using mfs of size > 64Mb and system stability

[Kris Kennaway]

On Mon, Jan 10, 2005 at 11:11:44AM +0100, Poul-Henning Kamp wrote:
> In message <20050110100840.29845.qmail at web30301.mail.mud.yahoo.com>, Barath S w
> rites:
> >Initially, I didn't go for swap based fs as I felt
> >that  the memory occupied will be from the swap area.
> >As you are saying that the allocation will be from
> >buffer/cache, I will test swap-mfs.
> 
> malloc backing should not be used for large disks.
> 
> If you _truly_ want to have a large disk which is memory backed,
> you should consider using the "preload" backing as this will withdraw
> the memory entirely from the kernels use.
> 
> In general, the benefit from using RAM disks is much smaller than
> most people realize.

I've found that using a swap-backed disk substantially cuts back on
disk accesses for my purposes (package building, where everything that
hits disk will be deleted again in a few minutes).  It appears to give
a reasonable performance boost, which I'm still trying to measure.
Unfortunately, swap-backed md under 6.x deadlocks under some
conditions which are being investigated.

Kris
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