Dave Howorth wrote:
Linda Walsh wrote:
No such thing in standard linux. The cpu nice doesn't affect the disk-io priority unless you have the non-standard "cfq" scheduling algorithm enabled. The default when I installed 10.2 recently, I believe was the 'anticipatory' deadline. Unfortunately, while it may be good for server workloads, and better for throughput, 'cfq' is better for interactive use. A background process can easily saturate the disk if it runs at full speed (even if process is 'niced' down).
I'm curious and didn't find an answer with a quick google. How does one inspect what algorithm is in use and/or change it? Is it a runtime option or build-time?
It has to be built in when the kernel is built, but I think both 10.2 and 10.3 have the alternate I/O schedulers compiled in as modules. The default can be set at compile time. So far, I only know of a way to change schedulers at boot time. Booting the kernel with the "elevator=" argument allows specifying an I/O scheduler. Valid values (if they are all compiled in) are: elevator=as elevator=cfq elevator=deadline elevator=noop They choose/enable the "Anticipatory", "completely fair queuing", "deadline", or "noop" schedulers, respectively. I believe the default used to be "anticipatory", but this isn't ideal for desktop use, but tries to optimize total throughput (good for servers processing large non-interactive programs). The "ionice" command in util-linux allows modifying cfq priorities. Recommended google search terms (from book "Linux Kernel Primer") would be "Modular IO Schedulers" and "Jens Axboe". In my quick search just now, didn't see anything about run-time selection, but didn't go far down the page. The boot time option might be the only way to go right now... Sorry couldn't be more help.... linda -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org