Messages in this thread | | | Date | Tue, 30 Aug 2005 19:08:55 +0000 (GMT) | From | Holger Kiehl <> | Subject | Re: Where is the performance bottleneck? |
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On Mon, 29 Aug 2005, Mark Hahn wrote:
>> The U320 SCSI controller has a 64 bit PCI-X bus for itself, there is no other >> device on that bus. Unfortunatly I was unable to determine at what speed >> it is running, here the output from lspci -vv: > ... >> Status: Bus=2 Dev=4 Func=0 64bit+ 133MHz+ SCD- USC-, DC=simple, > > the "133MHz+" is a good sign. OTOH the latency (72) seems rather low - my > understanding is that that would noticably limit the size of burst transfers. > I have tried with 128 and 144, but the transfer rate is only a little bit higher barely measurable. Or what values should I try?
> >> Version 1.03 ------Sequential Output------ --Sequential Input- --Random- >> -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- >> Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP >> Raid0 (8 disk)15744M 54406 96 247419 90 100752 25 60266 98 226651 29 830.2 1 >> Raid0s(4 disk)15744M 54915 97 253642 89 73976 18 59445 97 198372 24 659.8 1 >> Raid0s(4 disk)15744M 54866 97 268361 95 72852 17 59165 97 187183 22 666.3 1 > > you're obviously saturating something already with 2 disks. did you play > with "blockdev --setra" setings? > Yes, I did play a little bit with it but this only changed read performance, it made no measurable difference when writting.
Thanks, Holger
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