Scrypt LTC/NVC mining issue - Linux guru's required

[Clearfly]

Having an issue getting --thread-concurrency up to what it should be capable of.

System Setup:
XFX 5870 1GB
4GB onboard ram
Running Ubuntu 12.04 off USB 8GB pendrive
Running CGminer 2.11.4
ATI drivers 13.1 and SDK 2.8 (all 32bit)

Only achieving about 150Mh/s and can't get above --lookup-gap 2 --thread-concurrency 2048 as it complains the memory buffer exceeds 1GB.
It's as if it's only making use of 1GB of dram on the card and not using the available system RAM.
System monitor in Ubuntu reports 3GB system Ram is free.

Note similar setup on my Windows Vista machine running a 5850 1GB can reach 340Mh/s+ with --lookup-gap 2 --thread-concurrency 8192 and that only has 2GB system ram.

So any linux guru's out there no why my Ubuntu setup is not making use of the system ram of scrypt mining?
Is it because i'm running off USB so it's reserving Ram for swap/ramdrive? If so how do i free some of it up?

Edit:
BTW it all runs full wack no issues with SHA256 coins BTC/PPC/TRC.

Cheers

[-ck]

I don't suppose you've read the SCRYPT-README that I spent ages documenting.

[Clearfly]

Ye CK been through the SCRYPT-README

It's just not making use of the available system ram or running a headless Ubuntu setup off USB is meaning Ubuntu is reserving all the ram for itself (even though it says 3GB is free)

[dorei]

try

Code:

export GPU_MAX_ALLOC_PERCENT=100
export GPU_USE_SYNC_OBJECTS=1

before starting cgminer

[Clearfly]

try

Code:

export GPU_MAX_ALLOC_PERCENT=100
export GPU_USE_SYNC_OBJECTS=1

before starting cgminer

Ye already got all that in and 'export DISPLAY=:0'

[Clearfly]

bump 

[CoinHoarder]

--lookup-gap 2 has always crashed cgminer for me using any 5xxx card whether it be *nix or d0ze.

However, -g 1 (--lookup-gap's alternate syntax) has worked on every rig I've ever tried it on, so this might be the issue.

I usually use something along the lines of:

export DISPLAY=:0
export GPU_USE_SYNC_OBJECTS=1
export GPU_MAX_ALLOC_PERCENT=100

screen ./cgminer --scrypt -o give-me-ltc.com:8080 -u user -p password --thread-concurrency 8000 -I 18 -g 1 -w 256 --auto-fan --auto-gpu

[Clearfly]

Ye i always run --g 1 (gpu threads 1).

Might have to slip in one setup with an SSD hard drive with Ubuntu on it instead of using a USB pendrive, and see if that makes a difference.
I'm convinced Ubuntu is grabbing all the ram for itself somehow because it's running off USB, but i'm not that familiar with Linux so i don't know where to control/reduce what it decides it will reserve for itself.

[CoinHoarder]

Ye i always run --g 1 (gpu threads 1).

Might have to slip in one setup with an SSD hard drive with Ubuntu on it instead of using a USB pendrive, and see if that makes a difference.
I'm convinced Ubuntu is grabbing all the ram for itself somehow because it's running off USB, but i'm not that familiar with Linux so i don't know where to control/reduce what it decides it will reserve for itself.

Certainly sounds like software/settings issue.

Try using BAMT on that USB stick.

MapleSyrupGhost's guide: http://www.bitcointrading.com/forum/linux-distros/bamt-version-0-5-easy-usb-based-mining-linux-with-farm-wide-management-tools/msg1835/#post_lazylitecoin

I've had no issues using this and usually can have a rig setup and installed in about 15 minutes.

I like to use xrdp to remote in from windows, install it like:
apt-get install xrdp

Remember to change the default password in bamt, otherwise you wont be able to remote in.

Good luck!

[Remember remember the 5th of November]

I don't suppose you've read the SCRYPT-README that I spent ages documenting.

Well I'll be damned, you actually came into this section?