hyperv/storvsc: tune storage performance by changing io max and channel selection
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Authored by honzhan_microsoft.com on Aug 24 2016, 6:43 AM.

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howard0su_gmail.com
decui_microsoft.com
hrs
delphij
sepherosa_gmail.com
royger

Commits

rS304791: hyperv/storvsc: Increase queue depth and rework channel selection.

Summary

Storage performance IOPS or latency will degrade under multiple thread test with FIO, when comparing with Linux for Hyper-V. The possible reasons are:
(1) IO request queue is not as long as Linux.
(2) outgoing channels were not fully utilized.

So, this fix targets to improve the storage performance by 2.2X on Azure with RAID0 (12 SSD 1T disks) after enlarging the max io request queue, and considering both CPUID and LUN for channel selection.

Submitted by: Hongjiang Zhang <honzhan microsoft com>

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honzhan_microsoft.com updated this revision to Diff 19615.Aug 24 2016, 6:43 AM

honzhan_microsoft.com retitled this revision from to hyperv/storvsc: tune storage performance by changing io max and channel selection.

Herald added subscribers: Contributor Reviews (src), imp. · View Herald TranscriptAug 24 2016, 6:43 AM

honzhan_microsoft.com updated this object.Aug 24 2016, 6:51 AM

honzhan_microsoft.com added reviewers: hrs, decui_microsoft.com, sepherosa_gmail.com, howard0su_gmail.com, royger, delphij.

sepherosa_gmail.com added inline comments.Aug 24 2016, 6:59 AM

sys/dev/hyperv/storvsc/hv_storvsc_drv_freebsd.c
139	Since the variable is u_int, we should use SYSCTL_UINT here.
723	We probably should combine this two lines. Since ch_sel is only used once here.
sys/dev/hyperv/vmbus/vmbus_chan.c
1333 ↗	(On Diff #19615)	I don't think we need this. vmbus_subchan_get() is already there.
sys/dev/hyperv/vmbus/vmbus_chanvar.h
92	This does not look correct :P
136	Probably put it in drivers instead of in channel. Not all drivers need this stat.