lkml.org 
[lkml]   [2006]   [Jan]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [patch 00/21] mutex subsystem, -V14

    * Joel Schopp <jschopp@austin.ibm.com> wrote:

    > > Shouldn't you make that "isync" dependent on SMP too? UP doesn't
    > > need it, since DMA will never matter, and interrupts are precise.
    >
    > I think the isync is necessary to keep heavily out of order processors
    > from getting ahead of themselves even on UP. Scanning back through
    > the powerpc spinlock code they seem to take the same view there as
    > well.

    the asm/spinlock.h ops are only built on SMP kernels. mutex.h is for
    both UP and SMP. On UP you should need no synchronization, because the
    only way another context could interfere with your critical section is
    by getting interrupted, and interrupts are fully synchronizing, right?
    On UP the only synchronization needed is when a device reads/writes
    memory in parallel to the CPU.

    Ingo
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2006-01-06 00:45    [W:0.025 / U:31.284 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site