Re: [patch 04/17] Add pagetable accessors to pack and unpack pagetable entries

Jeremy Fitzhardinge
2007-04-04T09:26:13Z

Andi Kleen wrote:
> What do the benchmarks say with CONFIG_PARAVIRT on native hardware
> compared to !CONFIG_PARAVIRT. e.g. does lmbench suffer?

Barely. There's a slight hit for not using patching, and patching is
almost identical to native performance. The most noticeable difference
is in the null syscall microbenchmark, but once you get to complex
things the difference is in the noise.

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
--------- ------------- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ----
non-paravirt
ezr Linux 2.6.21- 1000 0.25 0.52 31.6 34.7 10.3 1.03 5.31 726. 1565 4520
ezr Linux 2.6.21- 1000 0.25 0.52 31.8 34.7 12.6 1.03 5.41 725. 1564 4585
ezr Linux 2.6.21- 1000 0.25 0.55 31.7 34.5 11.8 1.02 5.47 720. 1595 4518

paravirt, no patching
ezr Linux 2.6.21- 1000 0.28 0.55 31.3 34.3 10.0 1.05 5.56 747. 1621 4675
ezr Linux 2.6.21- 1000 0.28 0.56 31.5 34.3 12.9 1.05 5.66 755. 1629 4684
ezr Linux 2.6.21- 1000 0.28 0.55 31.8 34.5 12.5 1.05 5.45 747. 1622 4695

paravirt, patching
ezr Linux 2.6.21- 1000 0.25 0.53 31.8 34.4 10.1 1.04 5.44 730. 1583 4600
ezr Linux 2.6.21- 1000 0.26 0.55 32.1 35.2 13.3 1.03 5.48 748. 1589 4606
ezr Linux 2.6.21- 1000 0.26 0.54 32.0 34.9 14.1 1.04 5.43 752. 1606 4647

J