Re: [Bloat] Initial tests with BBR in kernel 4.9

[Eric Dumazet <eric.dumazet@gmail.com>]

I do not know any particular issues with FQ in VM

If you have a recent tc binary (iproute2 package) you can get some
infos, as mentioned in this commit changelog :

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=fefa569a9d4bc4b7758c0fddd75bb0382c95da77


$ tc -s qd sh dev eth0 | grep latency
0 gc, 0 highprio, 32490767 throttled, 2382 ns latency 


On Wed, 2017-01-25 at 22:31 +0100, Hans-Kristian Bakke wrote:
> kvm-clock is a paravirtualized clock that seems to use the CPUs TSC
> capabilities if they exist. But it may not be perfect:
> 
> 
> https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization_Host_Configuration_and_Guest_Installation_Guide/chap-Virtualization_Host_Configuration_and_Guest_Installation_Guide-KVM_guest_timing_management.html
> 
> 
> On 25 January 2017 at 22:29, Hans-Kristian Bakke <hkbakke@gmail.com>
> wrote:
>         Actually I think that is because it may be using the newer
>         TSC:
>          dmesg | grep clocksource
>         [    0.000000] clocksource: kvm-clock: mask:
>         0xffffffffffffffff max_cycles: 0x1cd42e4dffb, max_idle_ns:
>         881590591483 ns
>         [    0.000000] clocksource: refined-jiffies: mask: 0xffffffff
>         max_cycles: 0xffffffff, max_idle_ns: 7645519600211568 ns
>         [    0.000000] clocksource: hpet: mask: 0xffffffff max_cycles:
>         0xffffffff, max_idle_ns: 19112604467 ns
>         [    0.092665] clocksource: jiffies: mask: 0xffffffff
>         max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns
>         [    0.366429] clocksource: Switched to clocksource kvm-clock
>         [    0.378974] clocksource: acpi_pm: mask: 0xffffff
>         max_cycles: 0xffffff, max_idle_ns: 2085701024 ns
>         [    1.666474] tsc: Refined TSC clocksource calibration:
>         3200.013 MHz
>         [    1.666479] clocksource: tsc: mask: 0xffffffffffffffff
>         max_cycles: 0x2e20562a1bb, max_idle_ns: 440795285529 ns
>         
>         
>         
>         On 25 January 2017 at 22:26, Jonathan Morton
>         <chromatix99@gmail.com> wrote:
>                 
>                 > On 25 Jan, 2017, at 23:20, Hans-Kristian Bakke
>                 <hkbakke@gmail.com> wrote:
>                 >
>                 > ​[    0.000000] ACPI: HPET 0x00000000BFFE274F 000038
>                 (v01 BOCHS  BXPCHPET 00000001 BXPC 00000001)
>                 > [    0.000000] ACPI: HPET id: 0x8086a201 base:
>                 0xfed00000
>                 > [    0.000000] clocksource: hpet: mask: 0xffffffff
>                 max_cycles: 0xffffffff, max_idle_ns: 19112604467 ns
>                 > [    0.000000] hpet clockevent registered
>                 > [    0.362335] hpet0: at MMIO 0xfed00000, IRQs 2, 8,
>                 0
>                 > [    0.362339] hpet0: 3 comparators, 64-bit
>                 100.000000 MHz counter
>                 > [    0.661731] rtc_cmos 00:00: alarms up to one day,
>                 y3k, 114 bytes nvram, hpet irqs
>                 
>                 Conspicuously absent here is a line saying
>                 “clocksource: Switched to clocksource hpet”.  That may
>                 be worth examining in more detail.
>                 
>                  - Jonathan Morton
>                 
>         
>         
> 
> 
> _______________________________________________
> Bloat mailing list
> Bloat@lists.bufferbloat.net
> https://lists.bufferbloat.net/listinfo/bloat