Would be useful if you could get flamegraphs when you run into this. See
https://github.com/brendangregg/FlameGraph
Once we have that, the we can have a better understanding of what's
going on and we can dtrace it further to figure it out.
-Sanjay
On 8/23/18 5:47 AM, w.kruzel via openzfs-developer wrote:
It's interesting what you said, as I have two examples (both with
different Intel nvme disks) that show otherwise.
Being nvme, I was expecting read performance from L2ARC at 2GB/s+
levels, yet I only get ~200MB/s read speeds when I certainly know it
is being read from L2ARC.
When tested (details in my earlier post), I can get the same speed
with nvmecontrol perftest that is single threaded.
Multi threaded perftest gives 2GB/s + output.
I also have this raised with FreeNAS where one of their devs tested it
on other make L2ARC he had installed and confirmed that it looks like
single threaded process.
Can someone look into this please?
It is a major performance hit for L2ARC, making it not really fit for
purpose :(
Kind regards,
Wojciech Kruzel
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