Viewing profile — davidtgoldblatt

It kinda depends; you only do the membarrier when you're about to sleep anyways, and the non-expedited membarrier() call is just a synchronize_rcu(), so it's not that drastically m…

There's two I've tried to do this: - On the wait side, do the CAS to set the "waiter present" bit. Down unlock, do a (relaxed) read of the lock word, and if "waiter present" isn't …

> There's clearly an opportunity for a much longer talk, this teases that Paul (McKenney, of Linux fame) will have a very different take and we don't hear what it is, maybe that wa…

> Maybe there is a way to paper over this in the glibc implementation of free_sized (rather than calling free unconditionally), and still do something useful for the glibc allocato…

My usages are similar to yours, but new C standards still benefit me because I can opportunistically detect and make use of new features in a configure script. To use my baby as an…

Of particular interest is section 20.18 -- "Mirroring memory operands"; extending (something like) register renaming to memory.

> Maybe there's some reason this doesn't work, or maybe the performance improvements aren't worth the effort? I work on an allocator, and I've lobbied (Linux) kernel people for thi…

I can't imagine how pissed off I'd be if I survived a nuclear winter and traveled hundreds of miles to read the prophesied guidestones that could save us all, only to find out that…

Example usage on some code with interesting pipelining + resource contention properties: https://godbolt.org/z/11oyav (The code is from the stream vbyte repo; see https://lemire.me…

Depending on what exactly you mean by "hand it a block of memory to manage", you can do this with jemalloc's extent hook functionality. Though that's meant for "I have some long-li…

Oh yes; while certainly mismatched new[]/delete has been a source of problems since forever, what I mean specifically is the new types of exploits possible with the "operator delet…

Another fun attack vector that I don't think has been well explored yet involves the use of C++ sized deallocation functions. If a base class is missing a virtual destructor, or if…

(As background, I'm a jemalloc developer; reposting my twitter comment on the same article): This is quite a bad way of doing a malloc benchmark -- getting realistic activity patte…

It's implementable with a kernel driver on Solaris because of its scheduling hooks. (This was done in the "Mostly Lock-Free Malloc" paper).

My experience working on an OSS project has been that the biggest thing missing from the bug-reporter side isn't phrasing or planning, just dedication. If someone doesn't post a us…

All the volume 4A listings are in MMIX, and there's "The MMIX Supplement" by Martin Ruckert, redoing the first three volumes in MMIX, which I believe is regarded as the authoritati…

tl;dr for people familiar with the C/C++11 MM: It's very similar. `relaxed` -> `Opaque`, `seq_cst` -> `volatile`. `acquire` and `release` map more or less the same. Interestingly, …

I think you're on the right track (i.e. viewing it as a permutation, and looking at the cycle decomposition of that permutation). Try indexing from 0 instead of 1 if you're not. Th…

It's part of the core language semantics (arguably the core language semantics) for Java2K ( http://p-nand-q.com/programming/languages/java2k/ ).

Here's a fun related issue: A common Linux mutex-implementation strategy to deal with this issue (waker-waiter races) is by releasing a mutex before futex-waking any threads blocke…

Hah, I think I'm that person you're referring to. I would characterize my response differently. Stripping out the specifics, the problem was: "write some code that blocks until one…

I don't totally follow the conclusion you're trying to draw w.r.t. the definition of a patent troll; clearly there's a lot of people who think that filing and then attempting to en…

Saying that "patent troll" is synonymous with "NPE" is more restrictive than its common usage; for example, wikipedia defines it as "a person or company that attempts to enforce pa…

An anecdote for those who hoped they'd find suggestions in the comments: I ended up buying some over-the-head earmuff headphones aimed at construction workers (I think with a 25dB …