cvs commit: src/sys/netgraph/netflow ng_netflow.c
glebius at FreeBSD.org
Tue Feb 5 06:17:37 PST 2008
On Sun, Feb 03, 2008 at 11:36:49AM -0500, Louis Mamakos wrote:
L> > Gleb Smirnoff пишет:
L> >> you should have asked me for review before committing! This is
L> >> not a bug, this is a feature. This was quite clear from the comments,
L> >> that you removed:
L> >> - /* if export hook disconnected stop running expire(). */
L> >> This is intended behavior. We must not lose information unless
L> >> user explicitly wants to lose information. In the latter case
L> >> he will connect ng_hole(4) node to the "export" hook. But we must
L> >> not lose information if user runs some script that swaps receiving
L> >> node on the "export" hook.
L> >> Please backout this change!
L> > Expire process was not depending completely on connected hook even before
L> > this commit. For example, every TCP session closing forces some data
L> > export. So even with export hook disconnected some data still will be lost
L> > and not just lost, but it was leading to memory leak which I have fixed
L> > with other commit.
That's true. The active TCP close should be reworked. And the new active expiry
feature violates the original design, when no export hook ment, no data lose. :(
L> If there's a concern about no losing the netflow data, then it's likely that
L> it's usually the case that an export hook is connected. If a user wanted to
L> change the export arrangement for the netflow data, then just disconnected
L> and reconnecting to the export hook won't caused data to be lost if the
L> expiry parameters are set to something reasonable.
Since expiry runs periodically, then it can race with hook change
L> Finally, in the absence of infinite amounts of memory, data will eventually
L> be lost. The only decision is over what duration data should be kept around
L> so that it might be harvested. It's a huge surprise that the netflow module
L> consumes large amounts of kernel memory. As a user, I expected the
L> expiration timers to be the policy that I specify to control how long the
L> netflow stats are stored, and my expectation wasn't met.
Huge surprise? How can you expect a kernel module that stores a lot of data
consume a little kernel memory?
I agree that the behavior should be documented in manual page and using
ng_hole(4) for your case should be advised. If you send me a manual page patch,
I can commit it.
Totus tuus, Glebius.
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