Solved Displayed memory usage error in WebUI

[albinoman887]

It's not that simple, as I don't store it anywhere, it's directly manipulated as a float, and sent as text to the web page:

                        sprintf(result,"%.2f",(sys.totalswap * sys.mem_unit / (float)MBYTES));

The original bug was that the value wasn't multiplied by the unit size value (in your test, multiplying both values would give you 5 GB). If it still has issues reporting large values, then it's something else causing the whole calculation to fail (and it would be specific to ARM, as I couldn't reproduce the issue on a test case compiled for x86).

its just cosmetic anyways right?

 

[ColinTaylor]

its just cosmetic anyways right?

Correct.

 

[ColinTaylor]

It's not that simple, as I don't store it anywhere, it's directly manipulated as a float, and sent as text to the web page:

                        sprintf(result,"%.2f",(sys.totalswap * sys.mem_unit / (float)MBYTES));

The original bug was that the value wasn't multiplied by the unit size value (in your test, multiplying both values would give you 5 GB). If it still has issues reporting large values, then it's something else causing the whole calculation to fail (and it would be specific to ARM, as I couldn't reproduce the issue on a test case compiled for x86).

I don't think the calculation is failing as such. I don't know how that code works internally but there's obviously some sort of unsigned 32-bit precision in play. I don't think it's the sprintf statement so I'm assuming that sys.totalswap * sys.mem_unit is a 32-bit integer calculation.

I created a swap file that was exactly 7GB (#1C0000000 bytes) in size, so the 31st, 32nd and 33rd bits are set.

# free
             total       used       free     shared    buffers     cached
Mem:        934032     906284      27748       2396        464     557856
-/+ buffers/cache:     347964     586068
Swap:      7340032          0    7340032

# ./test-swap
unit_size: 4096 - total swap: 1835008

When viewed in the GUI it shows as 3072.00MB, or #C0000000 bytes. So something is truncating the value to an unsigned 32-bit number.