[MPlayer-users] k62/500 / 256mb ram not enough for dvd-playback?

Winner of tha face compo gabucino at mplayerhq.hu
Thu Apr 3 09:16:03 CEST 2003

D Richard Felker III wrote:
> Actually, in your case, it may make it slower... Most Super7
> motherboards (used with K6) have an idiotic design flaw where they
> cannot cache memory above 128 megs, so your system would probably get
> a lot faster if you dropped down at only 128 megs of ram instead of
> 256.
You've told this so many times that today I decided to investigate this.
I have a VIA MVP3 chipset with 192Mb RAM.

A quick benchmark with different memory sizes (mem= option passed on boot)
showed that I got a whooping 18% performance increase with 128Mb RAM:

BENCHMARKs: VC:  10.920s VO:   6.664s A:   0.000s Sys:   0.494s =   18.078s
BENCHMARKs: VC:   8.620s VO:   6.221s A:   0.000s Sys:   0.476s =   15.317s

Using only 64Mb didn't make a difference (sigh).

Then I RTFMed a bit, looking for a kernel patch for this functionality.
Fortunately, the kernel already contains a driver for this in its MTD
subsystem: slram.o

With this driver it's possible to map any memory address to character and
block devices (compile mtdblock.o and/or mtdchar.o).

/dev/mtd0:      character special (90/0)
/dev/mtdblock0: block special (31/0)

Setting it up couldn't be simpler:
modprobe slram map=DRAM,134217728,+0x04000000 (adds 64Mb RAM above 128Mb)
mkswap, swapon, and ready: 128Mb physical plus 64Mb swap, and 18% faster

My other (diskless) box has only 32Mb RAM, so even MPlayer gets killed by
the kernel sometimes. But with slram.o, I could map 32Mb from the 64Mb memory
of the Geforce2 :)

01:00.0 VGA compatible controller: nVidia Corporation NV11 [GeForce2 MX] (rev b2) (prog-if 00 [VGA])
        Subsystem: Asustek Computer, Inc.: Unknown device 403d
        Flags: bus master, 66Mhz, medium devsel, latency 248, IRQ 11
        Memory at e4000000 (32-bit, non-prefetchable) [size=16M]
        Memory at d8000000 (32-bit, prefetchable) [size=128M]
        Expansion ROM at <unassigned> [disabled] [size=64K]
        Capabilities: [60] Power Management version 2
        Capabilities: [44] AGP version 2.0

modprobe slram.o map=VRAM,0xda000000,+0x02000000

root at rena:~# cat /proc/swaps 
Filename                        Type            Size    Used    Priority
/dev/mtdblock0                  partition       32760   0       -2

(however, the binary-only nvidia driver doesn't honour the VideoRAM option
of XFree86 (!), so starting for example a 3D app makes XFree86 die.)

MPlayer Core Team
 - Debian? - "This is our project and we can do whatever we want with it."
				Michael Stone <mstone#debian.org>
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