Date: Mon, 09 Mar 2015 11:30:41 -0400 From: John Baldwin <jhb@freebsd.org> To: Sergey Kandaurov <pluknet@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Roger Pau =?ISO-8859-1?Q?Monn=E9?= <royger@freebsd.org> Subject: Re: svn commit: r279699 - in head/sys: amd64/amd64 i386/i386 Message-ID: <3050157.0anzMatu84@ralph.baldwin.cx> In-Reply-To: <CAE-mSOKhuTm-cRdHOvQ4E8EE5jjfae1QMEnjh1KZQgtQRGtb4g@mail.gmail.com> References: <201503062034.t26KYSP2063973@svn.freebsd.org> <CAE-mSOKhuTm-cRdHOvQ4E8EE5jjfae1QMEnjh1KZQgtQRGtb4g@mail.gmail.com>
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On Saturday, March 07, 2015 12:55:06 AM Sergey Kandaurov wrote: > On 6 March 2015 at 23:34, John Baldwin <jhb@freebsd.org> 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); > > There are another two similar cases at sys/i386/xen/mp_machdep.c > Both look like a no-op: static global never gets written data, > the condition is never satisfied. > I guess these variables can be safely reduced for clarity there: > hyperthreading_cpus, hyperthreading_cpus_mask under i386/xen. Yes, that file is rotted a bit. I think it is for a mode of Xen that Xen doesn't intend to support in the future and that it will be dropped from our tree altogether at some point? Roger probably has a better feel on this? -- John Baldwin
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