Hi, It is been two weeks, and no review activity yet. Please help with reviewing this work. Thank you, Pasha On Thu, Aug 8, 2019 at 2:44 PM Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> wrote: > > Just a friendly reminder, please send your comments on this series. > It's been a week since I sent out these patches, and no feedback yet. > Also, I'd appreciate if anyone could test this series on vhe hardware > with vhe kernel, it does not look like QEMU can emulate it yet > > Thank you, > Pasha > > On Thu, Aug 1, 2019 at 11:24 AM Pavel Tatashin > <pasha.tatashin@xxxxxxxxxx> wrote: > > > > Enable MMU during kexec relocation in order to improve reboot performance. > > > > If kexec functionality is used for a fast system update, with a minimal > > downtime, the relocation of kernel + initramfs takes a significant portion > > of reboot. > > > > The reason for slow relocation is because it is done without MMU, and thus > > not benefiting from D-Cache. > > > > Performance data > > ---------------- > > For this experiment, the size of kernel plus initramfs is small, only 25M. > > If initramfs was larger, than the improvements would be greater, as time > > spent in relocation is proportional to the size of relocation. > > > > Previously: > > kernel shutdown 0.022131328s > > relocation 0.440510736s > > kernel startup 0.294706768s > > > > Relocation was taking: 58.2% of reboot time > > > > Now: > > kernel shutdown 0.032066576s > > relocation 0.022158152s > > kernel startup 0.296055880s > > > > Now: Relocation takes 6.3% of reboot time > > > > Total reboot is x2.16 times faster. > > > > Previous approaches and discussions > > ----------------------------------- > > https://lore.kernel.org/lkml/20190709182014.16052-1-pasha.tatashin@xxxxxxxxxx > > reserve space for kexec to avoid relocation, involves changes to generic code > > to optimize a problem that exists on arm64 only: > > > > https://lore.kernel.org/lkml/20190716165641.6990-1-pasha.tatashin@xxxxxxxxxx > > The first attempt to enable MMU, some bugs that prevented performance > > improvement. The page tables unnecessary configured idmap for the whole > > physical space. > > > > https://lore.kernel.org/lkml/20190731153857.4045-1-pasha.tatashin@xxxxxxxxxx > > No linear copy, bug with EL2 reboots. > > > > Pavel Tatashin (8): > > kexec: quiet down kexec reboot > > arm64, mm: transitional tables > > arm64: hibernate: switch to transtional page tables. > > kexec: add machine_kexec_post_load() > > arm64, kexec: move relocation function setup and clean up > > arm64, kexec: add expandable argument to relocation function > > arm64, kexec: configure transitional page table for kexec > > arm64, kexec: enable MMU during kexec relocation > > > > arch/arm64/Kconfig | 4 + > > arch/arm64/include/asm/kexec.h | 51 ++++- > > arch/arm64/include/asm/pgtable-hwdef.h | 1 + > > arch/arm64/include/asm/trans_table.h | 68 ++++++ > > arch/arm64/kernel/asm-offsets.c | 14 ++ > > arch/arm64/kernel/cpu-reset.S | 4 +- > > arch/arm64/kernel/cpu-reset.h | 8 +- > > arch/arm64/kernel/hibernate.c | 261 ++++++----------------- > > arch/arm64/kernel/machine_kexec.c | 199 ++++++++++++++---- > > arch/arm64/kernel/relocate_kernel.S | 196 +++++++++--------- > > arch/arm64/mm/Makefile | 1 + > > arch/arm64/mm/trans_table.c | 273 +++++++++++++++++++++++++ > > kernel/kexec.c | 4 + > > kernel/kexec_core.c | 8 +- > > kernel/kexec_file.c | 4 + > > kernel/kexec_internal.h | 2 + > > 16 files changed, 758 insertions(+), 340 deletions(-) > > create mode 100644 arch/arm64/include/asm/trans_table.h > > create mode 100644 arch/arm64/mm/trans_table.c > > > > -- > > 2.22.0 > >
