Adrian Chadd wrote: > anyone have any recent information about this? some people say "HT > sucks for almost all workloads", others say "recent scheduler > improvements make HT more useful".. is there anything reasonably > authoritative?
No, because it depends on your applications and workload. for some it is better, for some it is not. Therefore it's best you try both variants on your own machine with your own applications and measure the difference. There's one rule of thumb, however: If you only have one HTT-capable processor, then a UP kernel will almost always be the better option, because the locking overhead of an SMP kernel will probably outweigh any advantages of HTT. On the other hand, if you have a real SMP system (i.e. multiple processors or cores, not counting HTT), then you will want to use an SMP kernel anyway. In that case, enabling HTT will probably not hurt -- _but_ there have been reports of some people that HTT hurts in such a case for certain kinds of applications (I think databases was one of them, but I don't remember exactly). Anyway, there are exceptions to any rule, so you should measure yourself. Personally I disable HTT on all of my machines because of the security issue (jails do _not_ help here at all!), and speed improvements -- if any -- are marginally small, according to my own measurements. In fact I had a hard time finding any reproducible measurable improvements at all for my typical workloads; consequently my decision was governed by the security issue. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M. Handelsregister: Registergericht Muenchen, HRA 74606, Geschäftsfuehrung: secnetix Verwaltungsgesellsch. mbH, Handelsregister: Registergericht Mün- chen, HRB 125758, Geschäftsführer: Maik Bachmann, Olaf Erb, Ralf Gebhart FreeBSD-Dienstleistungen, -Produkte und mehr: http://www.secnetix.de/bsd "Perl will consistently give you what you want, unless what you want is consistency." -- Larry Wall _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "[EMAIL PROTECTED]"
