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    SubjectRe: [kvm-devel] [PATCH/RFC 3/4]Introduce "account modifiers" mechanism
    Am Freitag, 17. August 2007 schrieb Laurent Vivier:
    > > The normal user/system accounting has the same issue, no? Whereever we
    > > happen to land (kernel or user) gets the whole tick.
    > Yes... but perhaps I should rewrite this too ;-)

    If you look further, you will see, that this was actually rewritten in 2.6.12
    and thats why we have cputime_t. The infrastructure is currently only used by
    s390 and ppc64. On s390 we use our cpu timer to get the current time on each
    syscall/irq/context switch etc to get precise accounting data for
    system/user/irq/softirq/nice. We also get steal time (this is interesting for
    the guest: how much of my cpu was actually not available because the
    hypervisor scheduled me away). I dont know enough about other architectures
    to say which one could exploit this infrastructure as well.

    The current git tree is somewhat broken for CONFIG_VIRT_CPU_ACCOUTING due to
    the accouting changes introduced by CFS - we work on this.

    If you are interested in the cputime stuff, you can have a look at
    arch/s390/kernel/vtime.c (account_system_vtime, account_vtime) as well as:;a=commit;h=6be7071fdd321c206b1ee7a3e534782f25572830
    for the first introduction and;a=commit;h=db59f519d37f80683f3611927f6b5c3bdfc0f9e6
    for the s390 exploitation.

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      Last update: 2007-08-17 15:35    [W:0.024 / U:36.824 seconds]
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