On 08/29/2015 10:59 PM, Raghavendra K T wrote:
> Please note that similar overhead was also reported while creating
> veth pairs https://lkml.org/lkml/2013/3/19/556
That got me curious, so I took the veth pair creation script from there,
and started running it out to 10K pairs, comparing a 3.14.44 kernel with
a 4.2.0-rc4+ from net-next and then net-next after pulling to get the
snmp stat aggregation perf change (4.2.0-rc8+).
Indeed, the 4.2.0-rc8+ kernel with the change was faster than the
4.2.0-rc4+ kernel without it, but both were slower than the 3.14.44 kernel.
I've put a spreadsheet with the results at:
ftp://ftp.netperf.org/vethpair/vethpair_compare.ods
A perf top for the 4.20-rc8+ kernel from the net-next tree looks like
this out around 10K pairs:
PerfTop: 11155 irqs/sec kernel:94.2% exact: 0.0% [4000Hz
cycles], (all, 32 CPUs)
-------------------------------------------------------------------------------
23.44% [kernel] [k] vsscanf
7.32% [kernel] [k] mutex_spin_on_owner.isra.4
5.63% [kernel] [k] __memcpy
5.27% [kernel] [k] __dev_alloc_name
3.46% [kernel] [k] format_decode
3.44% [kernel] [k] vsnprintf
3.16% [kernel] [k] acpi_os_write_port
2.71% [kernel] [k] number.isra.13
1.50% [kernel] [k] strncmp
1.21% [kernel] [k] _parse_integer
0.93% [kernel] [k] filemap_map_pages
0.82% [kernel] [k] put_dec_trunc8
0.82% [kernel] [k] unmap_single_vma
0.78% [kernel] [k] native_queued_spin_lock_slowpath
0.71% [kernel] [k] menu_select
0.65% [kernel] [k] clear_page
0.64% [kernel] [k] _raw_spin_lock
0.62% [kernel] [k] page_fault
0.60% [kernel] [k] find_busiest_group
0.53% [kernel] [k] snprintf
0.52% [kernel] [k] int_sqrt
0.46% [kernel] [k] simple_strtoull
0.44% [kernel] [k] page_remove_rmap
My attempts to get a call-graph have been met with very limited success.
Even though I've installed the dbg package from "make deb-pkg" the
symbol resolution doesn't seem to be working.
happy benchmarking,
rick jones
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