sprachspiel

Just tested a i4i.32xlarge:

  $ lsblk
  NAME         MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
  loop0          7:0    0  24.9M  1 loop /snap/amazon-ssm-agent/7628
  loop1          7:1    0  55.7M  1 loop /snap/core18/2812
  loop2          7:2    0  63.5M  1 loop /snap/core20/2015
  loop3          7:3    0 111.9M  1 loop /snap/lxd/24322
  loop4          7:4    0  40.9M  1 loop /snap/snapd/20290
  nvme0n1      259:0    0     8G  0 disk 
  ├─nvme0n1p1  259:1    0   7.9G  0 part /
  ├─nvme0n1p14 259:2    0     4M  0 part 
  └─nvme0n1p15 259:3    0   106M  0 part /boot/efi
  nvme2n1      259:4    0   3.4T  0 disk 
  nvme4n1      259:5    0   3.4T  0 disk 
  nvme1n1      259:6    0   3.4T  0 disk 
  nvme5n1      259:7    0   3.4T  0 disk 
  nvme7n1      259:8    0   3.4T  0 disk 
  nvme6n1      259:9    0   3.4T  0 disk 
  nvme3n1      259:10   0   3.4T  0 disk 
  nvme8n1      259:11   0   3.4T  0 disk

Since nvme0n1 is the EBS boot volume, we have 8 SSDs. And here's the read bandwidth for one of them:

  $ sudo fio --name=bla --filename=/dev/nvme2n1 --rw=read --iodepth=128 --ioengine=libaio --direct=1 --blocksize=16m
  bla: (g=0): rw=read, bs=(R) 16.0MiB-16.0MiB, (W) 16.0MiB-16.0MiB, (T) 16.0MiB-16.0MiB, ioengine=libaio, iodepth=128
  fio-3.28
  Starting 1 process
  ^Cbs: 1 (f=1): [R(1)][0.5%][r=2704MiB/s][r=169 IOPS][eta 20m:17s]

So we should have a total bandwidth of 2.7*8=21 GB/s. Not that great for 2024.

This is for 8 SSDs and a single modern PCIe 5.0 has better specs than this.

These settings control writing back modified pages. The experiments in the paper are read-only. With writes the situation is even worse than shown in the paper (though tuning these settings may help a bit).

This would be exactly the kind of innovation we would need in computer science. Instead we often get stuck in local minima (in this case a 40-year old POSIX interface) without realizing how much pain this causes.

Even after watching these videos and reading lots of articles on the topic, I still find the full C++ memory model extremely hard to understand. However, on x86 there are actually only a couple of things that one needs to understand to write correct lock free code. This is laid out in a blog post: https://databasearchitects.blogspot.com/2020/10/c-concurrenc...

Everyone interested in the history of computing should read The Dream Machine by M. Mitchell Waldrop. The book pretends to be the biography by a little-known, but highly-influential guy named Licklider, but is in fact maybe the best general history of computing. It covers Turing, von Neumann, ARPA, Multics, DARPA (the internet), and Xerox PARC. Alan Key recommends it as the best history of PARC.

Well, the biggest Ivy Bridge EX has 15 cores! There's speculation that the 18 core Haswell-EPs are actually Haswell-EX dies that Intel wants to get rid as fast as possible because these chips have buggy TSX (transactional memory).

fruit

But cold caches are an unrealistic assumption. The top-most levels of a tree will always be in cache, unless you almost never access them -- in which case there's no problem either. Additionally, a radix tree is ordered, whereas a hash table is not.

I wonder how long it will take until there is a market for IP addresses. I suspect once such a market is in place IPv6 will not see widespread adoption, since most IPv4 addresses are not really used.

What has happened so far: A curfew was put in place, it has done absolutely nothing, the streets are full of people everywhere in the country. There are reports of dozens of deaths. The headquarter of president Mubaraks party is on fire for hours, no firefighter are there. The headquarter is next the most important Egyptian museums. The police has no control over the streets, the army was ordered in to enforce the curfew. The people are actually cheering as the military is moving in. It is still unclear what the military will do. Hillary Clinton has issued a statement to the Egyptian government to restrain security forces and avoid violence.