Re: [PATCH net-next v2 2/2] selftests: fib_tests: Add a test case for IPv6 garbage collection

[Kui-Feng Lee <sinquersw@gmail.com>]

On 7/21/23 13:01, David Ahern wrote:
> On 7/21/23 12:31 PM, Kui-Feng Lee wrote:
>>>
>>> sysctl -wq net.ipv6.route.flush=1
>>>
>>> # add routes
>>> #...
>>>
>>> # delete expired routes synchronously
>>> sysctl -wq net.ipv6.route.flush=1
>>>
>>> Note that the net.ipv6.route.flush handler uses the 'old' flush value.
>>
>> May I use bpftrace to measure time spending on writing to procfs?
>> It is in the order of microseconds. time command doesn't work.
>>
> 
> Both before this patch and after this patch are in microseconds?
> 

The test case includes two parts. First part, add 1k temporary routes
only. Second part, add 5k permanent routes before adding 1k temporary
routes. In both cases, they wait for a few second and run sysctl -wq
net.ipv6.route.flush=1 to force gc. I use bpftrace to measure the time
the syscalls that write to procfs. Following are the numbers (5 times 
average) I got.

Without the patch
  1k temp w/o 5k perm: ~588us
  1k temp w/  5k perm: ~1055us
With the patch
  1k temp w/o 5k perm: ~550us
  1k temp w/  5k perm: ~561us