Re: AW: Slow I/O on USB media after commit f664a3cc17b7d0a2bc3b3ab96181e1029b0ec0e6

Andrea Vai
2019-11-28T07:47:04Z

Il giorno mer, 27/11/2019 alle 08.14 +0000, Schmid, Carsten ha
scritto:
> >
> > > Then I started another set of 100 trials and let them run
> tonight, and
> > > the first 10 trials were around 1000s, then gradually decreased
> to
> > > ~300s, and finally settled around 200s with some trials below
> 70-80s.
> > > This to say, times are extremely variable and for the first time
> I
> > > noticed a sort of "performance increase" with time.
> > >
> >
> > The sheer volume of testing (probably some terabytes by now) would
> > exercise the wear leveling algorithm in the FTL.
> >
> But with "old kernel" the copy operation still is "fast", as far as
> i understood.
> If FTL (e.g. wear leveling) would slow down, we would see that also
> in
> the old kernel, right?
>
> Andrea, can you confirm that the same device used with the old fast
> kernel is still fast today?

Yes, it is still fast. Just ran a 100 trials test and got an average
of 70 seconds with standard deviation = 6 seconds, aligned with the
past values of the same kernel.

Thanks,
Andrea