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Colin Percival

daemonology.net

Not on this site, but still likely to be of interest, is my Tarsnap online backup service .

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Security & Privacy 22Tech Industry & Business 21Infrastructure & DevOps 16Systems & Performance 12Software Engineering 7Life, Learning & Writing 6

1

How to zero a buffer

Now, we don't want to truly change the observable behaviour of our software — but fortunately the C standard has a more liberal concept of "observable" than most people. In particular, the C standard states that the observable behaviour includes accesses to volatile objects . What is a volatile object, you ask? It is…

2

FreeBSD/EC2 lives

There are some caveats to this. First, at the moment only FreeBSD 9.0-CURRENT can run under EC2; I haven't merged bug fixes back to the stable branches. Second, at the moment FreeBSD only runs on t1.micro instances, for reasons I can't discuss (NDA) but hope will be resolved soon. Third, this code hasn't received very…

3

The FreeBSD/Firecracker Platform

I started working on this on June 20th mainly out of curiosity: I had heard that Firecracker had PVH boot support (which was in fact mistaken!) and I knew that FreeBSD could boot in PVH mode from Xen, so I wondered just how hard it would be to get FreeBSD up and running. Not impossible, as it turned out, but a bit…

4

Some thoughts on Spectre and Meltdown

The story of these attacks starts in late 2004. I had submitted my doctoral thesis and had a few months before flying back to Oxford for my defense, so I turned to some light reading: Intel's latest "Optimization Manual", full of tips on how to write faster code. (Eking out every last nanosecond of performance has…

6

FreeBSD/EC2 on C5 instances

Ever since the first EC2 instances launched — the ones which were retrospectively named "m1.small" — Amazon has relied on the Xen hypervisor. No longer: C5 instances use KVM. This sounds like it would be a problem, but in fact that change didn't bother FreeBSD at all: Now that everything uses hardware-based paging…

10

EC2 Boot Time Benchmarking

Once I finished writing ec2-boot-bench, the natural next step was to run some tests — in particular, to see how FreeBSD compared to other operating systems used in EC2. I used the c5.xlarge instance type and tested FreeBSD releases since 11.1-RELEASE (the first FreeBSD release which can run on the c5.xlarge instance…

11

FreeBSD on the Graviton 3

As far as FreeBSD is concerned, Graviton 3 is mostly just a faster version of the Graviton 2: Most things "just work", and the things which don't work on Graviton 2 — hotplug devices and cleanly shutting down an instance via the EC2 API — also don't work on Graviton 3. (Want to help get these fixed? Sponsor my work on…