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SubjectRe: kupdate & laptop's [patch for integration of mobile-update]
Zack Weinberg writes:
> Richard Gooch wrote:
> > Peter Englmaier writes:
> > > I tried to deactivate everything, but even in single user mode and
> > > no process or daemon running, I get disk I/O. Yes it stops after a
> > > while, but a simple 'ls' triggers new activity even if all is in
> > > cache already (ls finished and a second later the disk i/o happens).
> > > Perhaps this is some timestamp business, and how can I hope to patch
> > > every user land command to avoid it? With mobile-update you can
> > > edit, compile, run programs without any disk i/o.
> >
> > There must be something wrong in your setup. I don't experience these
> > problems. If a simple <ls> triggers a spin-up, then check to make sure
> > you're mounting with the "noatime" flag. By default, a simple read of
> > a file/directory will cause the inode access time to be updated, which
> > in turn requires the disc to be written to.
>
> Noatime helps but is not a panacea. Even with noatime set, an
> opendir/readdir/closedir sequence will spin up the disk every time.
> I have no idea why. I don't really mind ls spinning it up - if I'm
> actually working on the machine, it's fine for the disk to be
> running. I just want it off when the machine is idle, because it
> generates a ridiculous amount of heat when it's spinning.

Must be a configuration problem. If I do <ls -lF /bin> then my disc
does *not* spin up, once my cache is warm.

> I'd like to see atime updates be recorded in memory but not flushed
> back until the inode cache is shrunk, the fs is unmounted, or we
> need to write back the inode for some other reason. Sort of like
> the current handling of dtime in ext2. This should give the speed
> improvement without losing the information.

Except a big recursive diff can then lead to a delayed storm of
writes. Very annoying. One of the reasons I mount with noatime.

Regards,

Richard....
Old: rgooch@atnf.csiro.au
Current: rgooch@ras.ucalgary.ca

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