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Commit 0cbf8e43 authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Gleb Natapov
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KVM: MMU: document write_flooding_count 



Document write_flooding_count to Documentation/virtual/kvm/mmu.txt

Signed-off-by: default avatarXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent accaefe0

Documentation/virtual/kvm/mmu.txt

+9 −0
Original line number Diff line number Diff line
@@ -215,6 +215,15 @@ Shadow pages contain the following information: 
    atomically.  The reader uses this while running out of the MMU lock

    to detect in-progress updates and retry them until the writer has

    finished the write.

  write_flooding_count:

    A guest may write to a page table many times, causing a lot of

    emulations if the page needs to be write-protected (see "Synchronized

    and unsynchronized pages" below).  Leaf pages can be unsynchronized

    so that they do not trigger frequent emulation, but this is not

    possible for non-leafs.  This field counts the number of emulations

    since the last time the page table was actually used; if emulation

    is triggered too frequently on this page, KVM will unmap the page

    to avoid emulation in the future.



Reverse map

===========

arch/x86/include/asm/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -233,6 +233,7 @@ struct kvm_mmu_page { 
	int clear_spte_count;

#endif



	/* Number of writes since the last time traversal visited this page.  */

	int write_flooding_count;

};