手册ionice
页说
仅当在定义的宽限期内没有其他程序请求磁盘 io 时,以空闲 io 优先级运行的程序才会获得磁盘时间。
这个“宽限期”在哪里定义?它是否可见/可调(可能通过 /sys)?
答案1
宽限期为 250 毫秒。
http://lkml.indiana.edu/hypermail/linux/kernel/0412.2/1099.html
There is an idle scheduling class, which only runs when nothing else
is using the disk. A grace period is defined for which idle has to
wait before getting disk access when other io has run. This defaults
to 250ms currently.
您没有提供操作系统版本或发行版(是的,这确实有区别),但 RHEL/CentOS 5+6 的可调参数是定义在这里作为fifo_expire_async(其中/sys/block/[device]/queue/iosched/
[device] 是 sda、sdb、cciss0 等)。