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[Xen-users] xen4 on debian squeeze, slow mysql in domU

To: <xen-users@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-users] xen4 on debian squeeze, slow mysql in domU
From: <s3t@xxxxxxxxxx>
Date: Sat, 23 Oct 2010 15:11:52 +0200
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hi,
i have a mysql server in guest domU on debian squeeze.
when i create test table and do INSERT INTO test (name, value) VALUES(RAND(), RAND());
Query OK, 1 row affected (0.28 sec)

at other physical server with same configuration
Query OK, 1 row affected (0.00 sec)

i try this several time but on physical server max value never get over 0.05sec and on VM lowest value was 0.13sec.
another tests:
sysbench --num-threads=16 --max-requests=1000 --test=oltp --oltp-table-size=1000 --mysql-socket=/var/run/mysqld/mysqld.sock --mysql-user=root run

on physical server:
----------------------------------------------------------------
OLTP test statistics:
queries performed:
read: 15568
write: 5228
other: 2112
total: 22908
transactions: 1000 (436.65 per sec.)
deadlocks: 112 (48.91 per sec.)
read/write requests: 20796 (9080.65 per sec.)
other operations: 2112 (922.21 per sec.)

Test execution summary:
total time: 2.2901s
total number of events: 1000
total time taken by event execution: 35.0599
per-request statistics:
min: 2.51ms
avg: 35.06ms
max: 365.01ms
approx. 95 percentile: 73.80ms

Threads fairness:
events (avg/stddev): 62.5000/9.62
execution time (avg/stddev): 2.1912/0.14
----------------------------------------------------------------


on VM:
----------------------------------------------------------------
OLTP test statistics:
queries performed:
read: 14280
write: 5048
other: 2020
total: 21348
transactions: 1000 (177.26 per sec.)
deadlocks: 20 (3.55 per sec.)
read/write requests: 19328 (3426.02 per sec.)
other operations: 2020 (358.06 per sec.)

Test execution summary:
total time: 5.6415s
total number of events: 1000
total time taken by event execution: 89.6339
per-request statistics:
min: 35.81ms
avg: 89.63ms
max: 275.89ms
approx. 95 percentile: 115.18ms

Threads fairness:
events (avg/stddev): 62.5000/1.58
execution time (avg/stddev): 5.6021/0.03
----------------------------------------------------------------

can someone share his experience with using mysql server in xen domU?
what can be wrong?


dom0: Xeon E5520 2.27GHz, 8GB ram, debian squeeze, xen-hypervisor-4.0-amd64 Version: 4.0.1-1
domU: vcpus = '8',memory = '4096', debian squeeze
physical server: core2quad Q9300 2.50GHz, 4GB, debian lenny
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