On Mon, Jan 28, 2019 at 4:12 PM Alexander Popov <alex.popov@xxxxxxxxx> wrote: > > On 23.01.2019 14:03, Kees Cook wrote: > > This adds a new plugin "stackinit" that attempts to perform unconditional > > initialization of all stack variables > > Hello Kees! Hello everyone! > > I was curious about the performance impact of the initialization of all stack > variables. So I did a very brief test with this plugin on top of 4.20.5. > > hackbench on Intel Core i7-4770 showed ~0.7% slowdown. > hackbench on Kirin 620 (ARM Cortex-A53 Octa-core 1.2GHz) showed ~1.3% slowdown. Thanks for looking at this! I'll be including my hackbench measurements for the v2 here in a moment. > This test involves the kernel scheduler and allocator. I can't say whether they > use stack aggressively. Maybe performance tests of other subsystems (e.g. > network subsystem) can show different numbers. Did you try? I haven't found a stable network test yet. If someone can find a reasonable workload, I'd love to hear about it. > I've heard a hypothesis that the initialization of all stack variables would > pollute CPU caches, which is critical for some types of computations. Maybe some > micro-benchmarks can disprove/confirm that? I kind of think micro-benchmarks aren't so useful because they don't represent a real-world workload. I've heard people talk about SAP-HANA as a good test, but I can't get my hands on it. I wonder if anyone has tried "mysqlslap"? -- Kees Cook
