On 15-11-23 10:03 AM, Alexei Starovoitov wrote: > On Mon, Nov 23, 2015 at 05:11:58PM +0100, Hannes Frederic Sowa wrote: >> >> Actually, that is the reason why I mentioned it, so *the admin* can see >> something is going on. Do you want to protect ebpf from root? Skynet? ;) > > correct. To me both root and non-root are users in the first place and > they both shouldn't be allowed to misuse it. > >> In my opinion the kernel never should hide any information of the admin >> if they are accessible easily. Sampling the number of failed updates to >> a map or printing it via procfs/ebpffs seems to be just a matter of how >> difficult it should be done. The map has a lock, so the number is fairly > > map_lookup is actually lockless. It's a critical path and should be > as fast as possible. No extra stats just for debugging. > >> accurate. Sampling and plotting size of hash maps without having kprobes >> installed would be a nice thing, because it reduces complexity and this >> is nice to have. > > doing 'cat' from procfs is, of course, easier to use, but it's an extra > code that permenanetly lives in memory, whereas kprobe+bpf is a run-time > debugging.
Hopefully not jumping in off-base here (I've read most the thread), but what I've been doing is loading programs with debug ebpf code in them to keep a statistics map(s) and then I read that from userspace for stats. It works pretty well and lets me compile out the debug code when I want and also doesn't need kprobe at all. Also I can implement sampling so that the debug code only runs every .01% or something like that so it can be used in "real" systems. My "real" systems are just a couple node test setup but it seems to be ok ;) .John > > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
