Re: ZFS leaking vnodes (sort of)

That looks more like bad disk than a file system bug.




On 7/11/07, Simon Dircks <enderbsd_at_gmail.com> wrote:
> On 7/9/07, Huang wen hui <huang_at_gddsn.org.cn> wrote:
> >
> > Pawel Jakub Dawidek $B<LF;(B:
> > > On Sat, Jul 07, 2007 at 02:26:17PM +0100, Doug Rabson wrote:
> > >
> > >> I've been testing ZFS recently and I noticed some performance issues
> > >> while doing large-scale port builds on a ZFS mounted /usr/ports tree.
> > >> Eventually I realised that virtually nothing ever ended up on the vnode
> > >> free list. This meant that when the system reached its maximum vnode
> > >> limit, it had to resort to reclaiming vnodes from the various
> > >> filesystem's active vnode lists (via vlrureclaim). Since those lists
> > >> are not sorted in LRU order, this led to pessimal cache performance
> > >> after the system got into that state.
> > >>
> > >> I looked a bit closer at the ZFS code and poked around with DDB and I
> > >> think the problem was caused by a couple of extraneous calls to vhold
> > >> when creating a new ZFS vnode. On FreeBSD, getnewvnode returns a vnode
> > >> which is already held (not on the free list) so there is no need to
> > >> call vhold again.
> > >>
> > >
> > > Whoa! Nice catch... The patch works here - I did some pretty heavy
> > > tests, so please commit it ASAP.
> > >
> > > I also wonder if this can help with some of those 'kmem_map too small'
> > > panics. I was observing that ARC cannot reclaim memory and this may be
> > > because all vnodes and thus associated data are beeing held.
> > >
> > > To ZFS users having problems with performance and/or stability of ZFS:
> > > Can you test the patch and see if it helps?
> > >
> > my T60p notebook, -CURRENT amd64:
> > buildworld time before patch: 58xx second.
> > buildworld time after path: 28xx second.
> >
> > Thanks!
>
>
>
> With this patch i am still able to reproduce my ZFS crash.
>
> controllera# uname -a
> FreeBSD controllera.storage.ksdhost.com 7.0-CURRENT FreeBSD 7.0-CURRENT #0:
> Thu Jul 12 02:28:52 UTC 2007
> graff_at_controllera.storage.ksdhost.com:/usr/obj/usr/src/sys/CONTROLLERA
> amd64
>
>
> panic: ZFS: bad checksum (read on <unknown> off 0: zio 0xffffff001d729810
> [LO SP
> A space map] 1000L/800P DVA[0]=<0:1600421800:800> DVA[1]=<0:2c000f7000:800>
> DVA[
> 2]=<0:4200013800:800> fletcher4 lzjb LE contiguous birth=566 fill=1
> chsum=5d3276
> 7b98:635ff7022f8b:4251
> cpuid = 0
> KDB: enter: panic
> [thread pid 802 tid 100066 ]
> stopped at kdb_enter+0x31: leave
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