On Monday 06 February 2006 14:46, Andrew Gallatin wrote: > Andre Oppermann writes: > > Andrew Gallatin wrote: > > > Why dooes machdep.cpu_idle_hlt=1 drop my 10GbE network rx > > > performance by a considerable amount (7.5Gbs -> 5.5Gbs)? > > <...> > > > This may be the same problem OpenBSD has fixed last year in the handling > > of the idle loop. From the kerneltrap posting: > > <....> > > > First commit message: > > http://marc.theaimsgroup.com/?l=openbsd-cvs&m=111692513727274&w=2 > > > > The MFC with all changes in one commit message: > > http://marc.theaimsgroup.com/?l=openbsd-cvs&m=111859519015510&w=2 > > The bug they fixes was missing interrupts by both calling APM's idle > routine, which may hlt, and hlt'ing in the idle loop itself. Since I > have no idea what acpi is doing, I got excited about this. > > Alas, it seems like this isn't it. I pointed cpu_idle_hook back to > cpu_idle_default and away from acpi_cpu_idle, but that made no > difference. You may be seeing problems because it might simply take a while for the CPU to wake up from HLT when an interrupt comes in. The 4BSD scheduler tries to do IPIs to wakeup any sleeping CPUs when it schedules a new thread, but that would add higher latency for ithreads than just preempting directly to the ithread. Oh, you have to turn that on, it's off by default (kern.sched.ipiwakeup.enabled=1). -- John Baldwin <jhb_at_FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.orgReceived on Mon Feb 06 2006 - 19:31:55 UTC
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