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Alex Granovsky
gran@classic.chem.msu.su

you can try to add:

 $intgrl packao=.f. $end 

to your input to disable 2-e AO integrals packing and
to increase I/O overhead; and compare again. It is also
interesting to check how the async I/O turned on will
affect performance:

 $system async=1 $end 

(the Linux-specific default is zero i.e no async I/O in most cases).

Finally, you can check how various I/O tuning options affects performance, e.g., I/O buffer sizes (see e.g. http://classic.chem.msu.su/cgi-bin/ceilidh.exe/gran/gamess/forum/?C34df668afbHW-7264-1168+00.htm)

For example,

 $system
   freshf=.t.
   ioflgs(8)=0xC020 
   aiobuf=8192 
   mxiob(1)=256,128
 $end

will permanently (freshf=.t.) set unit 8 (ioflgs(8)) that is
normally connected to AOINTS file to direct unbuffered constant
block size read mode (0x4000) with deferred (0x8000) async I/O (0x20)
(as 0xC020 = 0x8000 + 0x4000 + 0x20). The intermediate per unit
buffer for async I/O will be set to 8 MBytes (aiobuf=8192),
while the system wide I/O chunk size will be 256 KBytes for disk
reads and 128 KBytes (or smaller) for writes (mxiob(1)=256,128).

Regards,
Alex






On Thu Feb 25 '10 3:55pm, Denis Zavelev wrote
---------------------------------------------
>Hello, Alex!

>Thanks for the reply.
>Yes, it seems that for my case SSDs will be enough (retailer promised me 3-year warranty). I started 2 similar tasks (DFT computation of Ti-Cu oxide system) on 2 workstations:
>1. Core2Quad Q6600 @ 2.40GHz / 4Gb DDR2-6400 / 4x320Gb SATA HDD / reiserfs / Ubuntu 8.10 amd64
>2. Phenom II X4 965 BE @ 3.40GHz / 8 GB DDR3-12800 / SATA II HDD (system) + 2x128Gb SATA II SSD / ext4 (without journaling) / Ubuntu 9.10 amd64
>and compared cpu utilization. In first case it's about 70%, in 2nd case it's about 99.5%.
>Thus for my typical tasks 1 SATA II SSD per 2 cores (physical or logical if I get Core i7 someday) is enough. So we need just to test how long will these SSDs work.

[ This message was edited on Sat Feb 27 '10 at 9:26pm by the author ]