698541 – vhost-net/kvm need optimizations for UDP R from guest to host .

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Bug 698541 - vhost-net/kvm need optimizations for UDP R from guest to host .

Summary: vhost-net/kvm need optimizations for UDP R from guest to host .

Keywords:
Status:	CLOSED WONTFIX
Alias:	None
Product:	Red Hat Enterprise Linux 7
Classification:	Red Hat
Component:	kernel
Sub Component:
Version:	7.0
Hardware:	Unspecified
OS:	Unspecified
Priority:	medium
Severity:	medium
Target Milestone:	rc
Target Release:	7.0
Assignee:	Vlad Yasevich
QA Contact:	Virtualization Bugs
Docs Contact:
URL:
Whiteboard:
Depends On:
Blocks:	1113511
TreeView+	depends on / blocked

Reported:	2011-04-21 07:54 UTC by Quan Wenli
Modified:	2016-06-22 18:00 UTC (History)
CC List:	9 users (show)
Fixed In Version:
Doc Type:	Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed:	2016-06-22 18:00:22 UTC
Target Upstream Version:
Embargoed:

Attachments	(Terms of Use)
rhel6.1-snp1-vhost-net vs virtio-net megabyte/cpu (60.89 KB, text/html) 2011-04-21 07:54 UTC, Quan Wenli	no flags	Details
UDP results with 3.10.0-138.el7.x86_64/qemu-kvm-1.5.3-66.el7.x86_64 (51.36 KB, text/html) 2014-08-01 03:18 UTC, Quan Wenli	no flags	Details
View All

Description Quan Wenli 2011-04-21 07:54:28 UTC

Created attachment 493728 [details]
rhel6.1-snp1-vhost-net vs virtio-net megabyte/cpu

Description of problem:

1> When application doesn't flow control, megabyte/cpu shows regression (drop ) for all UDP R for guest to host.Detail info ,please check the attachment. 
2> When application does flow control, for example by rate-limiting the stream to within 10% and 30% packet drops, vhost-net doesn't have performance improvement for UDP R for guest to host compared with virtio-net.

Lost packet rate = 10% 
vhost-net 
Socket  Message  Elapsed      Messages                
Size    Size     Time         Okay Errors   Throughput
bytes   bytes    secs            #      #   10^6bits/sec
124928    1460   60.00      468000      0      91.10
124928           60.00      420001             81.76

virtio-net 
Socket  Message  Elapsed      Messages                
Size    Size     Time         Okay Errors   Throughput
bytes   bytes    secs            #      #   10^6bits/sec
124928    1460   60.00      468000      0      91.10
124928           60.00      420003             81.76

Lost packet rate = 30% 

vhost-net
Socket  Message  Elapsed      Messages                
Size    Size     Time         Okay Errors   Throughput
bytes   bytes    secs            #      #   10^6bits/sec

124928    1460   60.00      600000      0     116.80
124928           60.00      420122             81.78

virtio-net

Socket  Message  Elapsed      Messages                
Size    Size     Time         Okay Errors   Throughput
bytes   bytes    secs            #      #   10^6bits/sec

124928    1460   60.00      600000      0     116.80
124928           60.00      420029             81.77

Version-Release number of selected component (if applicable):

host:
kernel-2.6.32-125.el6.x86_64
qemu-kvm-0.12.1.2-2.152.el6.x86_64
guest:
kernel-2.6.32-125.el6.x86_64

How reproducible:


Steps to Reproduce:
1.steps for description 1 
run netserver on the guest 
run netperf ci on the host like : mpstat -P ALL 1 &>${CPU_FILE} & ssh $client $client_path -C -c -H $server -l 30 -t UDP_STREAM -- -m $packet_size && kill -9  `pgrep mpstat` 
Calculate megabyte/cpu for each packets sizes

2.steps for description 2 
Rate limit the sender and see at what rate of sender do you get some predefined loss ratio (e.g control the lost packet rate within 10% and 30%).
configurate netperf with "--enable-intervals=yes " 
Lost packet rate = 10% 
vhost-net:/root/tool/netperf-2.4.5/src/netperf -w 1 -b 78 -H 192.168.0.13 -l 60 -t UDP_STREAM -- -m 1460 
virtio-net:/root/tool/netperf-2.4.5/src/netperf -w 1 -b 78 -H 192.168.0.13 -l60 -t UDP_STREAM -- -m 1460

Lost packet rate = 30% 

vhost-net:/root/tool/netperf-2.4.5/src/netperf -w 1 -b 100 -H 192.168.0.13 -l 60 -t UDP_STREAM -- -m 1460 
virtio-net:/root/tool/netperf-2.4.5/src/netperf -w 1 -b 100 -H 192.168.0.13 -l 60 -t UDP_STREAM -- -m 1460  
  
Actual results:


Expected results:


Additional info:

Comment 2 Michael S. Tsirkin 2011-05-30 15:40:21 UTC

Basically I think to improve UDP receive speed we need something like GRO for UDP. Another thing that is reported to help here is the event index
feature. In both cases we need the code upstream first as
maintaining a forked version in rhel would be very painful.

Comment 7 Ronen Hod 2012-07-15 14:41:41 UTC

Deferring to RHEL7.
It seems as if we need to add GRO like functionality for UDP, which is too much for RHEL6.
First do it upstream.

Comment 20 Quan Wenli 2014-08-01 03:18:26 UTC

Created attachment 923057 [details]
UDP results with 3.10.0-138.el7.x86_64/qemu-kvm-1.5.3-66.el7.x86_64

Comment 21 Quan Wenli 2014-08-01 03:22:14 UTC

Re-tested it on latest rhel7 host/guest with 3.10.0-138.el7.x86_64/qemu-kvm-1.5.3-66.el7.x86_64

From atteched file UDP_Rhel7-3.10.0-138.html, we could see :

 - for samll packet ( <= 4096), 0% packet drop in both virtio-net/vhost, but host sends more UDP through virtio-net than vhost, so there is 20% around degradation through vhost.
 - for large packet ( > 4096), although host sends more (around 20%) UDP through virtio-net than vhost, but guest receive UDP more through vhost than virtio-net.

Vlad, any comments about above results, do you think we still have UDP issue with vhost?

Comment 22 Ronen Hod 2014-10-22 18:25:58 UTC

Things improved, but still requires some follow-up/investigation. Deferring to 7.2.

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