minor optimization provides large performance gain

Paul Theodoropoulos paul at atgi.net
Thu Feb 17 17:52:48 UTC 2000


If you have a small number of disks on a feed-exchanger, I'd recommend 
trying out the 'SEQUENTIAL' mode modifier in cycbuff.conf. the 'waiting on 
I/O' statistic on my server dropped from an average of 16% down to 8% by 
making that change. I believe it's because the disk no longer has to seek 
constantly across the platters to write articles as it would in the default 
round-robin mode. here's my cycbuff.conf for reference:

cycbuff:FOU:/cycbuff/c2t3d0s4:2080000
cycbuff:FIV:/cycbuff/c2t3d0s5:2080000
cycbuff:SIX:/cycbuff/c2t3d0s6:2080000
cycbuff:SEV:/cycbuff/c2t3d0s7:430000

cycbuff:EIG:/cycbuff/c2t4d0s3:2080000
cycbuff:NIN:/cycbuff/c2t4d0s4:2080000
cycbuff:TEN:/cycbuff/c2t4d0s5:2080000
cycbuff:ELE:/cycbuff/c2t4d0s6:2080000
cycbuff:TWE:/cycbuff/c2t4d0s7:430000

metacycbuff:ALLELSE:FIV,SIX,SEV,TWE:SEQUENTIAL
metacycbuff:BINARIES:FOU,EIG,NIN,TEN,ELE:SEQUENTIAL

this might be something to note in the INSTALL docs. my system is solaris 
7, snapshot inn-2000-02-05_03-01. Of course, if you have lots of spindles, 
then having buffers staggered over those spindles writing in round-robin 
that would surely be the faster design.


---------------------------------------------------------------------
Paul Theodoropoulos                        Advanced TelCom Group Inc.
Senior Unix Systems Administrator          Internet Services Division
paul at atgi.net                              Santa Rosa, California, US
Work: http://www.atgi.net             Play: http://www.anastrophe.com
"Reliability means never having to say you're sorry." -D.J. Bernstein




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