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    SubjectRe: [patch] releasing kernel lock during copy_from/to_user
    Andrea Arcangeli wrote:
    > If you'll measure something let me know the numbers. Also let me know if
    > 500 bytes is too low according to you.
    I've measured your original version.
    (I sent you that mail a few minutes ago)
    500 bytes sounds reasonable.

    I'll test (release if > x bytes) tonight//tomorrow.

    The main reason why I would prefer adding release_kernel_lock() outside
    uaccess.h is the stability:
    If we change uaccess.h, then this affects every obscure device driver,
    if we change filemap.c & tcp.c, then we achive 90 % if the speed gain
    with a far lower change to uncover some rare bugs.
    AND: since most obscure device drivers copy only a few bytes,
    the compare > 500 is wasted.

    OTHO, I wrote a patch which calls 'schedule_timeout()' during
    copy_??_user(), and the computer didn't crash immediately, but I
    got 1 deadlock after a few minutes.
    After I installed a deadlock-detection, the computer was stable...

    I'll install that patch again and perform a longer stress test.

    > >Could you please forward me the patch vs. 2.2.9?
    > Which one? buffer or unlocking?
    The unlocking patch. Comparing 2.2.9 & 2.2.9 with a small
    modification should provide more accurate benchmarks.


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