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When we create or move a memory slot, we need to zap mmio sptes. Currently, zap_all() is used for this and this is causing two problems: - extra page faults after zapping mmu pages - long mmu_lock hold time during zapping mmu pages For the latter, Marcelo reported a disastrous mmu_lock hold time during hot-plug, which made the guest unresponsive for a long time. This patch takes a simple way to fix these problems: do not zap mmu pages unless they are marked mmio cached. On our test box, this took only 50us for the 4GB guest and we did not see ms of mmu_lock hold time any more. Note that we still need to do zap_all() for other cases. So another work is also needed: Xiao's work may be the one. Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp> Signed-off-by: Gleb Natapov <gleb@redhat.com> |
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| boot | ||
| configs | ||
| crypto | ||
| ia32 | ||
| include | ||
| kernel | ||
| kvm | ||
| lguest | ||
| lib | ||
| math-emu | ||
| mm | ||
| net | ||
| oprofile | ||
| pci | ||
| platform | ||
| power | ||
| realmode | ||
| syscalls | ||
| tools | ||
| um | ||
| vdso | ||
| video | ||
| xen | ||
| .gitignore | ||
| Kbuild | ||
| Kconfig | ||
| Kconfig.cpu | ||
| Kconfig.debug | ||
| Makefile | ||
| Makefile_32.cpu | ||
| Makefile.um | ||