RFT: virtio_net: limit xmit polling

RFT: virtio_net: limit xmit polling

[Michael S. Tsirkin]

OK, different people seem to test different trees.  In the hope to get
everyone on the same page, I created several variants of this patch so
they can be compared. Whoever's interested, please check out the
following, and tell me how these compare:

kernel:

git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git

virtio-net-limit-xmit-polling/base - this is net-next baseline to test against
virtio-net-limit-xmit-polling/v0 - fixes checks on out of capacity
virtio-net-limit-xmit-polling/v1 - previous revision of the patch
		this does xmit,free,xmit,2*free,free
virtio-net-limit-xmit-polling/v2 - new revision of the patch
		this does free,xmit,2*free,free

There's also this on top:
virtio-net-limit-xmit-polling/v3 -> don't delay avail index update
I don't think it's important to test this one, yet

Userspace to use: event index work is not yet merged upstream
so the revision to use is still this:
git://git.kernel.org/pub/scm/linux/kernel/git/mst/qemu-kvm.git
virtio-net-event-idx-v3

-- 
MST

Re: RFT: virtio_net: limit xmit polling

[Tom Lendacky]

On Sunday, June 19, 2011 05:27:00 AM Michael S. Tsirkin wrote:
> OK, different people seem to test different trees.  In the hope to get
> everyone on the same page, I created several variants of this patch so
> they can be compared. Whoever's interested, please check out the
> following, and tell me how these compare:

I'm in the process of testing these patches.  Base and v0 are complete
and v1 is near complete with v2 to follow.  I'm testing with a variety
of TCP_RR and TCP_STREAM/TCP_MAERTS tests involving local guest-to-guest
tests and remote host-to-guest tests.  I'll post the results in the next
day or two when the tests finish.

Thanks,
Tom

> 
> kernel:
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git
> 
> virtio-net-limit-xmit-polling/base - this is net-next baseline to test
> against virtio-net-limit-xmit-polling/v0 - fixes checks on out of capacity
> virtio-net-limit-xmit-polling/v1 - previous revision of the patch
> 		this does xmit,free,xmit,2*free,free
> virtio-net-limit-xmit-polling/v2 - new revision of the patch
> 		this does free,xmit,2*free,free
> 
> There's also this on top:
> virtio-net-limit-xmit-polling/v3 -> don't delay avail index update
> I don't think it's important to test this one, yet
> 
> Userspace to use: event index work is not yet merged upstream
> so the revision to use is still this:
> git://git.kernel.org/pub/scm/linux/kernel/git/mst/qemu-kvm.git
> virtio-net-event-idx-v3

Re: RFT: virtio_net: limit xmit polling

[Tom Lendacky]

[-- Attachment #1: Type: Text/Plain, Size: 6384 bytes --]

On Sunday, June 19, 2011 05:27:00 AM Michael S. Tsirkin wrote:
> OK, different people seem to test different trees.  In the hope to get
> everyone on the same page, I created several variants of this patch so
> they can be compared. Whoever's interested, please check out the
> following, and tell me how these compare:
> 
> kernel:
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git
> 
> virtio-net-limit-xmit-polling/base - this is net-next baseline to test
> against virtio-net-limit-xmit-polling/v0 - fixes checks on out of capacity
> virtio-net-limit-xmit-polling/v1 - previous revision of the patch
> 		this does xmit,free,xmit,2*free,free
> virtio-net-limit-xmit-polling/v2 - new revision of the patch
> 		this does free,xmit,2*free,free
> 

Here's a summary of the results.  I've also attached an ODS format spreadsheet
(30 KB in size) that might be easier to analyze and also has some pinned VM
results data.  I broke the tests down into a local guest-to-guest scenario
and a remote host-to-guest scenario.

Within the local guest-to-guest scenario I ran:
  - TCP_RR tests using two different messsage sizes and four different
    instance counts among 1 pair of VMs and 2 pairs of VMs.
  - TCP_STREAM tests using four different message sizes and two different
    instance counts among 1 pair of VMs and 2 pairs of VMs.

Within the remote host-to-guest scenario I ran:
  - TCP_RR tests using two different messsage sizes and four different
    instance counts to 1 VM and 4 VMs.
  - TCP_STREAM and TCP_MAERTS tests using four different message sizes and
    two different instance counts to 1 VM and 4 VMs.
over a 10GbE link.

*** Local Guest-to-Guest ***

Here's the local guest-to-guest summary for 1 VM pair doing TCP_RR with
256/256 request/response message size in transactions per second:

Instances	Base		V0		V1		V2
1		 8,151.56	 8,460.72	 8,439.16	 9,990.37
25		48,761.74	51,032.62	51,103.25	49,533.52
50		55,687.38	55,974.18	56,854.10	54,888.65
100		58,255.06	58,255.86	60,380.90	59,308.36

Here's the local guest-to-guest summary for 2 VM pairs doing TCP_RR with
256/256 request/response message size in transactions per second:

Instances	Base		V0		V1		V2
1		18,758.48	19,112.50	18,597.07	19,252.04
25		80,500.50	78,801.78	80,590.68	78,782.07
50		80,594.20	77,985.44	80,431.72	77,246.90
100		82,023.23	81,325.96	81,303.32	81,727.54

Here's the local guest-to-guest summary for 1 VM pair doing TCP_STREAM with
256, 1K, 4K and 16K message size in Mbps:

256:
Instances	Base		V0		V1		V2
1		   961.78	 1,115.92	   794.02	   740.37
4		 2,498.33	 2,541.82	 2,441.60	 2,308.26

1K:					
1		 3,476.61	 3,522.02	 2,170.86	 1,395.57
4		 6,344.30	 7,056.57	 7,275.16	 7,174.09

4K:					
1		 9,213.57	10,647.44	 9,883.42	 9,007.29
4		11,070.66	11,300.37	11,001.02	12,103.72

16K:
1		12,065.94	 9,437.78	11,710.60	 6,989.93
4		12,755.28	13,050.78	12,518.06	13,227.33

Here's the local guest-to-guest summary for 2 VM pairs doing TCP_STREAM with
256, 1K, 4K and 16K message size in Mbps:

256:
Instances	Base		V0		V1		V2
1		 2,434.98	 2,403.23	 2,308.69	 2,261.35
4		 5,973.82	 5,729.48	 5,956.76	 5,831.86

1K:
1		 5,305.99	 5,148.72	 4,960.67	 5,067.76
4		10,628.38	10,649.49	10,098.90	10,380.09

4K:
1		11,577.03	10,710.33	11,700.53	10,304.09
4		14,580.66	14,881.38	14,551.17	15,053.02

16K:
1		16,801.46	16,072.50	15,773.78	15,835.66
4		17,194.00	17,294.02	17,319.78	17,121.09


*** Remote Host-to-Guest ***

Here's the remote host-to-guest summary for 1 VM doing TCP_RR with
256/256 request/response message size in transactions per second:

Instances	Base		V0		V1		V2
1		 9,732.99	10,307.98	10,529.82	 8,889.28
25		43,976.18	49,480.50	46,536.66	45,682.38
50		63,031.33	67,127.15	60,073.34	65,748.62
100		64,778.43	65,338.07	66,774.12	69,391.22

Here's the remote host-to-guest summary for 4 VMs doing TCP_RR with
256/256 request/response message size in transactions per second:

Instances	Base		V0		V1		V2
1		 39,270.42	 38,253.60	 39,353.10	 39,566.33
25		207,120.91	207,964.50	211,539.70	213,882.21
50		218,801.54	221,490.56	220,529.48	223,594.25
100		218,432.62	215,061.44	222,011.61	223,480.47

Here's the remote host-to-guest summary for 1 VM doing TCP_STREAM with
256, 1K, 4K and 16K message size in Mbps:

256:
Instances	Base		V0		V1		V2
1		2,274.74	2,220.38	2,245.26	2,212.30
4		5,689.66	5,953.86	5,984.80	5,827.94

1K:
1		7,804.38	7,236.29	6,716.58	7,485.09
4		7,722.42	8,070.38	7,700.45	7,856.76

4K:
1		8,976.14	9,026.77	9,147.32	9,095.58
4		7,532.25	7,410.80	7,683.81	7,524.94

16K:
1		8,991.61	9,045.10	9,124.58	9,238.34
4		7,406.10	7,626.81	7,711.62	7,345.37

Here's the remote host-to-guest summary for 1 VM doing TCP_MAERTS with
256, 1K, 4K and 16K message size in Mbps:

256:
Instances	Base		V0		V1		V2
1		1,165.69	1,181.92	1,152.20	1,104.68
4		2,580.46	2,545.22	2,436.30	2,601.74

1K:
1		2,393.34	2,457.22	2,128.86	2,258.92
4		7,152.57	7,606.60	8,004.64	7,576.85

4K:
1		9,258.93	8,505.06	9,309.78	9,215.05
4		9,374.20	9,363.48	9,372.53	9,352.00

16K:
1		9,244.70	9,287.72	9,298.60	9,322.28
4		9,380.02	9,347.50	9,377.46	9,372.98

Here's the remote host-to-guest summary for 4 VMs doing TCP_STREAM with
256, 1K, 4K and 16K message size in Mbps:

256:
Instances	Base		V0		V1		V2
1		9,392.37	9,390.74	9,395.58	9,392.46
4		9,394.24	9,394.46	9,395.42	9,394.05

1K:
1		9,396.34	9,397.46	9,396.64	9,443.26
4		9,397.14	9,402.25	9,398.67	9,391.09

4K:
1		9,397.16	9,398.07	9,397.30	9,396.33
4		9,395.64	9,400.25	9,397.54	9,397.75

16K:
1		9,396.58	9,397.01	9,397.58	9,397.70
4		9,399.15	9,400.02	9,399.66	9,400.16


Here's the remote host-to-guest summary for 4 VMs doing TCP_MAERTS with
256, 1K, 4K and 16K message size in Mbps:

256:
Instances	Base		V0		V1		V2
1		5,048.66	5,007.26	5,074.98	4,974.86
4		9,217.23	9,245.14	9,263.97	9,294.23

1K:
1		9,378.32	9,387.12	9,386.21	9,361.55
4		9,384.42	9,384.02	9,385.50	9,385.55

4K:
1		9,391.10	9,390.28	9,389.70	9,391.02
4		9,384.38	9,383.39	9,384.74	9,384.19

16K:
1		9,390.77	9,389.62	9,388.07	9,388.19
4		9,381.86	9,382.37	9,385.54	9,383.88


Tom

> There's also this on top:
> virtio-net-limit-xmit-polling/v3 -> don't delay avail index update
> I don't think it's important to test this one, yet
> 
> Userspace to use: event index work is not yet merged upstream
> so the revision to use is still this:
> git://git.kernel.org/pub/scm/linux/kernel/git/mst/qemu-kvm.git
> virtio-net-event-idx-v3

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Re: RFT: virtio_net: limit xmit polling

[Michael S. Tsirkin]

On Tue, Jun 28, 2011 at 11:08:07AM -0500, Tom Lendacky wrote:
> On Sunday, June 19, 2011 05:27:00 AM Michael S. Tsirkin wrote:
> > OK, different people seem to test different trees.  In the hope to get
> > everyone on the same page, I created several variants of this patch so
> > they can be compared. Whoever's interested, please check out the
> > following, and tell me how these compare:
> > 
> > kernel:
> > 
> > git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git
> > 
> > virtio-net-limit-xmit-polling/base - this is net-next baseline to test
> > against virtio-net-limit-xmit-polling/v0 - fixes checks on out of capacity
> > virtio-net-limit-xmit-polling/v1 - previous revision of the patch
> > 		this does xmit,free,xmit,2*free,free
> > virtio-net-limit-xmit-polling/v2 - new revision of the patch
> > 		this does free,xmit,2*free,free
> > 
> 
> Here's a summary of the results.  I've also attached an ODS format spreadsheet
> (30 KB in size) that might be easier to analyze and also has some pinned VM
> results data.  I broke the tests down into a local guest-to-guest scenario
> and a remote host-to-guest scenario.
> 
> Within the local guest-to-guest scenario I ran:
>   - TCP_RR tests using two different messsage sizes and four different
>     instance counts among 1 pair of VMs and 2 pairs of VMs.
>   - TCP_STREAM tests using four different message sizes and two different
>     instance counts among 1 pair of VMs and 2 pairs of VMs.
> 
> Within the remote host-to-guest scenario I ran:
>   - TCP_RR tests using two different messsage sizes and four different
>     instance counts to 1 VM and 4 VMs.
>   - TCP_STREAM and TCP_MAERTS tests using four different message sizes and
>     two different instance counts to 1 VM and 4 VMs.
> over a 10GbE link.

roprabhu, Tom,

Thanks very much for the testing. So on the first glance
one seems to see a significant performance gain in V0 here,
and a slightly less significant in V2, with V1
being worse than base. But I'm afraid that's not the
whole story, and we'll need to work some more to
know what really goes on, please see below.


Some comments on the results: I found out that V0 because of mistake
on my part was actually almost identical to base.
I pushed out virtio-net-limit-xmit-polling/v1a instead that
actually does what I intended to check. However,
the fact we get such a huge distribution in the results by Tom
most likely means that the noise factor is very large.


>From my experience one way to get stable results is to
divide the throughput by the host CPU utilization
(measured by something like mpstat).
Sometimes throughput doesn't increase (e.g. guest-host)
by CPU utilization does decrease. So it's interesting.


Another issue is that we are trying to improve the latency
of a busy queue here. However STREAM/MAERTS tests ignore the latency
(more or less) while TCP_RR by default runs a single packet per queue.
Without arguing about whether these are practically interesting
workloads, these results are thus unlikely to be significantly affected
by the optimization in question.

What we are interested in, thus, is either TCP_RR with a -b flag
(configure with  --enable-burst) or multiple concurrent
TCP_RRs.



> *** Local Guest-to-Guest ***
> 
> Here's the local guest-to-guest summary for 1 VM pair doing TCP_RR with
> 256/256 request/response message size in transactions per second:
> 
> Instances	Base		V0		V1		V2
> 1		 8,151.56	 8,460.72	 8,439.16	 9,990.37
> 25		48,761.74	51,032.62	51,103.25	49,533.52
> 50		55,687.38	55,974.18	56,854.10	54,888.65
> 100		58,255.06	58,255.86	60,380.90	59,308.36
> 
> Here's the local guest-to-guest summary for 2 VM pairs doing TCP_RR with
> 256/256 request/response message size in transactions per second:
> 
> Instances	Base		V0		V1		V2
> 1		18,758.48	19,112.50	18,597.07	19,252.04
> 25		80,500.50	78,801.78	80,590.68	78,782.07
> 50		80,594.20	77,985.44	80,431.72	77,246.90
> 100		82,023.23	81,325.96	81,303.32	81,727.54
> 
> Here's the local guest-to-guest summary for 1 VM pair doing TCP_STREAM with
> 256, 1K, 4K and 16K message size in Mbps:
> 
> 256:
> Instances	Base		V0		V1		V2
> 1		   961.78	 1,115.92	   794.02	   740.37
> 4		 2,498.33	 2,541.82	 2,441.60	 2,308.26
> 
> 1K:					
> 1		 3,476.61	 3,522.02	 2,170.86	 1,395.57
> 4		 6,344.30	 7,056.57	 7,275.16	 7,174.09
> 
> 4K:					
> 1		 9,213.57	10,647.44	 9,883.42	 9,007.29
> 4		11,070.66	11,300.37	11,001.02	12,103.72
> 
> 16K:
> 1		12,065.94	 9,437.78	11,710.60	 6,989.93
> 4		12,755.28	13,050.78	12,518.06	13,227.33
> 
> Here's the local guest-to-guest summary for 2 VM pairs doing TCP_STREAM with
> 256, 1K, 4K and 16K message size in Mbps:
> 
> 256:
> Instances	Base		V0		V1		V2
> 1		 2,434.98	 2,403.23	 2,308.69	 2,261.35
> 4		 5,973.82	 5,729.48	 5,956.76	 5,831.86
> 
> 1K:
> 1		 5,305.99	 5,148.72	 4,960.67	 5,067.76
> 4		10,628.38	10,649.49	10,098.90	10,380.09
> 
> 4K:
> 1		11,577.03	10,710.33	11,700.53	10,304.09
> 4		14,580.66	14,881.38	14,551.17	15,053.02
> 
> 16K:
> 1		16,801.46	16,072.50	15,773.78	15,835.66
> 4		17,194.00	17,294.02	17,319.78	17,121.09
> 
> 
> *** Remote Host-to-Guest ***
> 
> Here's the remote host-to-guest summary for 1 VM doing TCP_RR with
> 256/256 request/response message size in transactions per second:
> 
> Instances	Base		V0		V1		V2
> 1		 9,732.99	10,307.98	10,529.82	 8,889.28
> 25		43,976.18	49,480.50	46,536.66	45,682.38
> 50		63,031.33	67,127.15	60,073.34	65,748.62
> 100		64,778.43	65,338.07	66,774.12	69,391.22
> 
> Here's the remote host-to-guest summary for 4 VMs doing TCP_RR with
> 256/256 request/response message size in transactions per second:
> 
> Instances	Base		V0		V1		V2
> 1		 39,270.42	 38,253.60	 39,353.10	 39,566.33
> 25		207,120.91	207,964.50	211,539.70	213,882.21
> 50		218,801.54	221,490.56	220,529.48	223,594.25
> 100		218,432.62	215,061.44	222,011.61	223,480.47
> 
> Here's the remote host-to-guest summary for 1 VM doing TCP_STREAM with
> 256, 1K, 4K and 16K message size in Mbps:
> 
> 256:
> Instances	Base		V0		V1		V2
> 1		2,274.74	2,220.38	2,245.26	2,212.30
> 4		5,689.66	5,953.86	5,984.80	5,827.94
> 
> 1K:
> 1		7,804.38	7,236.29	6,716.58	7,485.09
> 4		7,722.42	8,070.38	7,700.45	7,856.76
> 
> 4K:
> 1		8,976.14	9,026.77	9,147.32	9,095.58
> 4		7,532.25	7,410.80	7,683.81	7,524.94
> 
> 16K:
> 1		8,991.61	9,045.10	9,124.58	9,238.34
> 4		7,406.10	7,626.81	7,711.62	7,345.37
> 
> Here's the remote host-to-guest summary for 1 VM doing TCP_MAERTS with
> 256, 1K, 4K and 16K message size in Mbps:
> 
> 256:
> Instances	Base		V0		V1		V2
> 1		1,165.69	1,181.92	1,152.20	1,104.68
> 4		2,580.46	2,545.22	2,436.30	2,601.74
> 
> 1K:
> 1		2,393.34	2,457.22	2,128.86	2,258.92
> 4		7,152.57	7,606.60	8,004.64	7,576.85
> 
> 4K:
> 1		9,258.93	8,505.06	9,309.78	9,215.05
> 4		9,374.20	9,363.48	9,372.53	9,352.00
> 
> 16K:
> 1		9,244.70	9,287.72	9,298.60	9,322.28
> 4		9,380.02	9,347.50	9,377.46	9,372.98
> 
> Here's the remote host-to-guest summary for 4 VMs doing TCP_STREAM with
> 256, 1K, 4K and 16K message size in Mbps:
> 
> 256:
> Instances	Base		V0		V1		V2
> 1		9,392.37	9,390.74	9,395.58	9,392.46
> 4		9,394.24	9,394.46	9,395.42	9,394.05
> 
> 1K:
> 1		9,396.34	9,397.46	9,396.64	9,443.26
> 4		9,397.14	9,402.25	9,398.67	9,391.09
> 
> 4K:
> 1		9,397.16	9,398.07	9,397.30	9,396.33
> 4		9,395.64	9,400.25	9,397.54	9,397.75
> 
> 16K:
> 1		9,396.58	9,397.01	9,397.58	9,397.70
> 4		9,399.15	9,400.02	9,399.66	9,400.16
> 
> 
> Here's the remote host-to-guest summary for 4 VMs doing TCP_MAERTS with
> 256, 1K, 4K and 16K message size in Mbps:
> 
> 256:
> Instances	Base		V0		V1		V2
> 1		5,048.66	5,007.26	5,074.98	4,974.86
> 4		9,217.23	9,245.14	9,263.97	9,294.23
> 
> 1K:
> 1		9,378.32	9,387.12	9,386.21	9,361.55
> 4		9,384.42	9,384.02	9,385.50	9,385.55
> 
> 4K:
> 1		9,391.10	9,390.28	9,389.70	9,391.02
> 4		9,384.38	9,383.39	9,384.74	9,384.19
> 
> 16K:
> 1		9,390.77	9,389.62	9,388.07	9,388.19
> 4		9,381.86	9,382.37	9,385.54	9,383.88
> 
> 
> Tom
> 
> > There's also this on top:
> > virtio-net-limit-xmit-polling/v3 -> don't delay avail index update
> > I don't think it's important to test this one, yet
> > 
> > Userspace to use: event index work is not yet merged upstream
> > so the revision to use is still this:
> > git://git.kernel.org/pub/scm/linux/kernel/git/mst/qemu-kvm.git
> > virtio-net-event-idx-v3

Re: RFT: virtio_net: limit xmit polling

[Roopa Prabhu]

On 6/29/11 1:42 AM, "Michael S. Tsirkin" <mst@redhat.com> wrote:

> On Tue, Jun 28, 2011 at 11:08:07AM -0500, Tom Lendacky wrote:
>> On Sunday, June 19, 2011 05:27:00 AM Michael S. Tsirkin wrote:
>>> OK, different people seem to test different trees.  In the hope to get
>>> everyone on the same page, I created several variants of this patch so
>>> they can be compared. Whoever's interested, please check out the
>>> following, and tell me how these compare:
>>> 
>>> kernel:
>>> 
>>> git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git
>>> 
>>> virtio-net-limit-xmit-polling/base - this is net-next baseline to test
>>> against virtio-net-limit-xmit-polling/v0 - fixes checks on out of capacity
>>> virtio-net-limit-xmit-polling/v1 - previous revision of the patch
>>>             this does xmit,free,xmit,2*free,free
>>> virtio-net-limit-xmit-polling/v2 - new revision of the patch
>>>             this does free,xmit,2*free,free
>>> 
>> 
>> Here's a summary of the results.  I've also attached an ODS format
>> spreadsheet
>> (30 KB in size) that might be easier to analyze and also has some pinned VM
>> results data.  I broke the tests down into a local guest-to-guest scenario
>> and a remote host-to-guest scenario.
>> 
>> Within the local guest-to-guest scenario I ran:
>>   - TCP_RR tests using two different messsage sizes and four different
>>     instance counts among 1 pair of VMs and 2 pairs of VMs.
>>   - TCP_STREAM tests using four different message sizes and two different
>>     instance counts among 1 pair of VMs and 2 pairs of VMs.
>> 
>> Within the remote host-to-guest scenario I ran:
>>   - TCP_RR tests using two different messsage sizes and four different
>>     instance counts to 1 VM and 4 VMs.
>>   - TCP_STREAM and TCP_MAERTS tests using four different message sizes and
>>     two different instance counts to 1 VM and 4 VMs.
>> over a 10GbE link.
> 
> roprabhu, Tom,
> 
> Thanks very much for the testing. So on the first glance
> one seems to see a significant performance gain in V0 here,
> and a slightly less significant in V2, with V1
> being worse than base. But I'm afraid that's not the
> whole story, and we'll need to work some more to
> know what really goes on, please see below.
> 
> 
> Some comments on the results: I found out that V0 because of mistake
> on my part was actually almost identical to base.
> I pushed out virtio-net-limit-xmit-polling/v1a instead that
> actually does what I intended to check. However,
> the fact we get such a huge distribution in the results by Tom
> most likely means that the noise factor is very large.
> 
> 
> From my experience one way to get stable results is to
> divide the throughput by the host CPU utilization
> (measured by something like mpstat).
> Sometimes throughput doesn't increase (e.g. guest-host)
> by CPU utilization does decrease. So it's interesting.
> 
> 
> Another issue is that we are trying to improve the latency
> of a busy queue here. However STREAM/MAERTS tests ignore the latency
> (more or less) while TCP_RR by default runs a single packet per queue.
> Without arguing about whether these are practically interesting
> workloads, these results are thus unlikely to be significantly affected
> by the optimization in question.
> 
> What we are interested in, thus, is either TCP_RR with a -b flag
> (configure with  --enable-burst) or multiple concurrent
> TCP_RRs.
> 
> 
> 
Michael, below are some numbers I got from one round of runs.
Thanks,
Roopa

256byte req/response.
Vcpus and irqs were pinned to 4 cores and the cpu utilization is
Avg across 4 cores.

base:
Numof concurrent TCP_RRs    Num of transactions/sec  host cpu-util(%)
1                            7982.93                        15.72
25                           67873                         28.84
50                           112534                        52.25
100                          192057                       86.54


v1
Numof concurrent TCP_RRs    Num of transactions/sec    host cpu-util(%)
1                           7970.94                       10.8
25                          65496.8                       28
50                          109858                        53.22
100                         190155                        87.5


v1a
Numof concurrent TCP_RRs    Num of transactions/sec   host cpu-util (%)
1                           7979.81                       9.5
25                          66786.1                       28
50                          109552                        51
100                         190876                        88


v2
Numof concurrent TCP_RRs    Num of transactions/sec   host cpu-util (%)
1                            7969.87                     16.5
25                           67780.1                     28.44
50                           114966                      54.29
100                          177982                      79.9

Re: RFT: virtio_net: limit xmit polling

[Michael S. Tsirkin]

On Thu, Jul 14, 2011 at 12:38:05PM -0700, Roopa Prabhu wrote:
> Michael, below are some numbers I got from one round of runs.
> Thanks,
> Roopa

Thanks!
At this point it does not appear like there's any measureable
impact from moving the polling around.

-- 
MST