wait wait ~ can someone comment on this http://www.daemonology.net/hyperthreading-considered-harmful/ ?
is it still in vogue? On Fri, Mar 8, 2013 at 12:31 AM, David Ruggiero <thatseattle...@gmail.com> wrote: >>> "The OpenBSD kernel and network stack still do run only on CPU0, so if > all you plan to do is >>> use PF to filter traffic, then you are indeed better off disabling HTT." > > > Thanks. That's the piece of info I needed, as (at least per current plans) > 95% of the machine's time will be in PF-land, with few or no userland > programs besides the occasional log-muncher. > > I do understand the ruleset for PF has changed, and then changed again, in > the intervening years. I planned to start from scratch with my rules, not > try to port anything from the old system except as a "don't forget to allow > this" kind of reminder. > > thx D > > > > On Thu, Mar 7, 2013 at 8:51 PM, System Administrator <ad...@bitwise.net>wrote: > >> On 7 Mar 2013 at 20:24, David Ruggiero wrote: >> >> > I've been using OpenBsd for 8+ years on my main router/firewall (4 >> > NICs). >> > Time to upgrade (I'm back on v3.8, yikes). Past time, really. >> > So....lots to >> > learn / re-learn here. Have patience. First question: >> > >> > I'll be loading 5.2 on a low-power, Atom E640-based box (the Soekris >> > net6501). That chip has two Hyperthreading cores. Several >> > net-references >> > (esp. ca**mel.org ) advocate turning off HTT in the bios when using >> > OpenBSD >> > for faster interrupt servicing / task switching latency. >> > >> > But....perhaps that advice is pre-5.2, when we got pthreads(3) >> > support? >> > What's the best current advice for that kind of one-cpu, >> > multi-logical-thread system? >> > >> > 1) Single processor kernel or multi-processor (smp) kernel? >> > 2) If the latter, HTT turned on or off? >> > >> > Thanks. >> > Bonnie >> > >> > >> >> First thing first, read, read, and re-read the official documentation. >> Many things changed in the intervening years, in particular, PF >> configuration syntax has changed a fair bit. >> >> Do note that unlike the Linux world where you have to dig for third >> party "how-to"s, OpenBSD official documentation is very complete and up >> to date. Which is one of the reasons the website you referenced is >> frowned upon as most of its "information" is either out of date or >> simply wrong. That said, the particular point you bring up may still be >> valid -- much depends on your specific situation. >> >> Whether or not to use hyperthreading and multiprocessor (MP) kernel >> depends on the workload of your firewall. The OpenBSD kernel and >> network stack still do run only on CPU0, so if all you plan to do is >> use PF to filter traffic, then you are indeed better off disabling HTT. >> However, if your firewall is also going to be running a fair amount of >> userland processes (e.g. your website with db backend) then you may >> well benefit from multiprocessor support.
