On 20/02/13 06:51, Josh Berkus wrote:
On 02/18/2013 08:28 PM, Mark Kirkwood wrote:
Might be worth looking at your vm.dirty_ratio, vm.dirty_background_ratio
and friends settings. We managed to choke up a system with 16x SSD by
leaving them at their defaults...
Yeah? Any settings you'd recommend specifically? What did you use on
the SSD system?
We set:
vm.dirty_background_ratio = 0
vm.dirty_background_bytes = 1073741824
vm.dirty_ratio = 0
vm.dirty_bytes = 2147483648
i.e 1G for dirty_background and 2G for dirty. We didn't spend much time
afterwards fiddling with the size much. I'm guessing the we could have
made it bigger - however the SSD were happier to be constantly writing a
few G than being handed (say) 50G of buffers to write at once . The
system has 512G of ram and 32 cores (no hyperthreading).
regards
Mark
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