Thanks. I am thinking of buying a new 4 core laptop later this year so was curious to know if the 8 thread hyperthreading would help that much over the 4 cores without hyperthreading. Actually I don't think there will be a non-hyperthreading option. I put in an SSD last week and now I'm compute bound on my 2 core, 2 thread Lenovo T500. My IO speed would also increase due to a doubling of my SATA bandwidth.
On 9/18/13 11:03 PM, David Holmes wrote: > On 19/09/2013 7:43 AM, Pete Brunet wrote: >> If a machine has 4 cores and 8 threads will the jdk8 build run faster >> than one with 4 cores and 4 threads? > > All depends on where the bottlenecks are. Given a build is pretty much > I/O bound I wouldn't expect much difference. > >> If so would it be a 2x decrease in build time? > > No. The CPU component of the build will be a fraction of the I/O > component. > > Even a compute bound task won't see a 2x difference when run on twice > the number of hardware threads as they share physical resources in the > core so can't completely run in parallel. > > > Would the build explicitly take advantage of the >> hyper-threading or would any increase in performance be a side effect? > > The build like most other software on the system knows nothing about > processors, cores and (hyper)-threads. The OS presents a model where > all of those things represent logical processors and it runs native > threads on each logical. > > Trying to do too much in parallel can easily degrade performance - you > need to understand how Amdahls Law applies to the computation you are > doing. > > David > > >