Author Topic: Virtualaddresslimit and Disk Free space, Questions  (Read 260 times)

roberto

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Virtualaddresslimit and Disk Free space, Questions
« on: November 07, 2018, 04:49:06 pm »
The first question is about the virtualaddresslimit, if I have a computer that the xcenter shows me 3430mb free when start,
and the pmview tells me that I have 3511mb, why can not I say a value in the config.sys higher than 3072mb?
Could it change after starting?


The other question is the free space on disk, according to the program you run shows me very different values, which is the correct one? , if any is right?
With rexx:
'Disk='SysDriveInfo('d:')
show               free                          total
Disk=D:  389265612800 524237774848 DATS

With chkdsk:
chkdsk show disk space is       511 999 548K
but space available                   380 143 256K -389 265 612K = 9,12 GB dif.!!!!

With DFSEE show:
Bitmap sect range : 0x3D0780D0 =  499952 MiB  Freesp : 0x2D5104F0 =  371232 MiB
        ┌────────────────────────────────────────────────────────────────┐     
00000000│▓█▓▓▓▓▓▓▓▓▓▓▓▓▓▒▓·                                             ·│ 25% 
        └────────────────────────────────────────────────────────────────┘     
Total / Used size : 0x3D08FC78 =  499999 MiB / 0x0FB6FB10 =  128735 MiB  25.7% 

SysDriveInfo       -          Dfsee
389 265 612 800 - 371 232 000 000=18 033 612 800   18,03 gb dif.

Something seems not right?
saludos

Dave Yeo

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Re: Virtualaddresslimit and Disk Free space, Questions
« Reply #1 on: November 07, 2018, 05:05:04 pm »
Virtualaddresslimit is the amount of virtual address space available to a program out of the 4GBs that our processors support. Some of the address space is used by the kernel and devices such as video memory, which is why the max is 3072 and is lower on some systems (to be stable). This is different from the amount of ram you have installed as it is virtual and can exist in your swap file or even as unallocated memory. As well different processes use the same virtual addresses in some cases.
eg you could have only 512 MBs of ram and have 2 programs using 1 GB of memory. Lots of swapping but the programs would each see that they have access to a GB.

There are different ways to measure disk space (and ram etc), some use a MB to mean 1,000,000 bytes as this makes a hard disk look bigger and some use a MB to mean 1,048,576 bytes. Now some (Dfsee) use MiB to mean 1,048,576 bytes and MB to mean 1,000,000 bytes.
Basically the marketers have changed the original meaning of MB as 1,048,576 to 1,000,000 to inflate sizes of HDs etc.

roberto

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Re: Virtualaddresslimit and Disk Free space, Questions
« Reply #2 on: November 07, 2018, 07:57:27 pm »
Thanks, Dave
In conclusion with the sysdriveinfo, I will have to multiply it by 0.95367488223 approximate average, to know the real value closest to reality.

Remy

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Re: Virtualaddresslimit and Disk Free space, Questions
« Reply #3 on: November 09, 2018, 12:33:55 am »
All disk (new) have a size base on official unit base on a classic mathemat value  1000 B for 1 KB and so on... (like 1 Kg etc...)
At origin due to binary mode, 1 KB was 1024 bytes and then it was renamed to KiB for kilo binary bytes and so on (both can be used but to have a bigger value and space on a disk, it is more interesting to use MB or GB instead of MiB or GiB as DAve wrote, marketing) 

1 GiB = 1024 MiB = 1024 x 1024 KiB = 1024 x 1024 x 1024 Bytes
1 GiB = 1024 MiB =  1,048,576 KiB = 1,073,741,824 Bytes

Why 1024 ?
binary >  1024 - 512 - 256 - 128 - 64 - 32 - 16 - 8 - 4 - 2 - 1

   

André Heldoorn

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Re: Virtualaddresslimit and Disk Free space, Questions
« Reply #4 on: November 09, 2018, 02:38:06 pm »
1 KB was 1024 bytes and then it was renamed to KiB for kilo binary bytes

FWIW: https://en.wikipedia.org/wiki/Kibibyte. A "new" standard, so perhaps a few authors have to insert that ï".

André Heldoorn

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Re: Virtualaddresslimit and Disk Free space, Questions
« Reply #5 on: November 09, 2018, 02:51:50 pm »
'Disk='SysDriveInfo('d:')
389265612800

With chkdsk:
but space available                   380 143 256K

With DFSEE show:
Freesp : 0x2D5104F0 =  371232 MiB

FWIW and rounded down. All numbers divided by 1024 until the result is less than 1024, so the final unit is the same:

389265612800 / (1024 * 1024 * 1024) = 362.53 units
380143256 / (1024 * 1024) = 362.53 units
371232 / 1024 = 362.53 units