zfs, mc, mcview and files opening

[Marko Turk]

Hi,

On Tue, Nov 10, 2015 at 02:58:32PM +0500, Eugene M. Zheganin wrote:
> Hi.
> 
> my midnight commander is terribly slow at vieweing files with mcview.
> Opening of a file of approximately 10 megabytes takes about 30-40
> seconds. This isn't related with the compression setting, %busy wait or
> pool properties- I tested on various machines, it's fully reproducible.
> This lag appears on files about 1.5 megs in size, and the lag time is
> pretty constant.  From my observation, it's the following syscall that's
> blocking:
> 
> fstat(4,{ mode=p--------- ,inode=41,size=0,blksize=4096 }) = 0 (0x0)
> (observed using `truss mcview maillog`)
> 
> If the file is viewed not by mcview (i.e. it is of a special type and
> viewed by the special utility, or mcview is simply not used - for
> example more opens same file without lag) - the file is opening fast as
> always. When mcview is involved - lag appears. In the same time I've
> never seen this lag on filesystems other than zfs.

Is this happening on every ZFS FreeBSD install or just some of them? I'm
running ZFS on FreeBSD 10-STABLE and I don't see this problem (even for
much larger files).

BR,
Marko

> And the most
> beautiful detail is that this lag is repeatable on multiple opens of
> same file - though you can expect that it will be only first time that
> would be that slow, it doesn't happen - same pause occurs on sequential
> opens.
> 
> Who's issue is this ?
> Can some workaround be used ?
> 
> Thanks.
> Eugene.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 819 bytes
Desc: not available
URL: <http://lists.freebsd.org/pipermail/freebsd-stable/attachments/20151110/a11e377b/attachment.bin>