Re: [PATCH v9 00/19] qspinlock: a 4-byte queue spinlock with PV support

From: Waiman Long
Date: Wed May 07 2014 - 11:00:39 EST


On 04/27/2014 02:09 PM, Raghavendra K T wrote:

For kvm part feel free to add:
Tested-by: Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx>

V9 testing has shown no hangs.
I was able to do some performance testing. here are the results:

Overall we are seeing good improvement for pv-unfair version.

System : 32 cpu sandybridge with HT on. (4 node machine with 32 GB each)
Guest: 8GB with 16 vcpu/VM.
Average was taken over 8-10 data points.

Base = 3.15-rc2 with PRAVIRT_SPINLOCK = y
A = 3.15-rc2 + qspinlock v9 patch with QUEUE_SPINLOCK = y PRAVIRT_SPINLOCK = y PARAVIRT_UNFAIR_LOCKS = y (unfair lock)
B = 3.15-rc2 + qspinlock v9 patch with QUEUE_SPINLOCK = y PRAVIRT_SPINLOCK = n PARAVIRT_UNFAIR_LOCKS = n (queue spinlock without paravirt)
C = 3.15-rc2 + qspinlock v9 patch with QUEUE_SPINLOCK = y PRAVIRT_SPINLOCK = y PARAVIRT_UNFAIR_LOCKS = n (queue spinlock with paravirt)


Ebizzy % improvements
========================
overcommit A B C
0.5x 4.4265 2.0611 1.5824
1.0x 0.9015 -7.7828 4.5443
1.5x 46.1162 -2.9845 -3.5046
2.0x 99.8150 -2.7116 4.7461

Dbench %improvements
overcommit A B C
0.5x 3.2617 3.5436 2.5676
1.0x 0.6302 2.2342 5.2201
1.5x 5.0027 4.8275 3.8375
2.0x 23.8242 4.5782 12.6067

Absolute values of base results: (overcommit, value, stdev)
Ebizzy ( records / sec with 120 sec run)
0.5x 20941.8750 (2%)
1.0x 17623.8750 (5%)
1.5x 5874.7778 (15%)
2.0x 3581.8750 (7%)

Dbench (throughput in MB/sec)
0.5x 10009.6610 (5%)
1.0x 6583.0538 (1%)
1.5x 3991.9622 (4%)
2.0x 2527.0613 (2.5%)


Thank for the testing. I will include your Test-by tag in the next version.

-Longman
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