SUSE/saptune

package note

import (
    "github.com/SUSE/saptune/system"
    "math"
    "strconv"
)

// section [mem]

// GetMemVal initialise the shared memory structure with the current
// system settings
func GetMemVal(key string) string {
    var val string
    switch key {
    case "VSZ_TMPFS_PERCENT", "ShmFileSystemSizeMB":
        // Find out size of SHM
        mount, found := system.ParseProcMounts().GetByMountPoint("/dev/shm")
        if found {
            val = strconv.FormatUint(mount.GetFileSystemSizeMB(), 10)
            system.InfoLog("GetMemVal - GetFileSystemSizeMB returned '%+v', converted to '%+v'\n", mount.GetFileSystemSizeMB(), val)
            if key == "VSZ_TMPFS_PERCENT" {
                // rounded value
                percent := math.Floor(float64(mount.GetFileSystemSizeMB())*100/float64(system.GetTotalMemSizeMB()) + 0.5)
                val = strconv.FormatFloat(percent, 'f', -1, 64)
                system.InfoLog("GetMemVal - GetFileSystemSizeMB returned '%+v', GetTotalMemSizeMB returned '%+v', percent is '%+v', converted to '%+v'\n", mount.GetFileSystemSizeMB(), system.GetTotalMemSizeMB(), percent, val)
            }
        } else {
            system.WarningLog("GetMemVal: failed to find /dev/shm mount point")
            val = "-1"
        }
    }
    return val
}

// OptMemVal optimises the shared memory structure with the settings
// from the configuration file or with a calculation
func OptMemVal(key, actval, cfgval, tmpfspercent string) string {
    // tmpfspercent value of VSZ_TMPFS_PERCENT from config or override file
    var size uint64
    var ret string

    switch key {
    case "VSZ_TMPFS_PERCENT":
        ret = cfgval
    case "ShmFileSystemSizeMB":
        if actval == "-1" {
            system.WarningLog("OptMemVal: /dev/shm is not a valid mount point, will not calculate its optimal size.")
            ret = "-1"
        } else if cfgval != "0" {
            ret = cfgval
        } else {
            if tmpfspercent == "0" {
                // Calculate optimal SHM size (TotalMemSizeMB*75/100) (SAP-Note 941735)
                size = uint64(system.GetTotalMemSizeMB()) * 75 / 100
                system.InfoLog("OptMemVal - tmpfspercent is '%s', GetTotalMemSizeMB returned '%+v', size is '%+v'\n", tmpfspercent, system.GetTotalMemSizeMB(), size)
            } else {
                // Calculate optimal SHM size (TotalMemSizeMB*VSZ_TMPFS_PERCENT/100)
                val, _ := strconv.ParseUint(tmpfspercent, 10, 64)
                size = uint64(system.GetTotalMemSizeMB()) * val / 100
                system.InfoLog("OptMemVal - tmpfspercent is '%s', converted to '%+v', GetTotalMemSizeMB returned '%+v', size is '%+v'\n", tmpfspercent, val, system.GetTotalMemSizeMB(), size)
            }
            ret = strconv.FormatUint(size, 10)
            system.InfoLog("OptMemVal - returns converted size as '%+v'\n", ret)
        }
    }
    return ret
}

// SetMemVal applies the settings to the system
func SetMemVal(key, value string) error {
    var err error
    var val uint64
    switch key {
    case "ShmFileSystemSizeMB":
        val, err = strconv.ParseUint(value, 10, 64)
        if val > 0 {
            if err = system.RemountSHM(uint64(val)); err != nil {
                system.ErrorLog("Resizing /dev/shm failed - '%+v'", err)
                return err
            }
        } else {
            system.WarningLog("SetMemVal: /dev/shm is not a valid mount point, will not adjust its size.")
        }
    }
    return err
}