[PATCH 0/3] deadline-iosched: performance, style and documentation changes

Aaron Carroll
2008-08-14T09:04:06Z

Hi Jens,

Patch 1 changes deadline to dispatch in a CSCAN-like manner for improved
throughput. This fixes two performance issues, namely deadline avalanche
that occurs under high load, and FCFS-like behaviour for mixed read/write
workloads. Benchmark results are below.

Patches 2 and 3 introduce some non-functional changes, mostly for style
and documentation.

Thanks,
-- Aaron

-----------------------------------x8-----------------------------------

Figures quoted in KiB/s unless otherwise noted. Disk under test is a 73GiB
15krpm Cheetah. Host machine is a 2-way IA64 w/ 2GiB RAM.

fio 16KiB reads
-------------------------------

Load Bandwidth %
New Old
32 3585.789 3580.412 0.1
64 3657.062 3361.460 8.8
128 3844.572 2459.811 56
256 3860.864 2455.446 57
512 3896.296 2472.468 58

fio 16KiB read/write (50/50)
-------------------------------

Load Bandwidth %
New Old
32 3461.336 2630.765 32
64 3715.625 2369.822 57
128 3931.525 2375.380 66
256 3953.333 2377.132 66

fio 1MiB reads
-------------------------------

Load Bandwidth %
New Old
32 49502.789 45744.023 8.2
64 50109.827 45776.416 9.5
128 50232.672 45884.900 9.5
256 50641.255 46266.082 9.5

fio 1MiB read/write (50/50)
-------------------------------

Load Bandwidth %
New Old
32 48543.272 44557.494 8.9
64 49388.251 44597.785 11
128 49794.080 45131.637 10
256 50632.356 45777.333 11

Postmark
-------------------------------

5 instances, 10k files, 100 dirs, 15k xacts, XFS

Old: 10.79 xact/s
New: 11.26 xact/s (+4.2%)