On Mon, Mar 09, 2015 at 07:42:52PM +0200, Konstantin Belousov wrote: > On Fri, Mar 06, 2015 at 08:34:28PM +0000, John Baldwin wrote: > > Author: jhb > > Date: Fri Mar 6 20:34:28 2015 > > New Revision: 279699 > > URL: https://svnweb.freebsd.org/changeset/base/279699 > > > > Log: > > Only schedule interrupts on a single hyperthread of a modern Intel CPU > > core > > by default. Previously we used a single hyperthread on Pentium4-era > > cores but used both hyperthreads on more recent CPUs. > > > > MFC after: 2 weeks > > > > Modified: > > head/sys/amd64/amd64/mp_machdep.c > > head/sys/i386/i386/mp_machdep.c > > > > Modified: head/sys/amd64/amd64/mp_machdep.c > > ============================================================================== > > --- head/sys/amd64/amd64/mp_machdep.c Fri Mar 6 16:43:54 2015 > > (r279698) > > +++ head/sys/amd64/amd64/mp_machdep.c Fri Mar 6 20:34:28 2015 > > (r279699) > > @@ -828,8 +828,8 @@ set_interrupt_apic_ids(void) > > continue; > > > > /* Don't let hyperthreads service interrupts. */ > > - if (hyperthreading_cpus > 1 && > > - apic_id % hyperthreading_cpus != 0) > > + if (cpu_logical > 1 && > > + apic_id % cpu_logical != 0) > > continue; > > > > intr_add_cpu(i); > > > > Modified: head/sys/i386/i386/mp_machdep.c > > ============================================================================== > > --- head/sys/i386/i386/mp_machdep.c Fri Mar 6 16:43:54 2015 > > (r279698) > > +++ head/sys/i386/i386/mp_machdep.c Fri Mar 6 20:34:28 2015 > > (r279699) > > @@ -842,8 +842,8 @@ set_interrupt_apic_ids(void) > > continue; > > > > /* Don't let hyperthreads service interrupts. */ > > - if (hyperthreading_cpus > 1 && > > - apic_id % hyperthreading_cpus != 0) > > + if (cpu_logical > 1 && > > + apic_id % cpu_logical != 0) > > continue; > > > > intr_add_cpu(i); > > BTW, this sounds somewhat backward from the intention of the HTT/SMT. > The feature was aimed to reduce latency of memory or device registers > reads by allowing several contexts to stuck on the cache line fill > or waiting for the device response to read request. > > Since typical interrupt handler just EOIs the source or does nothing at > all to the source, what is the reasoning behind the change ?
typical interrupt handler do TCP work? _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "[email protected]"
