Re: Disk priority dependend on nice level...

Pavel Machek
2003-08-06T23:42:30Z

Hi!

> I ported `subj` to 2.6.0-test2. I do not yet have idea if it works,
> but it compiles ;-).

It compiles, it event boots, but it does not seem to have much effect
:-(.

Test was like this:

bench:
#!/bin/bash
doit() {
echo Unloaded system:
time ./$1
echo No nice:
./$1 loadonly &
time ./$1
killall $1
killall bench_cat
echo Nice -19:
nice -n 19 ./$1 loadonly &
time ./$1
killall $1
killall bench_cat
}

doit diskload

diskload:
#!/bin/bash
if [ "a$1" == aloadonly ]; then
./bench_cat /usr/{bin,lib,lib/*}/* > /dev/null 2> /dev/null
exit
fi
umount /suse
mount /suse
./bench_cat /suse/usr/bin/* > /dev/null 2> /dev/null

bench_cat is copy of /bin/cat.
Pavel

>
> --- clean/drivers/block/deadline-iosched.c 2003-07-27 22:31:10.000000000 +0200
> +++ linux/drivers/block/deadline-iosched.c 2003-08-07 01:26:47.000000000 +0200
> @@ -17,6 +17,7 @@
> #include <linux/compiler.h>
> #include <linux/hash.h>
> #include <linux/rbtree.h>
> +#include <linux/sched.h>
>
> /*
> * See Documentation/deadline-iosched.txt
> @@ -106,6 +107,19 @@
> #define RQ_DATA(rq) ((struct deadline_rq *) (rq)->elevator_private)
>
> /*
> + * scale_deadline
> + */
> +static int scale_deadline(int default_deadline)
> +{
> + int prio = current->static_prio - MAX_RT_PRIO;
> + /* make priorities higher than nice -10 equal to nice -10 */
> + if (prio < 10)
> + prio = 10;
> + /* scale the deadline according to priority */
> + return default_deadline * prio/20;
> +}
> +
> +/*
> * the back merge hash support functions
> */
> static inline void __deadline_del_drq_hash(struct deadline_rq *drq)
> @@ -303,7 +317,7 @@
> /*
> * set expire time (only used for reads) and add to fifo list
> */
> - drq->expires = jiffies + dd->fifo_expire[data_dir];
> + drq->expires = jiffies + scale_deadline(dd->fifo_expire[data_dir]);
> list_add_tail(&drq->fifo, &dd->fifo_list[data_dir]);
> }
>
>

--
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]