| Message ID | 20200531182453.15254-1-ggherdovich@suse.cz |
|---|---|
| Headers | show |
| Series | More frequency invariance fixes for x86 | expand |
On Mon, Jun 01, 2020 at 04:34:18PM -0700, Ricardo Neri wrote: > On Sun, May 31, 2020 at 08:24:52PM +0200, Giovanni Gherdovich wrote: > > There may be CPUs that support turbo boost but don't declare any turbo > > ratio, i.e. their MSR_TURBO_RATIO_LIMIT is all zeroes. In that condition > > scale-invariant calculations can't be performed. > > > > Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.cz> > > Suggested-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com> > > FWIW, > > Tested-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com> Is this going to make it as a fix to 5.8? Tested-by: Ira Weiny <ira.weiny@intel.com>
v1 at https://lore.kernel.org/lkml/20200428132450.24901-1-ggherdovich@suse.cz/ changes wrt v1: - add Peter Zijlstra's code to check for multiplication overflow, see https://lore.kernel.org/lkml/20200501133042.GE3762@hirez.programming.kicks-ass.net/ - put all frequence invariant code behind CONFIG_X86_64, as the overflow checks need 64 bits operations, see the build error at https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org/thread/7GDIBOMNVDG5W2XZD4EICE2TUZR3THBN/ - add additional patch to check for when base_freq > turbo_freq, suggested by Peter Zijlstra at https://lore.kernel.org/lkml/20200501130427.GD3762@hirez.programming.kicks-ass.net/ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Cover Letter from v1: Patch 1/2 prevents a division by zero in case the product "delta_MPERF * arch_max_freq_ratio" overflows u64, as suggested by Linus at [1]. This patch supersedes the version at [2], as it also disables frequency invariance when that overflow happens. Patch 2/2 implements the recommendation by Ricardo Neri to check for an all zero MSR_TURBO_RATIO_LIMIT and disable freq invariance in that case too. [1] https://lore.kernel.org/lkml/CAHk-=wiX+NT2yxtdPszH9U_S96MCNQA56GJFXY45mZc47yG5KQ@mail.gmail.com/ [2] https://lore.kernel.org/lkml/20200422144055.18171-1-ggherdovich@suse.cz/ [3] https://lore.kernel.org/lkml/20200424013222.GA26355@ranerica-svr.sc.intel.com/ Giovanni Gherdovich (3): x86, sched: check for counters overflow in frequency invariant accounting x86, sched: Bail out of frequency invariance if turbo frequency is unknown x86, sched: Bail out of frequency invariance if turbo_freq/base_freq gives 0 arch/x86/include/asm/topology.h | 2 +- arch/x86/kernel/smpboot.c | 50 +++++++++++++++++++++++++++++++++-------- 2 files changed, 42 insertions(+), 10 deletions(-)