Date: Mon, 23 Nov 2020 07:17:50 +0200 From: Lari Sihto <lari.sihto@gmail.com> To: "Kevin P. Neal" <kpn@neutralgood.org> Cc: freebsd-questions@freebsd.org Subject: Re: kernel threads Message-ID: <CAA-cghWSzYj-d-pkXUbZvXQZB5Ozd1VbhXz6X=dryXhSfDSMPw@mail.gmail.com> In-Reply-To: <X7rfngQzAIJjxw7X@neutralgood.org> References: <CAA-cghUBT1ZSMqE7HoR%2BCDBsm7zjBTyE3KM4AeOmJ_V_GOnTmw@mail.gmail.com> <X7rfngQzAIJjxw7X@neutralgood.org>
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Yes, that's it. Do you know why the top half is allowed to sleep but the bottom half is not? ma 23. marrask. 2020 klo 0.01 Kevin P. Neal (kpn@neutralgood.org) kirjoitti: > On Sun, Nov 22, 2020 at 09:59:57PM +0200, Lari Sihto wrote: > > Hi, just wondering if there is some technical or philosophical reason as > to > > why the freebsd operating system doesn't seem to use kernel-space threads > > like some other unix-like operating systems do. To my knowledge the need > > for kernel threads arises when the kernel code needs to sleep in kernel > > which one cannot do. Kernel threads seem to fix that problem. Have been > > wondering this for a long time and I hope someone here knows the > reasoning > > behind this implementation detail be it just performance related or > > something along the line of "no-one just haven't been up to implementing > > that kind of a functionality"? > > Are you thinking of something different than what is described in the > kthread(9) and kproc(9) man pages? > > Also, my limited understanding is that the "top" half of the kernel is > allowed to sleep, but the "bottom" half is not. > > You'll get more informed responses to this topic on the freebsd-arch, > freebsd-hackers, or maybe freebsd-current lists. Very few if any kernel > hackers hang out on this list. > > -- > Kevin P. Neal http://www.pobox.com/~kpn/ > "Not even the dumbest terrorist would choose an encryption program that > allowed the U.S. government to hold the key." -- (Fortune magazine > is smarter than the US government, Oct 29 2001, page 196.) >
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