Date: Tue, 30 Nov 2021 19:08:08 +0200 From: Andriy Gapon <avg@freebsd.org> To: Kyle Evans <kevans@freebsd.org> Cc: src-committers <src-committers@freebsd.org>, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: 3d9d64aa1846 - main - kern_tc: unify timecounter to bintime delta conversion Message-ID: <69d4804d-1d94-7757-5c93-0d062f9c31c0@FreeBSD.org> In-Reply-To: <CACNAnaGzuJuj_eZxA3y2vGrermmhH7BWkaa2OJv_WWtGXs98Zw@mail.gmail.com> References: <202111301334.1AUDYJEU014078@gitrepo.freebsd.org> <CACNAnaGzuJuj_eZxA3y2vGrermmhH7BWkaa2OJv_WWtGXs98Zw@mail.gmail.com>
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On 30/11/2021 18:14, Kyle Evans wrote: > I wonder if this helps explain the behavior we saw when enabling TSC > on VirtualBox guests. Threads doing small ~1 second or less sleeps > would start to miss their wakeups, so we'd consistently see, e.g., > shutdown issues after applying a high loading while we're waiting for > bufdaemon threads. It very well may be the case. The reason I arrived at this change is that we also sometimes saw the same problem but on VMWware. That prompted me to add some diagnostic code to sleepqueue to turn those missed wakeups into panics. As kib pointed out, mav recently made a change that would mask the problem as a side effect: https://cgit.FreeBSD.org/src/commit/?id=6df1359e5542f69179c142be1ea099d447e273d1 But I wanted to fix the root cause anyway. -- Andriy Gapon
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