Re: Unneeded Code Found??

[Randy Appleton]

Nick Piggin wrote:

> Randy Appleton wrote:
>
> > Nick Piggin wrote: 
>
>
>
> > > Yes it gets used.
> > >
> > > I think its a lot more common with direct io and when you have lots of
> > > processes.
> >
> >
> >
> > I'm not arguing, but how do you know this?  I'm trying to convince 
> > myself that the code is used, and at least on my system
> > a few days of general use, followed by heavy parallel compiles, 
> > doesn't use the code even once.
> >
> > I have not tested direct I/O.  Otherwise it looks unused.
>
> Because I have seen it - I have instrumented it.
>
> Your usage patterns are pretty tame actually. I remember having 100 
> processes
> randomly reading from the same part of the disk was one of my test cases.
> You need direct IO otherwise everything ends up in pagecache.
>
> I haven't seen workloads where it gets used a lot, but that doesn't 
> mean they
> don't exist, and I've never seen the code cause any problems, so there 
> is no
> need to make any trade offs by removing it.
O.K.  That's convincing.  Thanks for the time.

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