For the third part, the throughput is about as high as your disk is capable of given the spread of files. The reason it's not max'd out is that we have to seek over bits of the disk we don't want/need in the page cache. We use the I/O elevator as efficiently as we can to merge reads, but at the end of the day, we have to seek.
Even more interesting is that the obvious "dips" correspond to the on-disk positions of your inode tables and suchlike ;) they take quite a jump to get over
For the third part, the throughput is about as high as your disk is capable of given the spread of files. The reason it's not max'd out is that we have to seek over bits of the disk we don't want/need in the page cache. We use the I/O elevator as efficiently as we can to merge reads, but at the end of the day, we have to seek.
Even more interesting is that the obvious "dips" correspond to the on-disk positions of your inode tables and suchlike ;) they take quite a jump to get over