Messages in this thread | | | From | Nicolai Stange <> | Subject | [PATCH v4 0/2] reduce TSC deadline frequency errors | Date | Thu, 14 Jul 2016 17:22:53 +0200 |
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The v3 series can be found at
http://lkml.kernel.org/g/20160713130344.8319-1-nicstange@gmail.com
Applicable to linux-next-20160708 (in case you wonder why I turned back from the 20160712 given in v3 to 20160708 again: mysteriously, 20160712 doesn't boot neither w/ nor w/o this series anymore).
The individual patches don't depend on each other.
Changes to v3: As Paolo Bonzini pointed out in reply to v3, for the values of 2, 4 and 8 of TSC_DIVISOR, the 64 bit division (u32)(((u64)tsc_khz * 1000) / TSC_DIVISOR) can be safely turned into a 32 bit division by changing associativity: tsc_khz * (1000 / TSC_DIVISOR)
In doing so, it suggests itself to squash former [1/3] ("arch, x86, tsc deadline clockevent dev: reduce frequency roundoff error") and [2/3] ("arch, x86, tsc deadline clockevent dev: reduce TSC_DIVISOR to 2") into a single patch. Furthermore, reducing TSC_DIVISOR down to 2 becomes unnessecary -- setting it to 8 suffices already.
Thus, - [1/2] ("arch, x86, tsc deadline clockevent dev: eliminate frequency roundoff error") Former [1/3] and [2/3] squashed together. Don't reduce TSC_DIVISOR to 2 but to 8 only. Change associativity in order to get rid of the 64 bit division. Adapt the commit message accordingly. - [2/2] ("arch, x86, tsc: inform TSC deadline clockevent device about recalibration") Former [3/3]. Likewise change associativity in order to get rid of the 64 bit division here, too.
Changes to v2: - [3/3] ("arch, x86, tsc: inform TSC deadline clockevent device about recalibration") Use clockevents_update_freq() rather than clockevents_config().
- Former [4/4] ("kernel/time/clockevents: compensate for monotonic clock's dynamic frequency") Split off, not a member of this series anymore.
Changes to v1: - [1/3] ("arch, x86, tsc deadline clockevent dev: reduce frequency roundoff error") No changes to the patch. Note that the v1 mail could not be delivered to the author of the TSC_DIVISOR introducing commit 279f1461432c ("x86: apic: Use tsc deadline for oneshot when available"), Suresh Siddha <suresh.b.siddha@intel.com>, so I had to remove him from the CC list.
- [2/3] ("arch, x86, tsc deadline clockevent dev: reduce TSC_DIVISOR to 2") Likewise.
- [3/3] ("arch, x86, tsc: inform TSC deadline clockevent device about recalibration") Silence the kbuild test robot on ARCH=i386 by wrapping the new call to lapic_update_tsc_freq() from arch/x86/kernel/tsc.c in an #ifdef CONFIG_X86_LOCAL_APIC.
Nicolai Stange (2): arch, x86, tsc deadline clockevent dev: eliminate frequency roundoff error arch, x86, tsc: inform TSC deadline clockevent device about recalibration
arch/x86/include/asm/apic.h | 1 + arch/x86/kernel/apic/apic.c | 28 ++++++++++++++++++++++++++-- arch/x86/kernel/tsc.c | 6 ++++++ 3 files changed, 33 insertions(+), 2 deletions(-)
-- 2.9.0
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