On 23-Oct-2017 Filippo Mantovani held a talk in Darmstadt on “Mobile technology for production-ready high-performance computing systems: The path of the Mont-Blanc project”. Unfortunately I was unable to attend, but Mr. Mantovani sent me his Darmstadt Seminar slides. As his slides and documents are very interesting to people using or intending to use ARM in HPC, I copy these documents here, so they are easily available. I also copied a report on “MB3_D6.4 Report on application tuning and optimization on ARM platform“.
HP (Hewlett Packard) manufacturer of printers of various sorts (laser, ink) unfortunately again decided to annoy its loyal customers. Repeatedly HP updated firmware in printers so that do not work with alternate ink, see for example Disabling 3rd-party ink ensures “best printing experience”. Now for the last years they disabled the so called apps (ePrint functionality): after a few years the printer can no longer connect to the web-services of HP. See, for example, HP Apps Service Retired on several printers.
In my case, I bought a CM1415 in November 2011. It can no longer connect to HP web-services. Therefore I can no longer send e-mails to the printers which then get printed. In November 2014 I bought an M276nw, a similar printer as the CM1415. This model can still connect to HP web-services. So it looks like after six years HP silently disables functionality. These web-services also offer other services, like weather forecasts, news, sudokus, etc.
These chicanery make it clear that customers should not trust cloud-services, or at least have a contingency plan if these services do not work, or have prices which are ridiculous. Recently the price increase by Firebase made headlines, see Firebase Costs Increased by 7,000%!
There is a big difference between noise-cancelling headphones, and classical headphones without noise-cancelling ability! Especially when you use them in a noisy environment, like a plane or a large office bureau. Inspired by a positive review of the Bose headphones by Marques Brownlee, I bought them.
Here is the review:
Pairing with my OnePlus One smartphone was completely automatic and works like a charm. No further explanation is required.
Paring with a PC/laptop running Arch Linux needed a little more effort. Some advice in Bluetooth headset helped me alot.
systemctl start bluetooth.service hciconfig hci0 up piscan pacmd list-sinks | grep index: bluetoothctl
help show devices pair xx:yy:... trust xx:yy:... connect xx:yy:... paired-devices
I had to delete the directory below
/var/lib/bluetooth. Apparently something was stored there which shouldn’t have been there.
Once the pairing works, as described above, I just use:
systemctl start bluetooth.service hciconfig hci0 up piscan
for starting bluetooth and making my PC with bluetooth visible. I switch on the headphone, which normally finds the PC in less than a second. Then I have to set the right sink via
pacmd set-default-sink `pacmd list-sinks | grep index: | tail -1 | cut -d " " -f6`
Checking that all is well is:
pacmd list-sinks | grep index:
Once paired with your Linux machine, yo have to repeat
set-default-sink if you lose the connection to your Linux machine, for example by walking too far away. If you lose Bluetooth connection apparently sound output will go to the regular speakers of your Linux machine. In case you are working in a large office other people will hear your music. Of course, you can mute the regular loudspeakers of your Linux machine using
pacmd set-sink-volume 0 0
assuming sink #0 is regular loudspeaker.
Added 13-Oct-2017: Arch Linux dropped
hcictool from package bluez-utils since version 5.44. My latest good package still containing these commands is 5.43-2, for easy reference located here bluez-utils-5.43-2-x86_64.pkg.tar.xz. Download it and use ascii2hex.c to convert from hex to ascii/binary because WordPress.com does not allow XZ-files.
In Hard-Disk and SSD Speed Comparisons I compared a Mushkin SSD with 60 GB against a ADATA with 128 GB against a Seagate 1 TB hard disk drive. The SSD’s had roughly three times the speed of the hard disk drive. I.e., 380 MB/s vs. 134 MB/s for reading Mushkin vs. Seagate, and 297 MB/s vs. 131 MB/s for writing ADATA vs. Seagate.
I also compared USB-thumb-drives against above Seagate 1 TB hard drive in Hard-Disk and USB Drive Speed Comparisons. Read times were comparable (100-200 MB/s), while for writing the Seagate drive was roughly 4 to 5-times faster (100 MB/s vs 20 MB/s).
Hard drives speeds and prices in 2013 are given in Harddisk Drive Speed in MB/s. Read speeds are roughly 200 MB/s for enterprise drives.
Now the read- and write-speeds of the SSD in the Dell XPS 13 9350 are quite astonishing: up to 1.5 GB/s for reading, 532 MB/s for writing. Even if you use LUKS/dm-crypt the values are 840 MB/s for reading, and 428 MB/s for writing. Below are the measurements using gnome-disk-utility.
Below is a short overview of small scale computers for use in embedded computing.
- Intel Galileo, single core Quark/Pentium, ca. 100 USD, <15 W
- Intel Edison, dual core Atom Silvermont, 500 MHz, ca. 100 USD, <1 W
- Raspberry Pi, single core ARM, 700 MHz, ca. 35 USD, ~1 W
- Arduino series, e.g., Intel Quark/Cortex, 32 MHz, ca. 15 USD, ~1 W
- ESP8266 (spec), single core Tensilica Xtensa LX106, 80 MHz, 7 USD, 1 mW
On the other end of the spectrum there are Mini PCs.
- Intel NUC, quadcore Intel i5/i7, ca. 400 USD (no SSD+no RAM), 6-60 W
- Apple Mac Mini, Intel i5/i7, ca. 500 USD, 6-85 W
- Apple Mac Pro, Intel 3.5 GHz 6-Core Intel Xeon E5, ca. 4,000 USD, <450 W
Now comes the fun part: connecting many small scale computers to a cluster.
Connecting 64 Raspberry Pi running MPI and putting them all into a Lego frame, see Raspberry Pi at Southampton.
Clustering 48 PandaBoards and putting this all into an industrial trashcan, see Phoronix: Building A 96-Core Ubuntu ARM Solar-Powered Cluster.
Clustering ten Intel NUCs each with 10GB RAM: Orange Box, see The Orange Box: Cloud for the Free Man, motto: Most planes fly in clouds…this cloud flies in planes!
Mac Pros are offered in the cloud, see Dedicated Mac Pro server hosting.