changelog --------- v12 - v11 - splitted time: replace read_boot_clock64() with read_persistent_wall_and_boot_offset() into four patches - Added two patches one fixes an existing bug with text_poke() another one enables static branches early. Note, because I found and fixed the text_poke() bug, enabling static branching became super easy, as no changes to jump_label* is needed. - Modified x86/tsc: use tsc early to use static branches early, and thus native_sched_clock() is not changed at all. v11 - v10 - Addressed all the comments from Thomas Gleixner. - I added one more patch: "x86/tsc: prepare for early sched_clock" which fixes a problem that I discovered while testing. I am not particularly happy with the fix, as it adds a new argument that is used only in one place, but if you have a suggestion for a different approach on how to address this problem please let me know. v10 - v9 - Added another patch to this series that removes dependency between KVM clock, and memblock allocator. The benefit is that all clocks can now be initialized even earlier. v9 - v8 - Addressed more comments from Dou Liyang v8 - v7 - Addressed comments from Dou Liyang: - Moved tsc_early_init() and tsc_early_fini() to be all inside tsc.c, and changed them to be static. - Removed warning when notsc parameter is used. - Merged with: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git v7 - v6 - Removed tsc_disabled flag, now notsc is equivalent of tsc=unstable - Simplified changes to sched/clock.c, by removing the sched_clock_early() and friends as requested by Peter Zijlstra. We know always use sched_clock() - Modified x86 sched_clock() to return either early boot time or regular. - Added another example why ealry boot time is important v5 - v6 - Added a new patch: time: sync read_boot_clock64() with persistent clock Which fixes missing __init macro, and enabled time discrepancy fix that was noted by Thomas Gleixner - Split "x86/time: read_boot_clock64() implementation" into a separate patch v4 - v5 - Fix compiler warnings on systems with stable clocks. v3 - v4 - Fixed tsc_early_fini() call to be in the 2nd patch as reported by Dou Liyang - Improved comment before __use_sched_clock_early to explain why we need both booleans. - Simplified valid_clock logic in read_boot_clock64(). v2 - v3 - Addressed comment from Thomas Gleixner - Timestamps are available a little later in boot but still much earlier than in mainline. This significantly simplified this work. v1 - v2 In patch "x86/tsc: tsc early": - added tsc_adjusted_early() - fixed 32-bit compile error use do_div() The early boot time stamps were discussed recently in these threads: http://lkml.kernel.org/r/1527672059-6225-1-git-send-email-feng.tang@xxxxxxxxx http://lkml.kernel.org/r/1527672059-6225-2-git-send-email-feng.tang@xxxxxxxxx I updated my series to the latest mainline and sending it again. Peter mentioned he did not like patch 6,7, and we can discuss for a better way to do that, but I think patches 1-5 can be accepted separetly, since they already enable early timestamps on platforms where sched_clock() is available early. Such as KVM. Adding early boot time stamps support for x86 machines. SPARC patches for early boot time stamps are already integrated into mainline linux. Sample output ------------- Before: https://paste.ubuntu.com/26133428/ After: https://paste.ubuntu.com/26133523/ For exaples how early time stamps are used, see this work: Example 1: https://lwn.net/Articles/734374/ - Without early boot time stamps we would not know about the extra time that is spent zeroing struct pages early in boot even when deferred page initialization. Example 2: https://patchwork.kernel.org/patch/10021247/ - If early boot timestamps were available, the engineer who introduced this bug would have noticed the extra time that is spent early in boot. Pavel Tatashin (7): x86/tsc: remove tsc_disabled flag time: sync read_boot_clock64() with persistent clock x86/time: read_boot_clock64() implementation sched: early boot clock kvm/x86: remove kvm memblock dependency x86/paravirt: add active_sched_clock to pv_time_ops x86/tsc: use tsc early Example 3: http://lkml.kernel.org/r/20180615155733.1175-1-pasha.tatashin@xxxxxxxxxx - Needed early time stamps to show improvement Pavel Tatashin (11): x86: text_poke() may access uninitialized struct pages x86: initialize static branching early x86/tsc: redefine notsc to behave as tsc=unstable kvm/x86: remove kvm memblock dependency s390/time: add read_persistent_wall_and_boot_offset() time: replace read_boot_clock64() with read_persistent_wall_and_boot_offset() s390/time: remove read_boot_clock64() ARM/time: remove read_boot_clock64() x86/tsc: prepare for early sched_clock sched: early boot clock x86/tsc: use tsc early .../admin-guide/kernel-parameters.txt | 2 - Documentation/x86/x86_64/boot-options.txt | 4 +- arch/arm/kernel/time.c | 12 +--- arch/s390/kernel/time.c | 15 +++-- arch/x86/include/asm/text-patching.h | 1 + arch/x86/kernel/alternative.c | 10 ++- arch/x86/kernel/cpu/amd.c | 13 ++-- arch/x86/kernel/cpu/common.c | 38 ++++++----- arch/x86/kernel/kvm.c | 1 + arch/x86/kernel/kvmclock.c | 64 +++--------------- arch/x86/kernel/setup.c | 11 ++-- arch/x86/kernel/tsc.c | 65 ++++++++++--------- include/linux/timekeeping.h | 3 +- kernel/sched/clock.c | 10 ++- kernel/time/timekeeping.c | 61 ++++++++--------- 15 files changed, 140 insertions(+), 170 deletions(-) -- 2.17.1 -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
