lkml.org 
[lkml]   [2010]   [Feb]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [PATCH 09/10] x86-32: use SSE for atomic64_read/set if available
    From
    > This is what kernel_fpu_begin/kernel_fpu_end is all about.  We
    > definitely cannot leave TS cleared without the user space CPU state
    > moved to its home location, or we have yet another complicated state to
    > worry about.

    It should be relatively simple to handle, since the current code
    doesn't really rely on the TS flag but uses TS_USEDFPU.
    It would mostly be a matter of making sure TS is restored on return to
    userspace if necessary.

    > I really feel that without a *strong* use case for this, there is
    > absolutely no point.
    For the specific 32-bit atomic64_t case, it is an improvement, but not
    necessarily significant in the big picture.
    Being able to efficiently use SSE in the kernel might however be more
    broadly useful.
    memcpy/memset/etc. (assuming SSE is the best option for these at least
    on some processors) and checksums come to mind.
    Also non-temporal SSE moves might be useful for things like memory
    compaction without clobbering caches.
    --
    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: 2010-02-18 19:17    [W:0.024 / U:0.604 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site