I should have listened in maths at school

marque

It's come back to bite me on my ass, school has, well at least not listening in maths class.

I am using exec("ping -q -c 1 -s 8 $REMOTE_ADDR") to get the users ping.

Then I want to convert the ping into bytes per second, then KB/s etc.

Eventually I want to get the ETA download time on how long it will take to download a particular file.

Trouble is, I have no clue on how to do the math.

I'm sending out 8 bytes of data which translates into 16 ICMP bytes and it (after i clean it up) returns the milli-seconds it took to do the round trip.

I can figure out how long it will take not a problem, if I could get the correct bytes / second or even bytes / milli-second.

Anyone good at maths that can help?

DigitalExpl0it

hope this helps

// CHECK FILE SIZE
$filesize = filesize($partialPath.$slash_side.$entry);
if ($file_size >= 1073741824) {
       $filesize = number_format(($filesize / 1073741824),2) . " GB";
	    $filesize2 = "Big";
} elseif ($filesize >= 1048576) {
       $filesize = number_format(($filesize / 1048576),2) . " MB";
	    $filesize2 = "Big";
} elseif ($filesize >= 1024) {
       $filesize = number_format(($filesize / 1024),2) . " KB";
	   $filesize2 = "Small";
} elseif ($file_size >= 0) {
       $filesize = $filesize . " bytes";
	   $filesize2 = "Small";
} else {
       $filesize = "0 bytes";
	   $filesize2 = "Small";
}

marque

Yeah got that,

thats the easy part 🙁

I need the math to work out download speed: bytes per second

I have come to this sofar:

Lets say the ping takes 100 ms to do send and receive 16 bytes

That means it takes 6.25 ms to send and receive 1 byte.

Which equalates to 0.00625 seconds to send and receive 1 byte.

I need to find out how many bytes I can download in 1 second when 1 byte takes 0.00625 seconds to download.

matt_4013

You're going the wrong way 🙂

If I got this right (and it's highly possible I didn't :rolleyes🙂 you want this:

$bytesps = (1000/$pingtime) * $pingsize;

marque

I came to that figure before, 160 is the is the result of the ping size being 16 and the time being 100

(1000/100) * 16 = 160

160 bytes per second???

isn't that incredably slow considering the ping is 100 ms?

$bytesps = (1000/$pingtime) * $pingsize;
$kbps = round($bytesps / 1024,2);

gives 0.16 KB/s

matt_4013

Now that I actually think about your problem, I don't think that what you're trying to do will work. You're trying to work out the bandwidth from a ping, but bandwidth is not entirely dependant upon latency. I live in Australia, I ping up to 500ms on my adsl connection to US servers, yet still download at my maximum capacity. Also, on Dial-Up, I can ping 100 to a server, get the same ping from my broadband, and download at 10 times the speed. As such, I'm note entirely sure it will work the way you want it to. The mathematics I gave you is theoretically correct, I checked again to make sure, but the theory behind the actual values used in the calculation isn't right.

I think 😉

If I'm wrong, somebody correct me, I want to know!

marque

Thanks I was begining to suspect that, I too live in Australia, in Brisbane. My ping from my server on rackshack (US) to my bigpond cable account gives me +- 300 ms.

The results from your algorithm for me are:

ping time: 306.1 ms

3345.3119895459 Bytes/s
3.2669062397909 KB/s

with the ping being default (54 + 8) = 62.

However my average download from my server is around 18 - 24 kb/s.

It has been begining to confuse the crap out of me! I'm not one who likes to be told it can't be done, but I am willing to accept defeat on this one.

If anyone knows how or if this can work please let me know. I promise i will publish the completed function so everyone can show their users how long it will take to download a file.

Ahh a perfect world with accurate ETA's on all your downloadable files, can't you just picture it?