Bug 503076

Summary: Error in tuning guide
Product: Red Hat Enterprise MRG Reporter: Bryan Che <bche>
Component: Realtime_Tuning_GuideAssignee: Lana Brindley <lbrindle>
Status: CLOSED CURRENTRELEASE QA Contact: David Sommerseth <davids>
Severity: medium Docs Contact:
Priority: low    
Version: 1.1.1CC: bhu, lgoncalv, mhideo, ovasik, williams
Target Milestone: ---Keywords: Documentation
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2009-08-18 04:12:23 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description Bryan Che 2009-05-28 18:08:57 UTC 
There's a mistake on this page:
http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_MRG/1.1/html/Realtim
e_Tuning_Guide/sect-Realtime_Tuning_Guide-General_System_Tuning-gettimeo
fday_speedup.html

It talks about echo'ing values into /proc/sys/kernel/syscall64, whereas
actually the file is /proc/sys/kernel/vsyscall64. The page should
probably also document that echoing a value into this file results in an
error, although it appears to have the desired effect.
Comment 1 Luis Claudio R. Goncalves 2009-07-15 17:59:42 UTC 
Good catch, the path is wrong. On the other hand, echo'ing values is a valid operation:

[root@void ~]# cat  /proc/sys/kernel/vsyscall64 
1
[root@void ~]# echo 0 >  /proc/sys/kernel/vsyscall64 
[root@void ~]# cat  /proc/sys/kernel/vsyscall64 
0
[root@void ~]# echo 1 >  /proc/sys/kernel/vsyscall64 
[root@void ~]# echo 0 >  /proc/sys/kernel/vsyscall64 
[root@void ~]# cat  /proc/sys/kernel/vsyscall64 
0

But we should add a not, such as the one we have on the ftrace section, remeinding the reader that "1 >" and "1>" have different meanings on the shell. So, yes, "echo 1>  /proc/sys/kernel/vsyscall64" will fail.