Recently I’ve had a few folks ask me how to fix missing Perfmon counters for SharePoint 2010. For various reasons, you might be missing some or all of your SharePoint related counters. The process is pretty easy. You need to use RegSvr32.exe to register the DLLs that contain the counters. The KB below explains the RegSvr32 command. The DLLs you’ll need to register are listed below.
http://support.microsoft.com/kb/249873

C:\Program Files\Microsoft Office Servers\14.0\Bin\Microsoft.Office.Server.PerfmonMsg.dll
C:\Program Files\Microsoft Office Servers\14.0\Bin\Microsoft.Office.Web.Environment.Sharepoint.ULS.Perfmonmsg.dll
C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\BIN\1033\Microsoft.SharePoint.PerfmonMsg.dll