The uio_yield() idea did not work. Still have the same 31 second
interval
packet loss.
Is it safe to assume the vp will be valid after a msleep() or
uio_yield()? If
so can we do something a little different:
Currently:
/* this takes too long when list is large */
MNT_VNODE_FOREACH(vp, mp, mvp) {
do work
}
Why not do this incrementally and call ffs_sync() more often, or
break it out into ffs_isync() (incremental sync).
static struct vnode *vp;
/* first? */
if (!vp)
vp = __mnt_vnode_first(&mvp, mp);
for (vcount = 0; vp && (vcount != 500); ++vcount) {
do work
vp = __mnt_vnode_next(&mvp, mp);
}
The problem I see with this is a race condition where this list may
change
between the incremental calls.
--
mark
On Dec 21, 2007, at 6:43 PM, David G Lawrence wrote:
Unfortunately, the version of the patch that I sent out isn't
going to
help your problem. It needs to yield at the top of the loop, but
vp isn't
necessarily valid after the wakeup from the msleep. That's a
problem that
I'm having trouble figuring out a solution to - the solutions
that come
to mind will all significantly increase the overhead of the loop.
I apologize for not reading the code as I am swamped, but a technique
that Matt Dillon used for bufs might work here.
Can you use a placeholder vnode as a place to restart the scan?
you might have to mark it special so that other threads/things
(getnewvnode()?) don't molest it, but it can provide for a convenient
restart point.
That was one of the solutions that I considered and rejected
since it
would significantly increase the overhead of the loop.
The solution provided by Kostik Belousov that uses uio_yield
looks like
a find solution. I intend to try it out on some servers RSN.
-DG
David G. Lawrence
President
Download Technologies, Inc. - http://www.downloadtech.com - (866)
399 8500
The FreeBSD Project - http://www.freebsd.org
Pave the road of life with opportunities.
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