On 23 Oct 2012, at 19:45, Elvis Dowson wrote: > Hi, > I noticed that between commits > > http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=0260bb5c6978839c068007fcff2f704937805faf > > and > > http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=a3d5e9e6b7729319c518dcaf25bbe0643bfb25db > > the build time has improved by around 7 minutes for my machine configuration, > for building a core-image-minimal rootfs for the Xilinx ZC-702 FPGA with dual > ARM Cortex A-9 CPUs. > > commit id 0260bb5c6978839c068007fcff2f704937805faf took 29 minutes > commit id a3d5e9e6b7729319c518dcaf25bbe0643bfb25db took 22 minutes > > The machine configuration is an Intel i7 3770K over-clocked to 4.2GHz, with > 16GB RAM at 1600Mhz, two 120GB SSDs configured into a striped disk array > (Intel 330 series SSDs) with a write performance of 838MB/s and read > performance of around 600MB/s, in RAID0 configuration, with a Corsair HT100 > liquid CPU cooler keeping the CPU cool at around 52 degree centigrade during > the build process. The motherboard is a gigabyte GA-Z77X-UP5TH > > http://www.gigabyte.com/products/product-page.aspx?pid=4279#ov > > This motherboard has a thunderbolt display port, so I can re-use my existing > Apple Thunderbolt display. I've run Ubuntu 12.04.1 LTS and Ubuntu 12.10, and > it appears to work after a few tweaks. > > The only curious thing that I've noticed is that I don't see a large > performance improvement using a standard 3TB Seagate Barracuda 7200 RPM HDD, > and the two Intel Series 330 SSDs in a striped RAID0 configuration. The read > (600MB/s) / write (838MB/s) figures are impressive, although I expected the > read performance to be higher than write performance, as is normally with a > single SSD. I'm using the motherboard's hardware RAID support on a 6GB/s SATA > 3 port. > > The 3TB HDD took the approximately 2 or 3 minutes longer than the 120GB x 2 > RAID0 SSD configuration for commit id > 0260bb5c6978839c068007fcff2f704937805faf (31 minutes vs. 29 minutes). > > My local.conf parallelism settings were set to 6 threads for bitbake and > make, for the quad-core (virtual 8 cpu cores)system. > > Has anyone tried yocto builds with a 6-core, 8-core or 10-core Xeon processor > system? How do those figures fare? I'm thinking my current bottleneck might > be the CPU and not the HDD (?!), for the yocto build workloads, which I find > curious and would like to confirm.
I did quite a bit of experimenting with this a while back (similar spec, but with nearly 1000MB/s read/write SDD array). CPU was quad core with hyper-threading, so 8 virtual cores. I generally run with 16 threads, 16 parallel make as I find that the main performance hit is running out of stuff to keep all the cores busy. Most of the time all 8 cores are maxed out, but around when the kernel gets built (and cross tools needed for it) I see the total CPU use drop to about 25%. This isn't because the system is I/O bound; it simply doesn't have enough tasks ready to run at that point in time. I estimate that my 55 min build times would come down by 10 to 15 minutes if I could keep the CPUs busy (still, much better than the 10 hour build times on my previous system!). I tried 'tinkering' with the run queue priority order, but all I proved was that inverting it (i.e. make the things that were previous given high-priority have low-priority) made no measurable difference to my build times! I'm trying not to think too much about that one ;-) Chris Tapp opensou...@keylevel.com www.keylevel.com _______________________________________________ yocto mailing list yocto@yoctoproject.org https://lists.yoctoproject.org/listinfo/yocto
