qemu-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Qemu-devel] QEMU throughput is down with SMP


From: Venkateswararao Jujjuri (JV)
Subject: [Qemu-devel] QEMU throughput is down with SMP
Date: Wed, 29 Sep 2010 17:50:15 -0700
User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.9) Gecko/20100915 Thunderbird/3.1.4

Code: Mainline QEMU (git://git.qemu.org/qemu.git)
Machine: LS21 blade.
Disk: Local disk through VirtIO.
Did not select any cache option. Defaulting to writethrough.

Command tested:
3 parallel instances of : dd if=/dev/zero of=/pmnt/my_pw bs=4k count=100000

QEMU with  smp=1
19.3 MB/s + 19.2 MB/s + 18.6 MB/s = 57.1 MB/s

QEMU with smp=4
15.3 MB/s + 14.1 MB/s + 13.6 MB/s = 43.0 MB/s

Is this expected?


Thanks,
JV

=== Details ===
smp = 1

time dd if=/dev/zero of=/pmnt/my_pw bs=4k count=100000 & time dd if=/dev/zero of=/pmnt/my_pw1 bs=4k count=100000 & time dd if=/dev/zero of=/pmnt/my_pw2 bs=4k count=100000 &


address@hidden ~]# 100000+0 records in
100000+0 records out
409600000 bytes (410 MB) copied, 21.2747 s, 19.3 MB/s

real    0m21.377s
user    0m0.040s
sys     0m1.655s
100000+0 records in
100000+0 records out
409600000 bytes (410 MB) copied, 21.2799 s, 19.2 MB/s

real    0m21.374s
user    0m0.046s
sys     0m1.660s
100000+0 records in
100000+0 records out
409600000 bytes (410 MB) copied, 22.0735 s, 18.6 MB/s

real    0m22.153s
user    0m0.043s
sys     0m1.642s


smp = 4
address@hidden ~]# time dd if=/dev/zero of=/pmnt/my_pw bs=4k count=100000 & time dd if=/dev/zero of=/pmnt/my_pw1 bs=4k count=100000 & time dd if=/dev/zero of=/pmnt/my_pw2 bs=4k count=100000 &
address@hidden ~]# 100000+0 records in
100000+0 records out
409600000 bytes (410 MB) copied, 26.8055 s, 15.3 MB/s

real    0m26.869s
user    0m0.079s
sys     0m3.333s
100000+0 records in
100000+0 records out
409600000 bytes (410 MB) copied, 28.9583 s, 14.1 MB/s

real    0m29.018s
user    0m0.053s
sys     0m4.313s
100000+0 records in
100000+0 records out
409600000 bytes (410 MB) copied, 30.1739 s, 13.6 MB/s

real    0m30.238s
user    0m0.065s
sys     0m4.124s




reply via email to

[Prev in Thread] Current Thread [Next in Thread]