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hyperv/storvsc: tune storage performance by changing io max and channel selection

Authored by on Aug 24 2016, 6:43 AM.
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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>

Diff Detail

rS FreeBSD src repository - subversion
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Event Timeline retitled this revision from to hyperv/storvsc: tune storage performance by changing io max and channel selection.
133 ↗(On Diff #19615)

Since the variable is u_int, we should use SYSCTL_UINT here.

718 ↗(On Diff #19615)

We probably should combine this two lines. Since ch_sel is only used once here.

1333 ↗(On Diff #19615)

I don't think we need this. vmbus_subchan_get() is already there.

92 ↗(On Diff #19615)

This does not look correct :P

136 ↗(On Diff #19615)

Probably put it in drivers instead of in channel. Not all drivers need this stat.

This revision was automatically updated to reflect the committed changes.