Date: Tue, 14 May 2013 18:08:45 +0200 From: =?ISO-8859-1?Q?Roger_Pau_Monn=E9?= <roger.pau@citrix.com> To: Konstantin Belousov <kostikbel@gmail.com> Cc: "current@freebsd.org" <current@freebsd.org> Subject: Re: FreeBSD-HEAD gets stuck on vnode operations Message-ID: <5192618D.8070501@citrix.com> In-Reply-To: <20130513150018.GL3047@kib.kiev.ua> References: <5190CBEC.5000704@citrix.com> <5190F9A0.3000005@citrix.com> <20130513150018.GL3047@kib.kiev.ua>
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On 13/05/13 17:00, Konstantin Belousov wrote: > On Mon, May 13, 2013 at 04:33:04PM +0200, Roger Pau Monn? wrote: >> On 13/05/13 13:18, Roger Pau Monn? wrote: Thanks for taking a look, >> I would like to explain this a little bit more, the syncer process >> doesn't get blocked on the _mtx_trylock_flags_ call, it just continues >> looping forever in what seems to be an endless loop around >> mnt_vnode_next_active/ffs_sync. Also while in this state there is no >> noticeable disk activity, so I'm unsure of what is happening. > How many CPUs does your VM have ? 7 vCPUs, but I've also seen this issue with 4 and 16 vCPUs. > > The loop you describing means that other thread owns the vnode > interlock. Can you track what this thread does ? E.g. look at the > vp->v_interlock.mtx_lock, which is basically a pointer to the struct > thread owning the mutex, clear low bits as needed. Then you can > inspect the thread and get a backtrace. There are no other threads running, only syncer is running on CPU 1 (see ps in previous email). All other CPUs are idle, and as seen from the ps quite a lot of threads are blocked in vnode related operations, either "*Name Cac", "*vnode_fr" or "*vnode in". I've also attached the output of alllocks in the previous email. > > Does the loop you described stuck on the same vnode during the whole > lock-step time, or is the progress made, possibly slowly ? I'm not sure how to measure "progress", but indeed the syncer process is not locked, it is iterating over mnt_vnode_next_active. > > I suppose that your HEAD is recent. Last commit in my local repository is: Date: Tue, 7 May 2013 12:39:14 +0000 Subject: [PATCH] By request, add an arrow from NetBSD-0.8 to FreeBSD-1.0. While here, add a few more NetBSD versions to the tree itself. Submitted by: Alan Barrett <apb@cequrux.com> Submitted by: Thomas Klausner <wiz@netbsd.org>
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