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SubjectRe: finding out the value of HZ from userspace
Micha Feigin wrote:
> On Sat, Mar 20, 2004 at 12:28:00PM +0100, Stefan Smietanowski wrote:
>
>>>>>there is one. Nothing uses it
>>>>>(sysconf() provides this info)
>>>>
>>>>Seems to me that it would be fairly trivial to modify those programs
>>>>(that should use this mechanism but don't) to use it? So why should
>>>>they be allowed to dictate kernel behaviour?
>>>
>>>
>>>quality of implementation; for example shell scripts that want to do
>>>echo 500 > /proc/sys/foo/bar/something_in_HZ
>>>...
>>>or /etc/sysctl.conf or ...
>>>
>>
>>Then write a simple program already. How hard is it to write a program
>>that does a sysconf() and returns (as ascii of course) just the
>>value of HZ? Then do some trivial calculation off of that.
>>
>>HZ=$(gethz)
>>
>>If your 500 was 5 seconds, do
>>
>>TIME=$[HZ*5]
>>echo $TIME > /proc/sys/foo/bar/something_in_HZ
>>
>
>
> Will this be USER_HZ or kernel HZ?
> Someone earlier suggested it would be USER_HZ which would make it
> pointless.

It has to be whatever enables user space to correctly interpret values
sent to user space as "ticks". That means USER_HZ and it's not useless
as it enables USER_HZ to be different and/or change without breaking
programs that use values expressed in "ticks".

>
>
>>I mean, come on.
>>
>>Then you include it in the default distro of choice so that
>>everybody can use it and there you are.
>>
>>If someone doesn't have "gethz" then they can download it.
>>
>>// Stefan
>>
>
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