Messages in this thread |  | | From | kumon@flab ... | Date | Tue, 21 Nov 2000 20:30:33 +0900 | Subject | Re: [PATCH] livelock in elevator scheduling |
| |
Jens Axboe writes: > > Problem: > > Current elevator_linus() traverses the I/O requesting queue from the > > tail to top. And when the current request has smaller sector number > > than the request on the top of queue, it is always placed just after > > the top. > > This means, if requests in some sector range are continuously > > generated, a request with larger sector number is always places at the > > last and has no chance to go to the front. e.g. it is not scheduled. > > Believe it or not, but this is intentional. In that regard, the > function name is a misnomer -- call it i/o scheduler instead :-)
I never believe it intentional. If it is true, the current kernel will be suffered from a kind of DOS attack. Yes, actually I'm a victim of it.
By Running ZD's ServerBench, not only the performance down, but my machine blocks all commands execution including /bin/ps, /bin/ls... , and those are not ^C able unless the benchmark is stopped. Those commands are read from disks but the requests are wating at the end of I/O queue, those won't be executed.
Anyway, I'll try your patch.
-- Computer Systems Laboratory, Fujitsu Labs. kumon@flab.fujitsu.co.jp - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
|  |