Arch Linux

hydra35

Member

Registered: 2012-06-29

Posts: 1

Random read write performance drop in Linux kernel 3.x

Hi:

I did some benchmark on RHEL 6.2 with kernel 2.6.32 and ArchLinux with kernel 3.4. The testing focus on raw disk performance, so there is no filesystem involved.

The results show almost 10% performance drop in random read and random write. The hardware used for test is two 7200RPM SATA under Raid0

Below is the fio benchmark result:

                                seq-read        seq-write       rand-read     rand-write
                                8k     256k     8k     256k     8k   256k     8k   256k
------------------------------------------------------------------------------------------------------------------------
RHEL 6.2(2.6.32)       220377 265200   13867  260720   1692 23317    1507  23243
ArchLinux(3.4)           211946 266377   14079  260107   1541 21133    1383  21177

ArchLinux V.S. RHEL：
                    8k     256k 
---------------------------------------------
seq-read            -4%     +0.3%
seq-write           +1.5%  -0.2%
rand-read           -8.9%   -2.4%
rand-write          -8%      -8.8%

Although the test case didn't have a good coverage(i.e. only test 8K / 256K), the result can be reproduced consistently.

Sample FIO configuration:

[global]
bs=256K
direct=1
rw=write
ioengine=libaio
iodepth=8
runtime=20
[/dev/sda4]