Re: [bitfolk] rngd using high cpu

Hello, On Tue, Sep 01, 2020 at 04:47:41PM +0100, Hugh Frostick wrote: - principally has Dovecot) which has this process using 60-95% cpu: I've no idea what is wrong with your rngd, but BitFolk has some hardware entropy devices which you can use so you don't need to fake it with rngd. https://tools.bitfolk.com/wiki/Entropy#BitFolk.27s_entropy_service (The rest of this article needs rewriting in light of subsequent changes to Linux's random subsystem, but the instructions for the entropy service are accurate for Debian/Ubuntu.) Is ekeyd-egd-linux available for CentOS? May I ask why you are using rngd? AFAIK on modern Linux everything should be pointed at /dev/urandom which will never block except possibly at early boot time. People have been using things like rngd and haveged to get past the early stall. Is that why you have been using it or is there some other reason? Having sdaid that, I did some experiments last year with a Debian buster VM and unless I disable the RDRAND CPU instruction is gets entropy pretty quickly (1.14 seconds vs 48.88s): http://strugglers.net/~andy/blog/2019/07/11/experiments-with-rdrand-and- entropykey/ So is the boot stage even an issue? I think that you should only see boot time entropy starvation on a BitFolk VM if you purposefully disable RDRAND¹. Cheers, Andy ¹ e.g. because you believe it is a black box made by Intel at the behest of the NSA