IO Sheduler
From Alessandro's Wiki
- changing I/O scheduler at runtime, in this case, we switch to deadline:
cd /sys/block/sda/queue echo deadline > scheduler
- benchmark of disk read speed, changing IO scheduler in the kernel.
Block layer->IO Schedulers->Default I/O scheduler->Anticipatory (DEFAULT_AS) Processor type and features->Processor family->Preemption Model->Preemptible Kernel (Low-Latency Desktop) (PREEMPT)
hdparm -tT /dev/hd[abcd]
/dev/hda:
Timing cached reads: 3036 MB in 2.00 seconds = 1516.74 MB/sec Timing buffered disk reads: 140 MB in 3.03 seconds = 46.16 MB/sec
/dev/hdb:
Timing cached reads: 3128 MB in 2.00 seconds = 1563.28 MB/sec Timing buffered disk reads: 156 MB in 3.03 seconds = 51.41 MB/sec
/dev/hdc:
Timing cached reads: 3228 MB in 2.00 seconds = 1611.95 MB/sec Timing buffered disk reads: 136 MB in 4.02 seconds = 33.81 MB/sec
/dev/hdd:
Timing cached reads: 3144 MB in 2.00 seconds = 1570.76 MB/sec Timing buffered disk reads: 192 MB in 3.01 seconds = 63.77 MB/sec
- TEST2
Block layer->IO Schedulers->Default I/O scheduler->Deadline (DEFAULT_DEADLINE) Processor type and features->Processor family->Preemption Model->Voluntary Kernel Preemption (Desktop) (PREEMPT_VOLUNTARY)
/dev/hda: Timing cached reads: 3528 MB in 2.00 seconds = 1762.73 MB/sec Timing buffered disk reads: 154 MB in 3.03 seconds = 50.77 MB/sec
/dev/hdb: Timing cached reads: 3868 MB in 2.00 seconds = 1933.38 MB/sec Timing buffered disk reads: 172 MB in 3.03 seconds = 56.82 MB/sec
/dev/hdc:
Timing cached reads: 3692 MB in 2.00 seconds = 1846.51 MB/sec Timing buffered disk reads: 164 MB in 3.02 seconds = 54.33 MB/sec
/dev/hdd:
Timing cached reads: 3800 MB in 2.00 seconds = 1899.48 MB/sec Timing buffered disk reads: 196 MB in 3.01 seconds = 65.18 MB/sec
- TEST3
Block layer->IO Schedulers->Default I/O scheduler->CFQ Processor type and features->Processor family->Preemption Model->Voluntary Kernel Preemption (Desktop) (PREEMPT_VOLUNTARY)
/dev/hda: Timing cached reads: 3240 MB in 2.00 seconds = 1618.93 MB/sec Timing buffered disk reads: 136 MB in 3.01 seconds = 45.14 MB/sec
/dev/hdb: Timing cached reads: 3644 MB in 2.00 seconds = 1821.72 MB/sec Timing buffered disk reads: 170 MB in 3.00 seconds = 56.59 MB/sec
/dev/hdc: Timing cached reads: 3772 MB in 2.00 seconds = 1885.97 MB/sec Timing buffered disk reads: 164 MB in 3.03 seconds = 54.21 MB/sec
/dev/hdd: Timing cached reads: 3616 MB in 2.00 seconds = 1806.91 MB/sec Timing buffered disk reads: 198 MB in 3.01 seconds = 65.80 MB/sec