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* [PATCH net-next 0/3] xen-netback: switch to NAPI + kthread 1:1 model
@ 2013-08-26 11:59 Wei Liu
  2013-08-26 11:59 ` [PATCH net-next 1/3] xen-netback: remove page tracking facility Wei Liu
                   ` (4 more replies)
  0 siblings, 5 replies; 9+ messages in thread
From: Wei Liu @ 2013-08-26 11:59 UTC (permalink / raw)
  To: netdev; +Cc: xen-devel, ian.campbell, msw, konrad.wilk, annie.li, Wei Liu

This series implements NAPI + kthread 1:1 model for Xen netback.

This model
 - provides better scheduling fairness among vifs
 - is prerequisite for implementing multiqueue for Xen network driver

The second patch has the real meat:
 - make use of NAPI to mitigate interrupt
 - kthreads are not bound to CPUs any more, so that we can take
   advantage of backend scheduler and trust it to do the right thing

Benchmark is done on a Dell T3400 workstation with 4 cores, running 4
DomUs. Netserver runs in Dom0. DomUs do netperf to Dom0 with
following command: /root/netperf -H Dom0 -fm -l120

IRQs are distributed to 4 cores by hand in the new model, while in the
old model vifs are automatically distributed to 4 kthreads.

* New model
%Cpu0  :  0.5 us, 20.3 sy,  0.0 ni, 28.9 id,  0.0 wa,  0.0 hi, 24.4 si, 25.9 st
%Cpu1  :  0.5 us, 17.8 sy,  0.0 ni, 28.8 id,  0.0 wa,  0.0 hi, 27.7 si, 25.1 st
%Cpu2  :  0.5 us, 18.8 sy,  0.0 ni, 30.7 id,  0.0 wa,  0.0 hi, 22.9 si, 27.1 st
%Cpu3  :  0.0 us, 20.1 sy,  0.0 ni, 30.4 id,  0.0 wa,  0.0 hi, 22.7 si, 26.8 st
Throughputs: 2027.89 2025.95 2018.57 2016.23 aggregated: 8088.64

* Old model
%Cpu0  :  0.5 us, 68.8 sy,  0.0 ni, 16.1 id,  0.5 wa,  0.0 hi,  2.8 si, 11.5 st
%Cpu1  :  0.4 us, 45.1 sy,  0.0 ni, 31.1 id,  0.4 wa,  0.0 hi,  2.1 si, 20.9 st
%Cpu2  :  0.9 us, 44.8 sy,  0.0 ni, 30.9 id,  0.0 wa,  0.0 hi,  1.3 si, 22.2 st
%Cpu3  :  0.8 us, 46.4 sy,  0.0 ni, 28.3 id,  1.3 wa,  0.0 hi,  2.1 si, 21.1 st
Throughputs: 1899.14 2280.43 1963.33 1893.47 aggregated: 8036.37

We can see that the impact is mainly on CPU usage. The new model moves
processing from kthread to NAPI (software interrupt).

Wei Liu (3):
  xen-netback: remove page tracking facility
  xen-netback: switch to NAPI + kthread 1:1 model
  xen-netback: rename functions

 drivers/net/xen-netback/common.h    |  150 +++++--
 drivers/net/xen-netback/interface.c |  135 ++++--
 drivers/net/xen-netback/netback.c   |  833 +++++++++++------------------------
 3 files changed, 445 insertions(+), 673 deletions(-)

-- 
1.7.10.4

^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2013-08-29  5:23 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2013-08-26 11:59 [PATCH net-next 0/3] xen-netback: switch to NAPI + kthread 1:1 model Wei Liu
2013-08-26 11:59 ` [PATCH net-next 1/3] xen-netback: remove page tracking facility Wei Liu
2013-08-26 11:59 ` [PATCH net-next 2/3] xen-netback: switch to NAPI + kthread 1:1 model Wei Liu
2013-08-26 11:59 ` [PATCH net-next 3/3] xen-netback: rename functions Wei Liu
2013-08-28  9:01 ` [PATCH net-next 0/3] xen-netback: switch to NAPI + kthread 1:1 model Wei Liu
2013-08-28 14:28   ` David Miller
2013-08-28 14:41     ` Wei Liu
2013-08-28 16:08       ` David Miller
2013-08-29  5:23 ` David Miller

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