Hello Chris,
On 05/23/2013 10:33 PM, Chris Mason wrote:
But I was using 8 drives. I'll try with 12.
My benchmarks were on flash, so the rmw I was seeing may not have had as
big an impact.
I just further played with it and simply introduced a requeue in
raid56_rmw_stripe() if the rbio is 'younger' than 50 jiffies. I can
still see reads, but by a factor 10 lower than before. And this is
sufficient to bring performance almost to that of direc-io.
This is certainly no upstream code, I hope I find some time over the
weekend to come up with something better.
Btw, I also noticed the cache logic copies pages from those rmw-threads.
Well, this a numa system and memory bandwith is terribly bad from the
remote cpu. These worker threads probably should numa aware and only
handle rbios from their own cpu.
Cheers,
Bernd
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