Re: Desktop Kernel Stuff

[Alan Cox <alan redhat com>]

> 	There are several potential solutions; probably the best is the kernel
> tracking / recording per-process disk access patterns, and doing more
> intelligent, speculative, batch elevated read-ahead - if that makes any
> sense.

Some work is being done there - its actually not very easy. Preloading
binaries on big machines is one approach

> 	Also - on the swap side; better paging - not knowing how the algorithm
> works (and being none the wiser for having read the docs) - I'll waffle:
> It seems that a more chunky approach for page recovery geared with

Chunkiness is configurable actually.

	echo "value" >/proc/sys/vm/page_cluster

Where we cluster 1<<value pages per swap read/write

> 	Simply recognising and optimising for the use-case of a series of
> single process being run for several minutes before switching to another
> single process, rather than myriad interleaved concurrent transactions
> all of which have to be fairly balanced would be most useful.

The interesting thing is that isnt what you actually see. The system does
tend to optimise for that anyway, its trying to keep data around that you
are using, which means it will tend to keep the pieces being used of the
app you are using mainly.

Some of the results on low memory boxes go back to the X server behaviour
and whether you should always keep display buffers (moving a window tends
to bring each app into RAM to scribble rectangles). Another is the amount
of stuff Gnome seems to be doing during startup which does want measuring.
On my boxes I'm seeing cpu idle, disk idle and completely idle patches.

XFce + rox starts in about 3 seconds (from X cursor appearing to ready).

Alan