I thought people might be interested in some benchmark results I
recently recorded. I''ve appended the output of a run of the OS
micro-benchmark lmbench 3.0, comparing the performance of Linux
2.6.8.1 running native, and on Xen.
The figures show that the performance of Linux running on Xen is
very close to that of native. On many benchmarks, the overhead
of running on Xen is actually less than the overhead of an SMP
build of Linux vs a uniprocessor one. (Xen itself is SMP
capable, but each of the guest OSes must currently be
uniprocessor -- we''ll fix this post 2.0).
Xen shows some overhead on the context switch, fork, and page
fault benchmarks, but that''s the price of safe virtualisation.
Remember that these OS-intensive micro-benchmarks represent an
absolute worse case scenario for any kind of virtualization
technology. Real-world workloads will typically show rather
lower overheads (within a few percent for IO-intensive
applications like Apache and PostgreSQL, and less than 1% for
computer intensive applications like Povray etc).
Anyhow, I''m off on holiday until the 19th, so please send email
to the list rather than direct to me.
Best,
Ian
====================================================================
key:
26-nat-sm : Linux 2.6.8.1 native SMP build
26-nat-un : Linux 2.6.8.1 native uniprocessor build
26-xR1301 : Linux 2.6.8.1/xen (uniprocessor) on Xen version 1.1301
These figures were recorded on a dual processor 2.4GHz Xeon box,
with SMP Xen.
L M B E N C H 3 . 0 S U M M A R Y
------------------------------------
(Alpha software, do not distribute)
Processor, Processes - times in microseconds - smaller is better
------------------------------------------------------------------------------
Host OS Mhz null null open slct sig sig fork exec sh
call I/O stat clos TCP inst hndl proc proc proc
--------- ------------- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
26-nat-sm Linux 2.6.8.1 2400 0.49 0.62 2.25 3.72 24.3 0.90 3.49 189. 891. 3043
26-nat-un Linux 2.6.8.1 2400 0.46 0.52 1.46 2.27 5.90 0.79 2.76 114. 590. 2454
26-xR1301 Linux 2.6.8.1 2400 0.46 0.52 1.29 1.98 5.44 0.79 1.34 218. 879. 3183
Context switching - times in microseconds - smaller is better
-------------------------------------------------------------------------
Host OS 2p/0K 2p/16K 2p/64K 8p/16K 8p/64K 16p/16K 16p/64K
ctxsw ctxsw ctxsw ctxsw ctxsw ctxsw ctxsw
--------- ------------- ------ ------ ------ ------ ------ ------- -------
26-nat-sm Linux 2.6.8.1 5.5300 5.5600 5.7700 5.4500 28.7 3.83000 31.7
26-nat-un Linux 2.6.8.1 1.3400 1.4900 1.6100 2.3900 25.5 5.78000 39.2
26-xR1301 Linux 2.6.8.1 3.1600 3.4900 3.6400 4.2600 30.3 8.92000 41.3
*Local* Communication latencies in microseconds - smaller is better
---------------------------------------------------------------------
Host OS 2p/0K Pipe AF UDP RPC/ TCP RPC/ TCP
ctxsw UNIX UDP TCP conn
--------- ------------- ----- ----- ---- ----- ----- ----- ----- ----
26-nat-sm Linux 2.6.8.1 5.530 15.0 18.9 26.4 35.0 29.1 37.8 55.
26-nat-un Linux 2.6.8.1 1.340 5.449 8.79 12.0 19.9 12.7 24.2 42.
26-xR1301 Linux 2.6.8.1 3.320 8.993 16.9 18.2 26.4 19.2 30.3 53.
File & VM system latencies in microseconds - smaller is better
-------------------------------------------------------------------------------
Host OS 0K File 10K File Mmap Prot Page 100fd
Create Delete Create Delete Latency Fault Fault selct
--------- ------------- ------ ------ ------ ------ ------- ----- ------- -----
26-nat-sm Linux 2.6.8.1 41.3 19.0 96.0 38.3 134.0 0.889 2.37650 22.4
26-nat-un Linux 2.6.8.1 32.2 6.1050 69.8 15.0 84.0 0.871 1.61550 3.614
26-xR1301 Linux 2.6.8.1 32.0 5.5340 64.9 14.3 155.0 1.372 2.67530 3.016
*Local* Communication bandwidths in MB/s - bigger is better
-----------------------------------------------------------------------------
Host OS Pipe AF TCP File Mmap Bcopy Bcopy Mem Mem
UNIX reread reread (libc) (hand) read write
--------- ------------- ---- ---- ---- ------ ------ ------ ------ ---- -----
26-nat-sm Linux 2.6.8.1 705. 477. 313. 1411.8 1550.0 572.0 577.6 1536 788.3
26-nat-un Linux 2.6.8.1 1031 1646 364. 1551.4 1550.3 568.5 574.3 1548 796.8
26-xR1301 Linux 2.6.8.1 526. 1079 323. 1510.1 1568.3 550.1 550.4 1566 786.4
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