On Sun, Oct 06 2002, Peter Osterlund wrote:
Hi!
I have updated the packet writing patch for use with kernel 2.5.40.
http://w1.894.telia.com/~u89404340/patches/packet/2.5/packet-2.5.40.patch.bz...
There are no exciting new features, only adaptions to kernel changes. Although this version works, I get the feeling that it is slower than it used to be. It looks like the packet driver isn't fed enough simultaneous requests. Are there any special tricks I should use to make the deadline I/O scheduler work well with a stacking block driver?
Maybe the loss of batching? That was recently adjusted down in the 2.5 kernels. The deadline scheduler itself should not give you any worse performance, in the general case. cd-rw has other costs that could be interesting to factor in. Things like switching from writing to reading, that comes with a cost as well. I _think_ the streamed i/o vs seeky i/o accounting should work fine for cds as well. If you can help me quantify what exactly is slower (or why it feels slower), then I can surely help you do a general solution for this. I would be inclined to say that you should just printk every request extracted from the io scheduler with the old version and with deadline and compare them. There just might be some obvious bug there. -- Jens Axboe