On Wed, Jul 27, 2011 at 2:08 PM, Christoph Hellwig <hch@xxxxxxxxxxxxx> 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-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
