Skylar, So, 50% is used for processes and the other 50% to handle hardware interrupts. Is that right?
2006/8/30, Skylar Thompson <[EMAIL PROTECTED]>:
Jordi Carrillo wrote: > 2006/8/30, backyard <[EMAIL PROTECTED]>: >> >> >> >> --- Jordi Carrillo <[EMAIL PROTECTED]> wrote: >> >> > I've read that SMP should be disabled for >> > performance issues (I did not know >> > that before installing freebsd). I have a P4 3GHz >> > with hyperthreading >> > technology. I have the SMP-GENERIC kernel and it >> > only launches one cpu. So, >> > I've decided to disable SMP from BIOS. Is that ok?, >> > knowing that I have a >> > Smp enabled kernel? or should I install one without >> > smp? If so, is there a >> > way to install one already precompiled? >> > Thanks in advance >> > >> > -- >> > http://jordilin.wordpress.com >> > _______________________________________________ >> > freebsd-questions@freebsd.org mailing list >> > >> http://lists.freebsd.org/mailman/listinfo/freebsd-questions >> > To unsubscribe, send any mail to >> > "[EMAIL PROTECTED]" >> > >> >> if the system runs with one cpu now and you don't >> enable smp with HT with the sysctl variable then you >> should be ok. If your not doing SMP then recompiling >> the kernel for single processor mode will make things >> run a little quicker because the SMP code won't come >> into play. >> >> with HT disabling in FreeBSD is more for the security >> issues about a potential exploit whereby one process >> in one pipe can access the priveledged information of >> a process in another pipe because the two cores share >> one processor cache and thus one cache table. To my >> knowledge this hasn't been exploited yet. >> >> If you just install the generic kernel you it should >> be only the uniprocessor one. I would just do a: >> >> cd /usr/src && make buildworld && make >> KERNCONF=GENERIC buildkernel && make KERNCONF=GENERIC >> installkernel >> >> as opposed to a binary version assuming you haven't >> updated yet you won't have to install world but I >> believe it must have the build in the source tree to >> build a kernel. On your P4 though the difference >> between SMP and uniproc may not be worth the trouble >> because I don't think much of a gain would be made. on >> a P1 a much different story... >> >> if you aren't concerned with bad users or hackers >> hitting the box I would just enable HT with the sysctl >> variable. This will not make things run slower at all, >> just (in theory) less secure, which is why the >> veriable was created in the first place as I recall. >> If you are concerned I would wait until you update >> your system and then just build a GENERIC/CUSTOM >> kernel without the SMP option set. >> >> >> -brian >> > > > I will disable smp from bios. If I have a smp kernel, I suppose there > will > be no problem after all. Would that be ok? > The problem with having SMP enabled is that the smp kernel only > detects one > cpu and the system monitor only features one cpu as well as gkrellm (in > Linux it shows two cpus). When compiling the system monitor shows the > cpu at > a maximum of 50%, so what's going on with the other 50%? > writing machdep.hlt_logical_cpus to 2 in loader.conf does not solve > anything. I believe FreeBSD uses the other logical CPU to handle hardware interrupts, which can still help performance. You can check dmesg to see how it's actually handling it. -- -- Skylar Thompson ([EMAIL PROTECTED]) -- http://www.cs.earlham.edu/~skylar/
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