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Ilmari Heikkinen
7,454 followers -
Doin' stuff
Doin' stuff

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New CPUs
Lots of cores! More cores! AMD bringing 32-core EPYC to the desktop, Intel bringing top-end 28-core Xeons to the desktop. In terms of compute, it's getting pretty interesting! 32 cores at 4 GHz and SIMD + ispc to SPMD it up. With 8-wide SIMD and 1 cycle FMA...
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AICoin
It takes a bit longer for your computer to return to the idle state. More and more of your applications seem to be spinning up the GPU. Background maintenance tasks seem to be slightly heavier. You receive an email with the details to access an AICoin walle...
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Commuting thoughts
The dubious benefit of a half hour commute is that you have some time to think about random things. Like, would dolphins and dogs have very precise concepts for things that are not readily understandable by us. Concepts related to their environments and phy...
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WAN OpenVPN at 915 Mbps
$ iperf -c remote -P4
...
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-10.0 sec 284 MBytes 238 Mbits/sec
[ 3] 0.0-10.0 sec 278 MBytes 233 Mbits/sec
[ 6] 0.0-10.0 sec 275 MBytes 230 Mbits/sec
[ 5] 0.0-10.1 sec 259 MBytes 216 M...
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Investments, debrief
Investments, I got a stable well-paid 7-month contract post-divorce and used most of the income to buy stocks. However, my portfolio balancing was ahem, shite. The two biggest investments in my portfolio cratered spectacularly (one was Globo Plc, an outrigh...
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Compute-NVMe
So there's this single-socket EPYC TYAN server with 24 NVMe hotswap bays . That's... a lot of NVMe. And they're basically PCIe x4 slots. What if you turned those NVMe boxes into small computers. Beefy well-cooled ARM SoC with 32 gigs of RAM and a terabyte o...
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OpenVPN over fast(er) links
Tested OpenVPN with 65k tun-mtu on the IPoIB network. It does 5-6 Gbps, compared to the 20-25 Gbps raw network throughput. I was surprised it managed 6 Gbps in the first place. "Oh what did I break now, why does my test run at 6 Mbps ... oh wait, that's Gbp...
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rdma-pipe
Haven't you always wanted to create UNIX pipes that run from one machine to another? Well, you're in luck. Of sorts. For I have spent my Saturday hacking on an InfiniBand RDMA pipeline utility that lets you pipe data between commands running on remote hosts...
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IO limits
It's all about latency, man. Latency, latency, latency. Latency drives your max IOPS. The other aspects are how big are your IOs and how many can you do in parallel. But, dude, it's mostly about latency. That's the thing, the big kahuna, the ultimate limit....
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RDMA cat
Today I wrote a small RDMA test program using libibverbs. That library has a pretty steep learning curve.  Anyhow. To use libibverbs and librdmacm on CentOS, install rdma-core-devel and compile your things with -lrdmacm -libverbs. Timings below, my test set...
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