On 24.03.2011 02:38, Miao Xie wrote: > On wed, 23 Mar 2011 21:28:25 +0100, Arne Jansen wrote: >> On 23.03.2011 20:26, Andrey Kuzmin wrote: >>> On Wed, Mar 23, 2011 at 4:06 PM, Arne Jansen<sensi...@gmx.net> wrote: >>>> The main idea is to load the tree (or parts of it) top-down, order the >>>> needed blocks and distribute it over all disks. >>>> To keep you interested, some results first. >>>> >>>> a) by tree enumeration with reada=2 >>>> reading extent tree: 242s >>>> reading csum tree: 140s >>>> reading both trees: 324s >>>> >>>> b) prefetch prototype >>>> reading extent tree: 23.5s >>>> reading csum tree: 20.4s >>>> reading both trees: 25.7s >>> >>> 10x speed-up looks indeed impressive. Just for me to be sure, did I >>> get you right in that you attribute this effect specifically to >>> enumerating tree leaves in key address vs. disk addresses when these >>> two are not aligned? >> >> Yes. Leaves and the intermediate nodes tend to be quite scattered >> around the disk with respect to their logical order. >> Reading them in logical (ascending/descending) order require lots >> of seeks. > > I'm also dealing with tree fragmentation problem, I try to store the leaves > which have the same parent closely.
That's good to hear. Do you have already anything I can repeat the test with? -Arne > > Regards > Miao > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
