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x86/tsc: Clean up rdtsc helpers

Andy Lutomirski kvm linux-hams linux-input lkml virtualization 3 versions – In review

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Versions newest first · linked by author and title

  1. v3 Latest18 patches 19 repliesIn review
  2. v217 patches 13 repliesSuperseded
  3. v117 patches 0 repliesSuperseded

Changes in v3 from the cover letter

- Rename rdtsc_unordered to just rdtsc
- Get rid of rdtsc_barrier entirely instead of renaming it
- The KVM patch is new (see above)
- Added some acks

Patches in v3 No applies recorded yet

#Subject and filesSizeRepliesApplied
1/18x86/tsc: Inline native_read_tsc and remove __native_read_tscarch/x86/entry/vdso/vclock_gettime.c arch/x86/include/asm/msr.h arch/x86/include/asm/pvclock.h +4 more+9 -171 reply
2/18x86/msr/kvm: Remove vget_cycles()arch/x86/include/asm/tsc.h arch/x86/kvm/x86.c+1 -142 replies
3/18x86/tsc/paravirt: Remove the read_tsc and read_tscp paravirt hooksarch/x86/include/asm/msr.h arch/x86/include/asm/paravirt.h arch/x86/include/asm/paravirt_types.h +3 more+8 -514 replies
4/18x86/tsc: Replace rdtscll with native_read_tscarch/x86/boot/compressed/aslr.c arch/x86/include/asm/msr.h arch/x86/include/asm/tsc.h +11 more+22 -281 reply
5/18x86/tsc: Remove the rdtscp and rdtscpll macrosarch/x86/include/asm/msr.h+0 -90 replies
6/18x86/tsc: Use the full 64-bit tsc in tsc_delayarch/x86/lib/delay.c+4 -40 replies
7/18x86/cpu/amd: Use the full 64-bit TSC to detect the 2.6.2 bugarch/x86/kernel/cpu/amd.c+3 -30 replies
8/18baycom_epp: Replace rdtscl() with native_read_tsc()drivers/net/hamradio/baycom_epp.c+1 -15 replies
9/18staging/lirc_serial: Remove TSC-based timingdrivers/staging/media/lirc/lirc_serial.c+4 -590 replies
10/18input/joystick/analog: Switch from rdtscl() to native_read_tsc()drivers/input/joystick/analog.c+2 -20 replies
11/18drivers/input/gameport: Replace rdtscl() with native_read_tsc()drivers/input/gameport/gameport.c+2 -20 replies
12/18x86/tsc: Remove rdtscl()arch/x86/include/asm/msr.h+0 -30 replies
13/18x86/tsc: Rename native_read_tsc() to rdtsc()arch/x86/boot/compressed/aslr.c arch/x86/entry/vdso/vclock_gettime.c arch/x86/include/asm/msr.h +21 more+58 -491 reply
14/18x86: Add rdtsc_ordered() and use it in trivial call sitesarch/x86/entry/vdso/vclock_gettime.c arch/x86/include/asm/msr.h arch/x86/kernel/trace_clock.c +2 more+34 -400 replies
15/18x86/tsc: Use rdtsc_ordered() in check_tsc_warp() and drop extra barriersarch/x86/kernel/tsc_sync.c+6 -80 replies
16/18x86/tsc: In read_tsc, use rdtsc_ordered() instead of get_cycles()arch/x86/kernel/tsc.c+1 -10 replies
17/18x86/kvm/tsc: Drop extra barrier and use rdtsc_ordered in kvmclockarch/x86/include/asm/pvclock.h+12 -93 replies
18/18x86/tsc: Remove rdtsc_barrier()arch/x86/include/asm/barrier.h arch/x86/um/asm/barrier.h+0 -240 replies

Reviews trailers per patch

7 of 18 patches have a Reviewed-by or Acked-by.

PatchDmitry TorokhovThomas SailerBorislav PetkovPaolo Bonziniwalter harms
1/18A-b
2/18A-b A-b
3/18A-b
4/18A-b
5/18
6/18
7/18
8/18A-b A-b
9/18
10/18A-b
11/18A-b
12/18
13/18
14/18
15/18
16/18
17/18
18/18

Trailers given in replies are filled; those carried in the patches from earlier versions are outlined with dashes. Scroll the table sideways for all 5 reviewers.

Read the v3 thread

Cover letter [PATCH v3 00/18] x86/tsc: Clean up rdtsc helpers

My sincere apologies for the spam. I send an unholy mixture of the real patch set and an old poorly split-up patch set, and the result is incomprehensible. Here's what I meant to send.

After the some recent threads about rdtsc barriers, I remembered that our RDTSC wrappers are a big mess. Let's clean it up.

Currently we have rdtscl, rdtscll, native_read_tsc, paravirt_read_tsc, and rdtsc_barrier. For people who haven't noticed rdtsc_barrier and who haven't carefully read the docs, there's no indication that all of the other accessors have a giant ordering gotcha. The macro forms are ugly, and the paravirt implementation is completely pointless.

rdtscl is particularly awful. It reads the low bits. There are no performance critical users of just the low bits anywhere in the kernel.

Clean it up. After this patch set, there are exactly three functions. rdtsc_unordered() is a function that does a raw RDTSC and returns a 64-bit number. rdtsc_ordered() is a function that does a properly ordered RDTSC for general-purpose use. barrier_before_rdtsc() is exactly what it sounds like.

Changes from v2:
- Rename rdtsc_unordered to just rdtsc
- Get rid of rdtsc_barrier entirely instead of renaming it
- The KVM patch is new (see above)
- Added some acks

Changes from v1:
- None, except that I screwed up the v1 emails.

Andy Lutomirski (18):
x86/tsc: Inline native_read_tsc and remove __native_read_tsc x86/msr/kvm: Remove vget_cycles()
x86/tsc/paravirt: Remove the read_tsc and read_tscp paravirt hooks x86/tsc: Replace rdtscll with native_read_tsc
x86/tsc: Remove the rdtscp and rdtscpll macros
x86/tsc: Use the full 64-bit tsc in tsc_delay x86/cpu/amd: Use the full 64-bit TSC to detect the 2.6.2 bug
baycom_epp: Replace rdtscl() with native_read_tsc() staging/lirc_serial: Remove TSC-based timing input/joystick/analog: Switch from rdtscl() to native_read_tsc() drivers/input/gameport: Replace rdtscl() with native_read_tsc() x86/tsc: Remove rdtscl()
x86/tsc: Rename native_read_tsc() to rdtsc()
x86: Add rdtsc_ordered() and use it in trivial call sites x86/tsc: Use rdtsc_ordered() in check_tsc_warp() and drop extra
barriers
x86/tsc: In read_tsc, use rdtsc_ordered() instead of get_cycles() x86/kvm/tsc: Drop extra barrier and use rdtsc_ordered in kvmclock x86/tsc: Remove rdtsc_barrier()

 arch/x86/boot/compressed/aslr.c                    |  2 +-
 arch/x86/entry/vdso/vclock_gettime.c               | 16 +-----
 arch/x86/include/asm/barrier.h                     | 11 ----
 arch/x86/include/asm/msr.h                         | 54 ++++++++++++-------
 arch/x86/include/asm/paravirt.h                    | 34 ------------
 arch/x86/include/asm/paravirt_types.h              |  2 -
 arch/x86/include/asm/pvclock.h                     | 21 ++++----
 arch/x86/include/asm/stackprotector.h              |  2 +-
 arch/x86/include/asm/tsc.h                         | 18 +------
 arch/x86/kernel/apb_timer.c                        |  8 +--
 arch/x86/kernel/apic/apic.c                        |  8 +--
 arch/x86/kernel/cpu/amd.c                          |  6 +--
 arch/x86/kernel/cpu/mcheck/mce.c                   |  4 +-
 arch/x86/kernel/espfix_64.c                        |  2 +-
 arch/x86/kernel/hpet.c                             |  4 +-
 arch/x86/kernel/paravirt.c                         |  2 -
 arch/x86/kernel/paravirt_patch_32.c                |  2 -
 arch/x86/kernel/trace_clock.c                      |  7 +--
 arch/x86/kernel/tsc.c                              | 12 ++---
 arch/x86/kernel/tsc_sync.c                         | 14 +++--
 arch/x86/kvm/lapic.c                               |  4 +-
 arch/x86/kvm/svm.c                                 |  4 +-
 arch/x86/kvm/vmx.c                                 |  4 +-
 arch/x86/kvm/x86.c                                 | 26 +++------
 arch/x86/lib/delay.c                               | 13 ++---
 arch/x86/um/asm/barrier.h                          | 13 -----
 arch/x86/xen/enlighten.c                           |  3 --
 drivers/input/gameport/gameport.c                  |  4 +-
 drivers/input/joystick/analog.c                    |  4 +-
 drivers/net/hamradio/baycom_epp.c                  |  2 +-
 drivers/staging/media/lirc/lirc_serial.c           | 63 ++--------------------
 drivers/thermal/intel_powerclamp.c                 |  4 +-
 .../power/cpupower/debug/kernel/cpufreq-test_tsc.c |  4 +-
 33 files changed, 110 insertions(+), 267 deletions(-)
Signature · 1 line
2.4.2