Date: Wed, 22 Sep 2010 15:21:53 +0200 From: Attila Nagy <bra@fsn.hu> To: freebsd-fs@FreeBSD.org Subject: Re: zcolli (zcollide) state, what does znode dying means? Message-ID: <4C9A02F1.6020604@fsn.hu> In-Reply-To: <4C99DC90.70208@fsn.hu> References: <4C99DC90.70208@fsn.hu>
next in thread | previous in thread | raw e-mail | index | archive | help
On 09/22/10 12:38, Attila Nagy wrote: > I have a machine, which is heavily hammered with file system > operations, running a very recent 8-STABLE. > The symptom is that everything works fine for a few minutes, then a > lot of processes get into zcolli state (according to top). At that > there there are two outcomes: > 1. the disks calm down for a while (for long seconds, there is no, or > very small amount of IO, verified with gstat), top shows nearly 100% > system, a lot of processes are on the run queue (load is in the sky, > around 300 and 1000), all operations stop, top refreshes, but I can't > really execute new programs, then suddenly the zcolli states change > and the IO resumes and the run queue decreases. > 2. the system remains in this state, after 5-10 minutes there is still > no change, only a reset helps (doesn't even react to CTRL-ALT-DEL, but > running programs, like top still refreshes, but no disk IO can be made) It turned out that due to a restart prefetch got enabled. On this machine it made so much extra IO (it does mostly random reads) that it could livelock itself. The only thing I don't understand is why the IO ceased during the mass zcollide period, that seems to be a wait for something scenario (sometimes endlessly), which is bad.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4C9A02F1.6020604>