In the following kernel commit, support for the timerfd() syscall was added (in kernel 2.6.22):

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commit b215e283992899650c4271e7385c79e26fb9a88e                                 
Author: Davide Libenzi <davidel@xmailserver.org>                                
Date:   Thu May 10 22:23:16 2007 -0700                                          
                                                                                
    signal/timer/event: timerfd core                                            
====

Then in the following kernel commit, support for timerfd() was removed and instead the timerfd_create(), timerfd_gettime(), timerfd_settime() syscalls were added (in kernel 2.6.25):

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commit 4d672e7ac79b5ec5cdc90e450823441e20464691                                 
Author: Davide Libenzi <davidel@xmailserver.org>                                
Date:   Mon Feb 4 22:27:26 2008 -0800                                           
                                                                                
    timerfd: new timerfd API                                                    
====

systemtap has syscall/nd_syscall support for timerfd(), but not for timerfd_create(), timerfd_gettime(), or timerfd_settime()