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How multi-disk failures happen
Having seen this failure mode happen a couple times now, it's time to share. Yes, Virgil, multi-disk failures DO happen during RAID rebuilds. I have pictures, so it MUST be true!First,
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The latest blog posts to take off on Hacker News. 85 posts.
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Speeding up HTTP with minimal protocol changes
As SPDY works its way through IETF ratification I began wondering whether it was really necessary to add a complex, binary protocol to th...
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Forcing the CPU affinity can make a monothreaded process run 2-3x faster
Today, I chrooted in my system from sysresCD and I discovered that running eix-update (a gentoo portage indexing program) ran almost 3x fas...
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Android Performance Case Study
Measure frame time, allocations, overdraw, and repeated work before changing code; the useful optimization is the one a trace can prove.
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GNU grep is 10x faster than Mac grep
That's likely all you need to do to install and make default GNU grep, which on my machine is a ~10x speedup over the grep that ships with Mac OS.
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Life of an instruction in LLVM
LLVM is a complex piece of software. There are several paths one may take on the quest of understanding how it works, none of which is simple. I recently had to dig in some areas of LLVM I was not previously familiar with, and this article is one of the outcomes of this quest.
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Java's Atomic and volatile, under the hood on x86
It’s well known that volatile in Java doesn’t mean the same thing as atomic . As Jeremy Manson says :
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3 billion items in Java Map with 16 GB RAM
One rainy evening I meditated about memory managment in Java and how effectively Java collections utilise memory. I made simple experiment, how much entries can I insert into Java Map with 16 GB of RAM?
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The little ssh that (sometimes) couldn't
Preface This is a technical article chronicling one of the most interesting bug hunts I’ve had the pleasure of chasing down. At AdGear Technologies Inc. where I work, ssh is king. We use it for management, monitoring, deployments, log file harvesting, even some event streaming. It’s solid, reliable, has all the…
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This Is Why They Call It a Weakly-Ordered CPU
On this blog, I’ve been rambling on about lock-free programming subjects such as acquire and release semantics and weakly-ordered CPUs. I’ve tried to make these …
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Understanding Postgres Performance
Update theres a more recent post that expands further on where to start optimizing specific queries, and of course if you want to dig into optimizing your infrastructure High Performance PostgreSQL is still a great read For many application developers their database is a black box. Data goes in, comes back out and in…
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Rethinking caching in web apps
Having spent a lot of the last few years worrying about the scalability of data-heavy applications like Rapportive , I have started to get the feeling that maybe we have all been “doing it wrong”. Maybe what we consider to be “state of the art” application architecture is actually holding us back.
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“iCloud Backup”
Last year, I bought my 87-year-old grandfather an iPad 2 to replace the who-knows-what PC that was frustrating him constantly. He only used the PC for email and playing music, so it was a no-brainer.
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Apple's HTTP POST caching is a bug
One of the changes in Apple’s release of iOS6 last week was a surprising new ability to cache POST responses.
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The Linux Graphics Stack
This is an introductory overview post for the Linux Graphics Stack, and how it currently all fits together. I initially wrote it for myself after having conversations with people like Owen Taylor, Ray Strode and Adam Jackson about this stack. I had to go back to them every month or so and learn the stuff from the…
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Introducing Qubes 1.0 ("a stable and reasonably secure desktop OS")
After nearly three years of work, I have a pleasure to announce that Qubes 1.0 has finally been released! To see the installation instructio...
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How ZFS continues to be better than Btrfs.
ZFS keeps winning over btrfs on many fronts. Here's a short list that explains exactly how.
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OS X Mountain Lion: Data Loss via 'Save As'
Update Dec 20, 2012 : Apple appears to have fixed this in a way by adding a “Keep changes in original document” checkbox in the save dialog. Bandaids are better than nothing. It is also possible to add a keyboard shortcut for Save As, which is partially hidden (option key).
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Implementing Fast Interpreters
Many modern virtual machines include either a fast interpreter or a fast baseline compiler. A baseline compiler needs extra memory and is li...
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Computed goto for efficient dispatch tables
Recently, while idly browsing through the source code of Python, I came upon an interesting comment in the bytecode VM implementation ( Python/ceval.c ) about using the computed gotos extension of GCC [1] . Driven by curiosity, I decided to code a simple example to evaluate the difference between using a computed goto…