Re: Waiting for bufdaemon

From: Yasuhiro Kimura <yasu_at_utahime.org>
Subject: Re: Waiting for bufdaemon
Date: Thu, 28 Jan 2021 05:02:42 +0900 (JST)

> It took for a while to investigate, but according to the result of
> bisect following commit is the source of problem in my case.
> 
> ----------------------------------------------------------------------
> commit 84eaf2ccc6a
> Author: Konstantin Belousov <kib_at_FreeBSD.org>
> Date:   Mon Dec 21 19:02:31 2020 +0200
> 
>     x86: stop punishing VMs with low priority for TSC timecounter
>     
>     I suspect that virtualization techniques improved from the time when we
>     have to effectively disable TSC use in VM.  For instance, it was reported
>     (complained) in https://github.com/JuliaLang/julia/issues/38877 that
>     FreeBSD is groundlessly slow on AWS with some loads.
>     
>     Remove the check and start watching for complaints.
>     
>     Reviewed by:    emaste, grehan
>     Discussed with: cperciva
>     Sponsored by:   The FreeBSD Foundation
>     Differential Revision:  https://reviews.freebsd.org/D27629
> ----------------------------------------------------------------------
> 
> I confirmed the problem still happens with 5c325977b11 but reverting
> above commit fixes it.

I submitted this problem to Bugzilla.

Timeout of bufdaemon happens at shutdown time with -CURRENT amd64 and VirtulaBox VM
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=253087

---
Yasuhiro Kimura