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    SubjectRe: [Bugme-new] [Bug 15618] New: 2.6.18->2.6.32->2.6.33 huge regression in performance
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    On Mar 23, 2010, at 6:45 PM, Linus Torvalds wrote:

    >
    >
    > On Tue, 23 Mar 2010, Ingo Molnar wrote:
    >>
    >> It shows a very brutal amount of page fault invoked mmap_sem spinning
    >> overhead.
    >
    > Isn't this already fixed? It's the same old "x86-64 rwsemaphores are using
    > the shit-for-brains generic version" thing, and it's fixed by
    >
    > 1838ef1 x86-64, rwsem: 64-bit xadd rwsem implementation
    > 5d0b723 x86: clean up rwsem type system
    > 59c33fa x86-32: clean up rwsem inline asm statements
    >
    > NOTE! None of those are in 2.6.33 - they were merged afterwards. But they
    > are in 2.6.34-rc1 (and obviously current -git). So Anton would have to
    > compile his own kernel to test his load.


    Applied mentioned patches. Things didn't improve too much.

    before:
    prog: Total exploration time 9.880 real 60.620 user 76.970 sys

    after:
    prog: Total exploration time 9.020 real 59.430 user 66.190 sys

    perf report:

    38.58% prog [kernel] [k] _spin_lock_irqsave
    37.42% prog ./prog [.] DBSLLlookup_ret
    6.22% prog ./prog [.] SuperFastHash
    3.65% prog /lib64/libc-2.11.1.so [.] __GI_memcpy
    2.09% prog ./anderson.6.dve2C [.] get_successors
    1.75% prog [kernel] [k] clear_page_c
    1.73% prog ./prog [.] index_next_dfs
    0.71% prog [kernel] [k] handle_mm_fault
    0.38% prog ./prog [.] cb_hook
    0.33% prog ./prog [.] get_local
    0.32% prog [kernel] [k] page_fault

    Anton.



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