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    SubjectRe: [rfc 19/45] cpu alloc: NFS statistics
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    On Tue, 2007-11-20 at 16:28 -0500, Mathieu Desnoyers wrote:
    > * Trond Myklebust (trond.myklebust@fys.uio.no) wrote:
    > >
    > > On Tue, 2007-11-20 at 12:49 -0800, Christoph Lameter wrote:
    > > > On Tue, 20 Nov 2007, Mathieu Desnoyers wrote:
    > > >
    > > > > > Index: linux-2.6/fs/nfs/iostat.h
    > > > > > ===================================================================
    > > > > > --- linux-2.6.orig/fs/nfs/iostat.h 2007-11-15 21:17:24.391404458 -0800
    > > > > > +++ linux-2.6/fs/nfs/iostat.h 2007-11-15 21:25:33.167654066 -0800
    > > > > > @@ -123,7 +123,7 @@ static inline void nfs_inc_server_stats(
    > > > > > int cpu;
    > > > > >
    > > > > > cpu = get_cpu();
    > > > > > - iostats = per_cpu_ptr(server->io_stats, cpu);
    > > > > > + iostats = CPU_PTR(server->io_stats, cpu);
    > > > > > iostats->events[stat] ++;
    > > > >
    > > > > Is there a way to change this into a CPU_ADD ?
    > > >
    > > > Yes I must have missed that.
    > > >
    > > > Could be
    > > >
    > > > CPU_INC(server->io_stats->events[stat]);
    > > >
    > > > >
    > > > > > put_cpu_no_resched();
    > > > >
    > > > > Why put_cpu_no_resched here ?
    > > >
    > > > We do not want to reschedule here? We may have already disabled interrupts
    > > > or some such thing.
    > >
    > > Some of these statistics are updated from inside a spinlocked
    > > environment, hence the put_no_resched().
    > >
    >
    > The we could use __get_cpu_var instead ? (since we know preemption is
    > _always_ disabled when we are called) ?

    We don't know that. I said that _some_ of these statistics are updated
    in that way.

    Cheers
    Trond

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