Functions to get current CPU load and memory usage under Windows and Linux.

help.php

https://www.php.net/manual/en/function.sys-getloadavg.php#118673


Function to get current CPU load as percentage value under Windows and Linux.

Note: Function is getServerLoad(). It will return a decimal value as percentage of current CPU load or NULL if something went wrong (e. g. insufficient access rights).

<?php

    header("Content-Type: text/plain");

    function _getServerLoadLinuxData()
    {
        if (is_readable("/proc/stat"))
        {
            $stats = @file_get_contents("/proc/stat");

            if ($stats !== false)
            {
                // Remove double spaces to make it easier to extract values with explode()
                $stats = preg_replace("/[[:blank:]]+/", " ", $stats);

                // Separate lines
                $stats = str_replace(array("\r\n", "\n\r", "\r"), "\n", $stats);
                $stats = explode("\n", $stats);

                // Separate values and find line for main CPU load
                foreach ($stats as $statLine)
                {
                    $statLineData = explode(" ", trim($statLine));

                    // Found!
                    if
                    (
                        (count($statLineData) >= 5) &&
                        ($statLineData[0] == "cpu")
                    )
                    {
                        return array(
                            $statLineData[1],
                            $statLineData[2],
                            $statLineData[3],
                            $statLineData[4],
                        );
                    }
                }
            }
        }

        return null;
    }

    // Returns server load in percent (just number, without percent sign)
    function getServerLoad()
    {
        $load = null;

        if (stristr(PHP_OS, "win"))
        {
            $cmd = "wmic cpu get loadpercentage /all";
            @exec($cmd, $output);

            if ($output)
            {
                foreach ($output as $line)
                {
                    if ($line && preg_match("/^[0-9]+\$/", $line))
                    {
                        $load = $line;
                        break;
                    }
                }
            }
        }
        else
        {
            if (is_readable("/proc/stat"))
            {
                // Collect 2 samples - each with 1 second period
                // See: https://de.wikipedia.org/wiki/Load#Der_Load_Average_auf_Unix-Systemen
                $statData1 = _getServerLoadLinuxData();
                sleep(1);
                $statData2 = _getServerLoadLinuxData();

                if
                (
                    (!is_null($statData1)) &&
                    (!is_null($statData2))
                )
                {
                    // Get difference
                    $statData2[0] -= $statData1[0];
                    $statData2[1] -= $statData1[1];
                    $statData2[2] -= $statData1[2];
                    $statData2[3] -= $statData1[3];

                    // Sum up the 4 values for User, Nice, System and Idle and calculate
                    // the percentage of idle time (which is part of the 4 values!)
                    $cpuTime = $statData2[0] + $statData2[1] + $statData2[2] + $statData2[3];

                    // Invert percentage to get CPU time, not idle time
                    $load = 100 - ($statData2[3] * 100 / $cpuTime);
                }
            }
        }

        return $load;
    }

    //----------------------------

    $cpuLoad = getServerLoad();
    if (is_null($cpuLoad)) {
        echo "CPU load not estimateable (maybe too old Windows or missing rights at Linux or Windows)";
    }
    else {
        echo $cpuLoad . "%";
    }

?>

test.php

memory_get_usage() is used to retrieve the memory allocated to PHP only (or your running script). But intuitively, many people expect to get the memory usage of the system, based on the name of the function.

So if you need the overall memory usage, following function might be helpful. If retrieves the memory usage either in percent (without the percent sign) or in bytes by returning an array with free and overall memory of your system. Tested with Windows (7) and Linux (on an Raspberry Pi 2):

<?php

    // Returns used memory (either in percent (without percent sign) or free and overall in bytes)
    function getServerMemoryUsage($getPercentage=true)
    {
        $memoryTotal = null;
        $memoryFree = null;

        if (stristr(PHP_OS, "win")) {
            // Get total physical memory (this is in bytes)
            $cmd = "wmic ComputerSystem get TotalPhysicalMemory";
            @exec($cmd, $outputTotalPhysicalMemory);

            // Get free physical memory (this is in kibibytes!)
            $cmd = "wmic OS get FreePhysicalMemory";
            @exec($cmd, $outputFreePhysicalMemory);

            if ($outputTotalPhysicalMemory && $outputFreePhysicalMemory) {
                // Find total value
                foreach ($outputTotalPhysicalMemory as $line) {
                    if ($line && preg_match("/^[0-9]+\$/", $line)) {
                        $memoryTotal = $line;
                        break;
                    }
                }

                // Find free value
                foreach ($outputFreePhysicalMemory as $line) {
                    if ($line && preg_match("/^[0-9]+\$/", $line)) {
                        $memoryFree = $line;
                        $memoryFree *= 1024;  // convert from kibibytes to bytes
                        break;
                    }
                }
            }
        }
        else
        {
            if (is_readable("/proc/meminfo"))
            {
                $stats = @file_get_contents("/proc/meminfo");

                if ($stats !== false) {
                    // Separate lines
                    $stats = str_replace(array("\r\n", "\n\r", "\r"), "\n", $stats);
                    $stats = explode("\n", $stats);

                    // Separate values and find correct lines for total and free mem
                    foreach ($stats as $statLine) {
                        $statLineData = explode(":", trim($statLine));

                        //
                        // Extract size (TODO: It seems that (at least) the two values for total and free memory have the unit "kB" always. Is this correct?
                        //

                        // Total memory
                        if (count($statLineData) == 2 && trim($statLineData[0]) == "MemTotal") {
                            $memoryTotal = trim($statLineData[1]);
                            $memoryTotal = explode(" ", $memoryTotal);
                            $memoryTotal = $memoryTotal[0];
                            $memoryTotal *= 1024;  // convert from kibibytes to bytes
                        }

                        // Free memory
                        if (count($statLineData) == 2 && trim($statLineData[0]) == "MemFree") {
                            $memoryFree = trim($statLineData[1]);
                            $memoryFree = explode(" ", $memoryFree);
                            $memoryFree = $memoryFree[0];
                            $memoryFree *= 1024;  // convert from kibibytes to bytes
                        }
                    }
                }
            }
        }

        if (is_null($memoryTotal) || is_null($memoryFree)) {
            return null;
        } else {
            if ($getPercentage) {
                return (100 - ($memoryFree * 100 / $memoryTotal));
            } else {
                return array(
                    "total" => $memoryTotal,
                    "free" => $memoryFree,
                );
            }
        }
    }

    function getNiceFileSize($bytes, $binaryPrefix=true) {
        if ($binaryPrefix) {
            $unit=array('B','KiB','MiB','GiB','TiB','PiB');
            if ($bytes==0) return '0 ' . $unit[0];
            return @round($bytes/pow(1024,($i=floor(log($bytes,1024)))),2) .' '. (isset($unit[$i]) ? $unit[$i] : 'B');
        } else {
            $unit=array('B','KB','MB','GB','TB','PB');
            if ($bytes==0) return '0 ' . $unit[0];
            return @round($bytes/pow(1000,($i=floor(log($bytes,1000)))),2) .' '. (isset($unit[$i]) ? $unit[$i] : 'B');
        }
    }

    // Memory usage: 4.55 GiB / 23.91 GiB (19.013557664178%)
    $memUsage = getServerMemoryUsage(false);
    echo sprintf("Memory usage: %s / %s (%s%%)",
        getNiceFileSize($memUsage["total"] - $memUsage["free"]),
        getNiceFileSize($memUsage["total"]),
        getServerMemoryUsage(true)
    );

?>

The function getNiceFileSize() is not required. Just used to shorten size in bytes.

Note: If you need the server load (CPU usage), I wrote a nice function to get that too: http://php.net/manual/en/function.sys-getloadavg.php#118673