xenperf: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/lib/xen-4.4/bin/xenperf - from package: xen-utils-4.4
/usr/sbin/xenperf - from package: xen-utils-common

You may install the required package with command apt-get install {package}
Error in other languages:
xenperf: bevel nie gevind nie
xenperf: comandă negăsită
xenperf: comando não encontrado
xenperf: commande introuvable
xenperf: command not found
xenperf: käsku ei ole
xenperf: không tìm thấy lệnh
xenperf: komanda nerasta
xenperf: Kommando nicht gefunden.
xenperf: kommandot finns inte
xenperf: komut yok
xenperf: nie znaleziono polecenia
xenperf: níor aimsíodh an t-ordú
xenperf: no se encontró la orden
xenperf: no s'ha trobat l'ordre
xenperf: opdracht niet gevonden
xenperf: parancs nem található
xenperf: perintah tidak ditemukan
xenperf: príkaz nenájdený
xenperf: příkaz nenalezen
xenperf: команда не найдена
xenperf: командата не е открита
xenperf: 命令找不到
xenperf: コマンドが見つかりません