On Mon, Jan 2, 2017 at 7:17 PM, Neal Cardwell <ncardw...@google.com> wrote:
> On Mon, Jan 2, 2017 at 12:05 AM, Sedat Dilek <sedat.di...@gmail.com> wrote:
>>
>> Hi,
>>
>> I am trying to force the set of BBR congestion control as default.
>> My old linux-config uses CUBIC as default.
>> I want both BBR and CUBIC to be built but BBR shall be my default.
>>
>> I tried the below snippet.
>>
>> I refresh my new linux-config like this...
>>
>> $ MAKE="make V=1" ; COMPILER="mycompiler" ; MAKE_OPTS="CC=$COMPILER
>> HOSTCC=$COMPILER" ; yes "" | $MAKE $MAKE_OPTS oldconfig && $MAKE
>> $MAKE_OPTS silentoldconfig < /dev/null
>>
>> What am I doing wrong?
>
> Perhaps your build directory already has an old .config file that sets
> the DEFAULT_TCP_CONG to be "cubic", and your "make oldconfig" and
> "make silentoldconfig" are maintaining those lines from the old
> .config?
>
> If you want to start with your existing .config but then make BBR the
> default, then it might be simplest just to edit your .config directly:
>
> -CONFIG_DEFAULT_TCP_CONG="cubic"
> +CONFIG_DEFAULT_TCP_CONG="bbr"
>
Just to clarify...
I can have both TCP_CONG cubic and bbr built and switch for example via sysctl?
Which tc version is required?
Here tc is from iproute (20121211-2~precise).
Is that enough?
> BTW, I presume you have seen the warning in the BBR commit message or
> tcp_bbr.c about ensuring that BBR is used with the "fq" qdisc:
>
> NOTE: BBR *must* be used with the fq qdisc ("man tc-fq") with pacing
> enabled, since pacing is integral to the BBR design and
> implementation. BBR without pacing would not function properly, and
> may incur unnecessary high packet loss rates.
>
> The BBR quick-start guide has some details about how to build and
> enable BBR and fq:
>
> https://github.com/google/bbr/blob/master/Documentation/bbr-quick-start.md
>
Hmmm...
>From [1] Section "Further reading"...
egrep '(CONFIG_TCP_CONG_BBR|CONFIG_NET_SCH_FQ)=' .config
then you see exactly the following lines:
CONFIG_TCP_CONG_BBR=y
CONFIG_NET_SCH_FQ=y
Should CONFIG_TCP_CONG_BBR have a "select CONFIG_NET_SCH_FQ" in its Kconfig?
That would be safer.
[1] https://github.com/google/bbr/blob/master/Documentation/bbr-quick-start.md
> Hope that helps,
Thanks you reply helped for further testings.
- Sedat -
P.S.: Note2myself: Enable NET_SCH_FQ
$ ./scripts/diffconfig /boot/config-4.9.0-2-iniza-amd64 .config
NET_SCH_FQ n -> y
