor > Memory tab. That gives you a better picture. The nums in Task Manager can be confusing. Everything you see in blue, is up for grabs by more programs/processes/data. The orange is temporary and still needs to be written back to disk, the green are your running process/data and the grey is hardware reserved (e.g. for graphics).

 

[IWonderif]

When I look into the "Performance" tab of my TaskManager then there are the following values:

Total: 3987
Cached: 2305
Available: 2652
Free: 395

Are these values normal?

 

[whs]

When I look into the "Performance" tab of my TaskManager then there are the following values:

Total: 3987
Cached: 2305
Available: 2652
Free: 395

Are these values normal?

Looks normal to me. You must have been running a lot of programs since the system was booted. That's why the 'cached' is relatively high - but that's OK. You might as well make use of all the RAM. 100% usage of the RAM is the best case.

 

[bobafetthotmail]

the "cached" just means "RAM with stuff in it that can be freed if needed", your numbers look fine.

 

[JimmyTryhard]

Guys... I believe I have a problem:
Total: 4024
Cached: 1721
Available: 1664
Free: 1

Recently I have been having "MEMORY_MANAGEMENT" Bluescreens while gaming or using many tabs on Firefox... is this the reason? I always seem to have 0 - 160~ in the Free category and performance has become sluggish lately. Should I buy new RAM or should I just flat out replace it? Like I said, I have been having MEMORY_MANAGEMENT BSODs and I think this is the reason. I am thinking about buying another 4 GB of RAM for my system. Good idea? please help.

P.S. I am running 1333 Mhz RAM btw.

 

[whs]

Where are you getting these numbers from. Look into Resource Monitor > Memory tab. The colored bar will give you the full story.

 

[JimmyTryhard]

i was looking at task manager. But even in resource monitor it has limited free ram.

 

[JimmyTryhard]

But wait, that doesnt matter right? only "available" matters right?

 

[whs]

The 'Standby' and 'Free' in Resource Monitor are both 'available'. The standby is RAM where previously run programs are cached. The OS fetches the program from there in case you use it again. That is the fastest access possible. But that RAM will be used if a new program needs the space.

So you have to add the 2 blue areas together to obtain available RAM.

 

[logicearth]

Recently I have been having "MEMORY_MANAGEMENT" Bluescreens while gaming or using many tabs on Firefox... is this the reason?...

The reason is not because lack of RAM. Running out of RAM does not cause a blue screen. Instead it could be an error in the system, for example bad memory.

 

[kbrady1979]

For monitoring system resources, I find Resource Monitor better than Task Manager........Click Start > type Resource Monitor and there it is. It may make things a little easier to understand.

 

[LMiller7]

Memory management in Windows is complex and follows principles that are not obvious and may at times seem to make no sense. But there is method in the apparent madness.

Free memory: This is memory that contains no useful data. It is expensive fast memory just sitting there, consuming power and providing nothing in return. You don't want it and you don't need it. The only good thing about it is that it can immediately be taken out of unemployment and set to work. The ideal would be for free memory to be zero at all times but we aren't there yet.

Available memory: This is the sum of memory on the free list (bad), and the standby list (good). Memory on the standby list can also be immediately be put to work for any application. But what sets it apart from free memory is that it contains useful data and code, it just hasn't been recently used. This memory serves a dual role. As mentioned it can be given to any application. In addition, as it still contains the original code or data it can be given back to the original application it belonged to. In the resource manager of Vista and later you can see the values for free and standby memory. The value for standby memory should be high and free as small as possible. Standby memory also exists in XP but it takes some sophisticated tools to see it's value.

Cache memory: This is the sum of the file cache and the standby list. The file cache contains a copy of file data that has been recently accessed. If it is needed again, as often happens, it can be more quickly read from RAM than from disk. The file cache and the standby memory are both a form cache so it makes sense to show them together. A high value is a good thing. If an application needs more memory the size of the file cache will be trimmed if necessary.

Please note that the above is a highly simplified description of what is really a very complex process. The system memory manager will always try to assign memory where it will do the most good, and keep the unemployed free memory as low as possible.

 

[ViSco]

Unfortunately there is a bug in Windows 7 related to NUMA (non-uniform memory architecture) that will cause issues on certain platforms when the amount of Free memory goes down. For instance, on my Thinkpad T410 with 8GB of RAM the Free memory will approach zero when I load a large VM. When I stop the VM and exit VMWare, the Free memory does not recover - the memory remains allocated by the cache.
The problem with NUMA is that it prefers to allocate memory from banks that are attached to a CPU core (hence non-uniform, i.e. not all memory is considered equal). Unfortunately, the Windows 7 NUMA bug prevents memory from being allocated that is in the Available pool in this scenario. Since I have no Free memory, the machine begins to swap madly when I restart the VM (the same or another one does not matter) and freezes up for minutes - even though there are over 4GB "Available".
So, despite of what the others have said, the amount of "Free" memory is more important than what's in the "Available" pool.
There is a hotfix for this issue:
Poor performance occurs on a computer that has NUMA-based processors and that is running Windows Server 2008 R2 or Windows 7 if a thread requests lots of memory that is within the first 4 GB of memory

Hi cdonner and all,
I don't know if you're still there after 2 years from this post .....
I have a Thinkpad T410 with Win7 64bit 5GB RAM and the same issue with virtual machines, both VirtualBox and VMWare Player, lot of available memory but VMs not starting with diagnostic reporting not enough memory.
3GB available memory and VM configured for 512MB RAM.
All was perfectly working on the same PC when it was WinXP with even less RAM (3GB).
Is there any news from this front?
I have a corporate PC and I cannot install hotfixes
I wonder if after 2 years Win7 has not yet resolved this kind of issue?
Hope to find some help, I really need to run VMs.
Thanks in advance
ViSco

 

[Richman1]

The ideal would be for free memory to be zero at all times but we aren't there yet.

A high value is a good thing. If an application needs more memory the size of the file cache will be trimmed if necessary.

Well, I have Windows 7 64bit and 4GB of RAM 512MB being used by on board Radeon and often have FREE memory around 15-20 and sometimes single digits but what I can' figure out (if anyone can shed some light on this) is why if I have anywhere from about 900MB -over 1GB, like 1200MB or so, I am getting constant 'Out of Memory' warnings while running Google Chrome and also the old 'Low memory' Telling my I should close 'The Program' and then it usually list 'Google Chrome' or 'Desktop Gadgets' or some offending, memory hogging program. I don't see why it would warn me I am running out of memory consider I still have around or close to 30% of the memory still available.

This problem has driven me crazy ever since I have installed Windows.