Multi-core join performance
Hi, I am joining two tables, each with 32K tuples. The query runs for ~23-24 seconds on my (multi-core) machine. During execution, however, only 1 core is utilised, while the rest of the CPU cores are idle. The cores are under-utilised although I have configured the MonetDB server to use all the physical cores of my machine (either by setting 'nthreads' or, in the case of mserver5, 'gdk_nr_threads'). I am running MonetDB server v11.21.13 "Jul2015-SP2", compiled from source. Is this due to some configuration setting I missed? Or, due to the fact that I am running a single-operator query? Alternatively, I was thinking of creating merge tables, thus partitioning my tables manually, hoping that this will allow for intra-operator parallelism. Thanks, Alexandros
Hi This is insufficient information to shed light on it. Crucial information is system characteristics. And also a TRACE of your query can shed light on the issue. Furthermore, is it a cold or hot execution of the query? regards, Martin On 20/01/16 13:24, Alexandros Koliousis wrote:
Hi,
I am joining two tables, each with 32K tuples. The query runs for ~23-24 seconds on my (multi-core) machine.
During execution, however, only 1 core is utilised, while the rest of the CPU cores are idle. The cores are under-utilised although I have configured the MonetDB server to use all the physical cores of my machine (either by setting 'nthreads' or, in the case of mserver5, 'gdk_nr_threads').
I am running MonetDB server v11.21.13 "Jul2015-SP2", compiled from source.
Is this due to some configuration setting I missed? Or, due to the fact that I am running a single-operator query?
Alternatively, I was thinking of creating merge tables, thus partitioning my tables manually, hoping that this will allow for intra-operator parallelism.
Thanks,
Alexandros
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participants (2)
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Alexandros Koliousis
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Martin Kersten