4 ms·
In a way this is a direct consequence of sharing. Almost any shared resource will have contention, or stored state and this will affect use of the resource by (
by bpye 8y ago
In a way this is a direct consequence of sharing. Almost any shared resource will have contention, or stored state and this will affect use of the resource by (typically) other cores/threads. This will always end up telling you something, you just have to hope it's nothing useful.
- ahartmetz 8y agoThe only ways to share without contention that I can think of are: - Static allocation (e.g. static partitioning of caches, actually exists in some architectures IIRC) - Some kind of ahead of time scheduling in a "sufficiently smart compiler", but then you can't dynamically run independent threads of execution on the shared resource You know what else is a contended shared resource in multicore computers? RAM. Space is kind of statically allocated but bandwidth / access / latency is very dynamic. At this point I wouldn't bet that it can't be exploited.
- Mirioron 8y ago>RAM. Space is kind of statically allocated but bandwidth / access / latency is very dynamic. At this point I wouldn't bet that it can't be exploited. Correct me if I'm wrong, but doesn't rowhammer basically do that?
- ahartmetz 8y agoRowhammer is different, it doesn't use a timing side channel. It uses an electrical(!) flaw to turn reads at address X into writes at address Y. It can work on a single core machine running a single process.
- bpye 8y agoStatic allocation pretty much means you aren't sharing the resource too. It is a sort of mitigation but you lose a lot of the performance benefit.