lkml.org 
[lkml]   [2011]   [Jul]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [PATCH] dio: Fast-path for page-aligned IOs
    From
    On Wed, Jul 27, 2011 at 2:08 PM, Christoph Hellwig <hch@infradead.org> wrote:
    > On Mon, Jun 20, 2011 at 04:17:35PM -0700, Dan Ehrenberg wrote:
    >> The fast path does not apply for operations of the wrong size
    >> or alignmnent, or for operations on raw drives with 512-byte sectors.
    >> It might be possible to make this special case a little more general
    >> while maintaining its performance benefits, but I do not believe that
    >> the full performance benefits can be achieved without resorting to
    >> special handling of simple cases, as is done in this patch.
    >
    > Did you check how this compares to Andis small optimizations?

    I'm having a little trouble getting his patch working. I hope to have
    this data soon, but I've been distracted by some other things.
    >
    > Also operations on raw disks are something people with fast devices
    > care about a lot.  We often hear about benchmark regressions due to
    > stupid little things in the direct I/O code.
    >
    > If we want to special case something that would be a very easy target,
    > with a 1:1 mapping of logical to physical blocks and thus no need
    > to call the allocator first, and no need for any kind of locking
    > or alignment handling.

    Are you talking about special-casing a raw block device? I'd like the
    optimization to also work with a file system to support a particular
    workload I've been looking at.

    Thanks,
    Dan
    --
    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: 2011-07-29 00:13    [W:0.026 / U:0.636 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site