Re: Badblocks and no free pages...

Rogier Wolff (
Sun, 4 May 1997 18:15:30 +0200 (MET DST)

Doug Ledford wrote:
> > Can I report the following as bugs:
> > - The fact that badblocks doesn't help prevent accidents is a bit unfortunate.
> > - The fact that it generates "Couldn't get a free page" seems bad.
> > In particular, why should this happen during writing? What needs to
> > do an atomic page allocation?
> It's all because we are filling up all available RAM with write behind
> buffers. Whenever it can't get a free page, it simply waits for some to
> become available. Not a bug really, just shows us that the program is
> writing as fast as it can.

Ho! stop. The "couldn't get a free page" is when kmalloc gets a request
that it has to pass on, and that this request couldn't get honoured. It
was requested at a level that didn't allow sleeping or even the sleeping

> > - The unusable sluggishness of the machine is a bug.
> It was never intended to be something that you would run during normal
> usage, it's a shake down, tear the drives and controllers apart type test
> that should be run when you are aware of what these types of tests do to
> machine performance and are prepared to wait for it to finish before
> actually trying to do anything :)

Actually having several programs write like hell filling all available
memory with write-behind buffers is not that unlikely. The kernel
should somehow try to make this situation feel less sluggish.