Re: vfs: Add MS_FLUSHONFSYNC mount flag

From: Fernando Luis Vázquez Cao
Date: Mon Feb 16 2009 - 02:47:38 EST


On Sun, 2009-02-15 at 17:54 -0500, Theodore Tso wrote:
> On Sun, Feb 15, 2009 at 04:23:26PM +0900, Fernando Luis VÃzquez Cao wrote:
> > You mentioned "we should integrate this with the barrier settings". Do
> > you imply we should make it a per-device tunable too? Should we keep the
> > barrier-related mount options some filesystems provide?
> >
>
> Making barriers to be a per-device tunable makes sense. The only
> reason why we kept it as a mount option in ext4 is for benchmarking
> purposes, and in ext3, because the filesystem predated the barrier
> code, and there was a desire to be able to benchmark with and without
> the old behavior --- and because akpm is still worried about the
> performance hit of the barrier code, so he's been resistant about
> change the default for ext3.

Ok, I'll turn both barriers and flushonfsync into a sysfs-exported
per-device knob and see how it turns out.

By the way, should we also add/keep a mount option for "benchmarking
purposes"?. I guess that once we get the per-device tunable we probable
do not need it anymore.

Regards,

Fernando

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