Date: Tue, 8 Jan 2013 08:42:44 -0800 From: Tim Gustafson <tjg@soe.ucsc.edu> To: Andrey Simonenko <simon@comsys.ntu-kpi.kiev.ua> Cc: FreeBSD Filesystems <freebsd-fs@freebsd.org> Subject: Re: Problems Re-Starting mountd Message-ID: <CAG27QgTF8HbcmwOzMHUL1eEBpS57unD5=V2bpRWYraP1T%2BBemA@mail.gmail.com> In-Reply-To: <20130108150508.GA2248@pm513-1.comsys.ntu-kpi.kiev.ua> References: <CAG27QgRi89jHWeqzuNikpGM7=JiV%2BDB8f5Xu0JYGhEfQwOrjKQ@mail.gmail.com> <20130103123730.GA19137@pm513-1.comsys.ntu-kpi.kiev.ua> <CAG27QgTuGyPSVxTbCnP3U494ftPxzX5HD56Mtkc-2jMFPNk=ZQ@mail.gmail.com> <20130108150508.GA2248@pm513-1.comsys.ntu-kpi.kiev.ua>
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> As I understood each /export/home/* pathname from /etc/exports is > a mount point for ZFS file system. Correct. > I created 2000 file systems on ZFS file system backed by vnode md(4) > device. The /etc/exports file contains 4000 entries like your example. > > On 9.1-STABLE mountd spends ~70 seconds in flushing current NFS exports > in the NFS server, parsing data from /etc/exports and loading parsed > data into the NFS server. ~70 seconds is not several minutes. Most of > time mountd spends in nmount() system call in "zio->io_cv" lock. I suspect that statfs(), nmount() and lstat() will return much more quickly for md-based file systems, since they have zero latency. > Can you show the output of "truss -fc -o /tmp/output.txt mountd" > (wait wchan "select" state of mountd and terminate it by a signal). > If everything is correct you should see N statfs() calls, N+M nmount() > calls and something*N lstat() calls, where N is the number of /etc/exports > lines, M is the number of mounted file systems. Number of lstat() calls > depends on number of components in pathnames. I will try to run this tonight; I can't do it now as people are already starting to work today. -- Tim Gustafson tjg@soe.ucsc.edu 831-459-5354 Baskin Engineering, Room 313A
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