Re: ext3 IO latency measurements

Giacomo A. Catenazzi
2009-03-27T12:06:44Z

Alan Cox wrote:
>> And what's the argument for not doing it in the kernel?
>>
>> The fact is, "atime" by default is just wrong.
>
> It probably was a wrong default - twenty years ago. Actually it may well
> have been a wrong default in Unix v6 8)
>
> However
> - atime behaviour is SuS required

so I propose an other mount option along to strictatime:
nowatime: it give the actual time as atime:
it is totally useless, but fast *and* POSIX compatible:
- no disk writes on accesses
- POSIX doesn't mandate the behaviour of other processes, so
we simulate that fs are scanned at every fs-tick.
- IMHO more programs break, but in this case only
the POSIX incompatible programs.

> - there are users with systems out there using atime and dependant on
> proper atime

This is the real problem.

ciao
cate