Hi, all
I was measuring some performance with help of xenoprofile 0.9.3 on Xen 3.3.0, and it worked well under direct mode (i.e., no shadow page table enabled)
But when I started Xen with parameter dom0_shadow=1, which enabled shadow page table, the benchmark performance downgraded greatly when xenoprofile was started. What's more, after I checked xm dmesg, I found pagetable walks were triggered several times due to reserved bit in page table:
(XEN) ----[ Xen-3.3.0 x86_64 debug=n Tainted: C ]----
(XEN) CPU: 4
(XEN) RIP: e008:[<ffff828c80152cb6>] __copy_from_user_ll+0x26/0x40
(XEN) RFLAGS: 0000000000010046 CONTEXT: hypervisor
==== BLAH BLAH BLAH ====
(XEN) Xen call trace:
(XEN) [<ffff828c80152cb6>] __copy_from_user_ll+0x26/0x40
(XEN) [<ffff828c801a5cba>] xenoprof_backtrace+0xfa/0x440
(XEN) [<ffff828c8011c105>] xenoprof_log_event+0xe5/0x1b0
(XEN) [<ffff828c801a584e>] ppro_check_ctrs+0x9e/0x120
(XEN) [<ffff828c801a47a9>] nmi_callback+0x29/0x80
(XEN) [<ffff828c8014e518>] do_nmi+0x38/0x100
(XEN) [<ffff828c801a6877>] handle_ist_exception+0x52/0x5b
(XEN)
(XEN) d0:v10: reserved bit in page table (ec=0009)
(XEN) Pagetable walk from 0000000000402540:
(XEN) L4[0x000] = 000000056265c067 5555555555555555
(XEN) L3[0x000] = 000000056212b067 5555555555555555
(XEN) L2[0x002] = 000000056215d067 5555555555555555
(XEN) L1[0x002] = ffffffffffffffff ffffffffffffffff
Has any one been confronted by this problem before?
Many thanks for your replies.
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