Re: USB Storage speed regression since 2.6.12

[DervishD <lkml@dervishd.net>]

    Salut Brice :)

 * Brice Goglin <Brice.Goglin@ens-lyon.org> dixit:
> Le 01.09.2005 13:36, DervishD a écrit :
> >     The lack of speed seems to affect only the OHCI driver. My test
> > was done over a PCI USB 2.0 card, ALi chipset, OHCI driver (well
> > EHCI+OHCI) and using a full speed device capable of 12MBps. The
> > average measured speeds are:
> > 
> >     - 2.4.31:           about 450Kb/seg
> >     - 2.6.11-Debian:    about 800Kb/seg
> >     - 2.6.11.12:        about 820Kb/seg
> >     - 2.6.12.x:         about 200Kb/seg
> >     - 2.6.13:           about 200Kb/seg
> Are you mounting this storage with vfat and 'sync' option ?

    Yes, that may be the problem, but I think that is not the only
problem, see below.

> IIRC, sync support for vfat was added around 2.6.12, making
> write way slower since it's now really synchron.

    The fact is that if I mount the device under 2.4.31 using the
'sync' option, the speed are the ones shown above, but if I mount
them with 'async', the speed is that of the light ;) I mean, the
'sync' option is doing something even in 2.4.31. The same applies to
2.6.11, but I have to test in 2.6.12 & 13.

    Thanks for your help. If the problem is just that, the sync
option, I'll drop a note to the mailing list. Merci mille fois ;)

    Raúl Núñez de Arenas Coronado

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