mjb

42 ms·

391.
by mjb 11y ago
Yes. The techniques are possible (though have slightly different tactics) on other architectures. I'm aware of ROP being used for exploits on x86, ARM, MIPS and PPC.
392.
by mjb 11y ago
Thanks. That sounds like extremely interesting research. Being able to say things about liveness relative to probability of failure (or the distribution of probability of failure) would be very interesting.
393.
by mjb 11y ago
Extremely cool stuff. Questions for the researchers, if they are reading: - Does this proof cover any liveness concerns (weak fairness, deadlock freedom, etc) in addition to the safety property of linearizability? - If not, what would it ta
394.
CALISDO: Threat Modeling for Distributed Designs(brooker.co.za)
7 points by mjb 11y ago|0 comments
395.
by mjb 11y ago
Exactly. CAP is one of the borders of the space. It's popular because it's relatively easy to look at a claim and see if it's on the "possible" or "impossible" side of the border. Tools like that (as in yo
396.
by mjb 12y ago
Read section 3 and 4 of the whitepaper - the whole trust a quorum model is directly aimed at Sybil-style attacks. The key argument here is that the way they do group membership prevents these attacks by using a trusted quorum. This seems li
397.
How Amazon Web Services Uses Formal Methods(cacm.acm.org)
3 points by mjb 12y ago|0 comments
398.
by mjb 12y ago
Very good post. The two meanings of "consistent", and the generally different ways database literature and distributed systems literature approach the world, are a really common source of confusion. One way out of the confusion is
399.
by mjb 12y ago
> We are now entering deep (classified?) radar and ECM and EECM stuff. I doubt that this particular technique is classified, it is fairly well known and dates back to the early days of EW. One interesting angle is that the basic techniqu
400.
by mjb 12y ago
This is a very cool demo. There are a couple of ways to improve this technique, improve accuracy, reduce power, and improve noise rejection. The biggest wins are in improving the waveform from this one (called "continuous wave" or
401.
by mjb 12y ago
This simple demo wouldn't be very good at noise rejection, but the general idea could be extended to reject noise very well. One option is to use a wider-band signal, like a pulse or a chirp. Signal processing techniques could then be
402.
Electoral Trouble in Sybilania(brooker.co.za)
4 points by mjb 12y ago|0 comments
403.
by mjb 12y ago
> The obvious question for anything that claims to solve Byzantine consensus is: what about Sybil attacks? Not really answering your question (which is answered elsewhere in the thread), but these things are independent in an interesting
404.
by mjb 12y ago
We use it at Amazon Web Services ( http://research.microsoft.com/en-us/um/people/lamport/tla/am... ) and have found it very practically useful.
405.
by mjb 12y ago
I'm the same 'mjb' from the linked lobste.rs thread. If anybody is interested I expanded that comment into a blog post here: http://brooker.co.za/blog/2014/11/15/exactly-once.html The core
406.
by mjb 12y ago
It's amazing how much the Jepsen posts have raised the bar around distributed database testing. "Passes Jepsen" seems to be rapidly becoming required for open-source distributed databases. It's a great improvement, and I
407.
by mjb 12y ago
Yes, absolutely. That can be done using the global state (i.e. calling rand() or random()), or is probably better done by pulling from the system entropy pool (via /dev/urandom on Linux).
408.
by mjb 12y ago
I left the random_r numbers with single threads out of the post for exactly this reason. Performance with random_r on a single thread was less than 3% faster, with a slightly higher variance (which I can't explain, to be honest).
409.
by mjb 12y ago
Can you explain more? My understanding (which seems to be backed up by the implementation) is that I can call initstate_r in each thread to initialize thread-local state, then call random_r without synchronization from each thread as long a
410.
by mjb 12y ago
If you're interested, here's some other interesting reading in this area: * Castro and Liskov, "Practical Byzantine Fault Tolerance", http://www.pmg.lcs.mit.edu/papers/osdi99.pdf As the title says,
411.
Two Farmers and Common Knowledge(brooker.co.za)
10 points by mjb 12y ago|1 comments
412.
by mjb 12y ago
> you can never go from strong consistency down to an eventually consistent system Sure you can. In fact, almost every eventually consistent database is built on a collection of strongly consistent single systems. Eventually consistent s
413.
Ice Cream and Distributed Systems(brooker.co.za)
90 points by mjb 12y ago|5 comments
414.
by mjb 12y ago
Crash-only software is a great concept, and this article is a very interesting summary of what it is (and what it's not). If you read only one section of Candea and Fox's paper, I would recommend section 3 "Properties of Cras
415.
by mjb 12y ago
From a linked article: http://www.washingtonpost.com/blogs/wonkblog/wp/2014/03/28/t... > After Prohibition, beer makers were actually forbidden from putting alcohol content information on th
416.
by mjb 12y ago
Cool story! > Modern radars sample at 50 MHz, giving a 3m inter-sample distance. Getting that 50 MBytes/sec data down a 19.2k bits/sec channel was a challenge Surely you would do the processing for target extraction on the rada
417.
The Essential Barbara Liskov(brooker.co.za)
8 points by mjb 12y ago|0 comments
418.
by mjb 12y ago
Daniel Abadi's PACELC addresses exactly this: http://cs-www.cs.yale.edu/homes/dna/papers/abadi-pacelc.pdf By separating the behavior under failure (Consistency or Availability) and the behavior without f
419.
by mjb 12y ago
> 1) How do you model the myriad fault types that could possibly occur in distributed systems? You need to think at the right level of abstraction. Are packet loss and reordering really different faults? Are packet loss to a node and the
420.
CAP and PACELC: Thinking More Clearly About Consistency(brooker.co.za)
4 points by mjb 12y ago|0 comments

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