High activity on HDD after wakeup from hibernation

GeneO · 18 Jun 2011

Britton30 said:

Unless you are using a Solid State Drive, Superfetch should be enabled. It keeps program bits and often accessed files in memory. This allows your PC to run and open your programs quicker.

I think even with and SSD it is good. Loading a program from RAM is instantaneous, since it is already in memory, and so is faster than loading it into RAM from an SSD.

GeneO · 18 Jun 2011

So I figure an explanation is in order. When you close a program, the program code and data is not removed from memory, but is kept in a stand-by state and may only used if more memory is needed by another program and there is no memory in the free state. Superfetch will run in the background and pre-load frequently used programs into memory in the stand-by state after you boot.

When you hibernate, the active memory is saved to disk, but not the stand-by. So you would loose your pre-loaded programs when you wake from hibernate. This is the Microsoft scenario that you leave for lunch, your computer hibernates, you return, and you wonder why it takes so long to load Word. To prevent this, superfetch runs in the background when you wake from hibernate.

kharl · 19 Jun 2011

Thank you guys!
For the advices, explanation, participation... thanks!

pooch · 19 Jun 2011

GeneO said:

I think even with and SSD it is good. Loading a program from RAM is instantaneous, since it is already in memory, and so is faster than loading it into RAM from an SSD.

Just to add my 2 cents to this. The difference between loading from RAM with Superfetch enabled and the time it takes to load from an SSD is minimal. I would recommend SSD users to try both and see what is best for them.

What is important and directly related to this thread is the use of Hibernation with a SSD. Hibernation causes a lot of unnecessary writes to a SSD and is in this scenario in my opinion, best switched off.

whs · 19 Jun 2011

The difference between loading from RAM with Superfetch enabled and the time it takes to load from an SSD is minimal

Well, make the computation. 256 bytes are read from RAM in a max. of 15 nanoseconds. For the SSD you already need 100 nanoseconds (0.1ms) on average to access the storage. To that you have to add the data transfer time. That makes RAM about 10 times faster than the SSD.

pooch · 19 Jun 2011

whs said:

The difference between loading from RAM with Superfetch enabled and the time it takes to load from an SSD is minimal

Well, make the computation. 256 bytes are read from RAM in a max. of 15 nanoseconds. For the SSD you already need 100 nanoseconds (0.1ms) on average to access the storage. To that you have to add the data transfer time. That makes RAM about 10 times faster than the SSD.

When you put it like that yes it is an awesome difference

In the real world it is hardly noticeable, what are a few nanoseconds between friends? lol

whs · 19 Jun 2011

That is of course true. But if you add up many small slowdowns that are not noticable individually, you may still have an impact in their sum.

pooch · 19 Jun 2011

whs said:

That is of course true. But if you add up many small slowdowns that are not noticable individually, you may still have an impact in their sum.

lol I am not going to argue the point

I live happily without Superfetch and its up to others users to decide what they prefer with there SSD's

whs · 19 Jun 2011

I always keep Superfetch on. But I have really never measured the difference - which would probably be difficult anyhow. I just trust the numbers.

GeneO · 19 Jun 2011

whs said:

That is of course true. But if you add up many small slowdowns that are not noticable individually, you may still have an impact in their sum.

To quote a friend from back when we were programming real-time data acquisitions systems: a microsecond here, a microsecond there, and pretty soon you have real time.

Well the OP wasn't about SSD anyhow. But you see all of the angst when someone is trying to decide which SSD to buy, this one is a few MB/s faster on random 4k writes, this one a little faster on... which should I buy - when it doesn't make a difference real world. But opening Photoshop from an SSD takes maybe a few seconds and only a second if it is pre-loaded in RAM. That is a difference.

I am not sure the prefetch part of superfetch does much good for speeding up boot time with an SSD though, from my limited understanding of what prefetch does. I will have to test it sometime.