Date: Thu, 21 Oct 2010 20:43:01 +0300 From: Jaakko Heinonen <jh@FreeBSD.org> To: Alexander Motin <mav@FreeBSD.org> Cc: Marius =?utf-8?Q?N=C3=BCnnerich?= <marius@nuenneri.ch>, Poul-Henning Kamp <phk@phk.freebsd.dk>, freebsd-geom@freebsd.org Subject: Re: Hyperactive g_event thread Message-ID: <20101021174301.GA1381@a91-153-123-205.elisa-laajakaista.fi> In-Reply-To: <4C4F171C.9010106@FreeBSD.org> References: <4C4ED619.7050305@FreeBSD.org> <27237.1280241532@critter.freebsd.dk> <AANLkTi=uRPV2T0=t_1s=Jc4PmBtai=__HqhCtYpiDdTQ@mail.gmail.com> <AANLkTikvV4oymBBA%2B_0zbzd_edS8dRfqqJRODE0989%2Bn@mail.gmail.com> <4C4F171C.9010106@FreeBSD.org>
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Hi, On 2010-07-27, Alexander Motin wrote: > Marius Nünnerich wrote: > > On Tue, Jul 27, 2010 at 18:07, Marius Nünnerich <marius@nuenneri.ch> wrote: > >> I was running with a patch that removed the timeout for a while like 2 > >> years ago. Albeit not with high load. Worked fine at that time, I will > >> search for the patch when I'm back home later today. > >> > > Here it is: > > http://lists.freebsd.org/pipermail/freebsd-geom/2008-December/003200.html > > The mail is quite old now, I don't know if the patch still applies. http://nuenneri.ch/freebsd/geom_tl2.patch > Yes, I was thinking about something like that. Patch mostly applies now > and even builds. May be I would just put there sx_sleep() instead if > msleep(), as topology_lock is sx. > > Could somebody to review this and tell how correct is to not drop > topology lock between events handling and could there be places where > g_wait_event woken without holding topology_lock? I looked at this patch. g_post_event_x() and possibly g_orphan_provider() may wake g_wait_event up without holding the topology lock. g_do_wither() also lacks an assert for the lock although I guess that it's always held there. Thus I don't consider the patch being correct. I drafted a patch to use g_eventlock instead to protect against losing wakeups: http://people.freebsd.org/~jh/patches/geom-eventproc-sleep.diff Reviews and/or testing will be welcomed. -- Jaakko
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