Re: HIGHMEM=4G slows down ps2pdf with 2.4.28

[Marcelo Tosatti <marcelo.tosatti@cyclades.com>]

On Mon, Dec 06, 2004 at 04:41:18PM -0200, Marcelo Tosatti wrote:
> On Fri, Dec 03, 2004 at 09:58:19PM +0100, Alain Tesio wrote:
> > On Thu, 2 Dec 2004 17:08:15 -0200
> > Marcelo Tosatti <marcelo.tosatti@cyclades.com> wrote:
> > 
> > > On Wed, Dec 01, 2004 at 11:25:22PM +0100, Alain Tesio wrote:
> > > > Hi,
> > > > 
> > > > With a 2.4.28 kernel, 1.5 Go RAM and nothing exotic, everything works fine
> > > > with CONFIG_HIGHMEM4G and CONFIG_HIGHMEM=y except that
> > > > ps2pdf is about 30 times slower 
> > 
> > > How does /proc/mtrr look like? 
> > > 
> > > Maybe some of your memory is configured as uncacheable.
> > 
> > reg00: base=0x00000000 (   0MB), size=1024MB: write-back, count=1
> > reg01: base=0x40000000 (1024MB), size= 256MB: write-back, count=1
> > reg02: base=0x50000000 (1280MB), size= 128MB: write-back, count=1
> > reg03: base=0x58000000 (1408MB), size=  64MB: write-back, count=1
> > reg04: base=0x5c000000 (1472MB), size=  32MB: write-back, count=1
> > reg05: base=0x5e000000 (1504MB), size=  16MB: write-back, count=1
> > 
> > I don't think that the hosting company played with the bios settings,
> > and I don't do anything special with memory.
> 
> Alain,
> 
> All memory is correctly configured in MTRR it seems (all of it is write-back cacheable).
> 
> Do you have CONFIG_HIGHIO=y ? That might help a lot. The kernel has to use 
> bounce buffers for IO otherwise.

However you report 30x slower without HIGHMEM - thats a bit too much for 
the added overhead of bounce buffers. Anyway, try CONFIG_HIGHIO=y if you 
dont have it configured this way.