Hi Derick,

Thu, 12 Sep 2013 11:18:35 +0200
Derick Swanepoel <dswanep...@gmail.com> ==> Lars Täuber <taeu...@bbaw.de> :
> Hi Lars,
> 
> Sorry, I neglected to mention my ggaoed config. I used direct IO for all 
> tests (except the ramdisk which can't be opened with O_DIRECT). queue-length 
> was 128, ring-buffer-size was 4096.
> 
> Increasing queue-length from 16 through to 128 increased performance to the 
> speeds I reported previously (it was about 200 MB/s at the default 
> queue-length of 16). Anything bigger than 128 had no effect.
> 
> Increasing the ring buffer size beyond the default 4096 kB had no discernible 
> effect.
> 
> Disabling direct IO or enabling merge-delay decreased performance for all 
> tests.

thanks for this info.
I wonder what the machine is doing when the ggaoed doesn't use any cpu cycle. I 
suspect that there must be something forcing waits.

[...]
> >> 
> >> Test            MB/s      CPU       AvgPktSz  Direct MB/s   CPU     
> >> AvgPktSz
> >> Disk Read  538       95%    2083         623        67%     4333
> >> Disk Write 443       97%    2095         582        75%     4345
> >> Ramdisk Read       655       97%    2083         778        69%     4333
> >> Ramdisk Write      424      100%    2095         624        81%     4345
> >> 
[...]
> >> I also tried other Linux targets:
> >> 
> >> ggaoed: About 25% slower than vblade:
> >> 
> >> Test               MB/s     CPU  Direct MB/s  CPU
> >> Disk Read   446     71%     446       51%
> >> Disk Write  355     63%     557       56%
> >> Ramdisk Read        531     91%     627       67%
> >> Ramdisk Write       399     85%     602       73%

ggaoed uses the fewest cpu cycles from all targets. It seems to use about 25% 
less cycles to be 25% slower.

It's a pity that Gábor gave up further developement on ggaoed. 

Regards
Lars

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