Hi Aidan, > > T420 > work_mem = 512MB > > MacMini > work_mem = 32MB > > So that is why the T420 does memory sorts and the mini does disk sorts. > > I'd start looking at why memory sorts on the T420 is so slow. Check your > numa settings, etc (as already mentioned). > > For a drastic test, disable the 2nd socket on the dell, and just use one > (eliminate any numa/QPI costs) and see how it compares to the no-numa MacMini. >
the command dmesg | grep -i numa doesn’t display me anything. I think T420 hasn’t NUMA on it. Is there a way to enable it from Ubuntu? I don’t have immediate access to BIOS (server is in another location). For QPI I don’t know what to do. Please, can you give me more details? > If you want to see how bad the NUMA/QPI is, play with stream to benchmark > memory performance. With stream you refer to this: https://sites.utexas.edu/jdm4372/tag/stream-benchmark/ ? Do you suggest me some way to do this kind of tests? Thank you very much Pietro