Date: Tue, 5 Feb 2008 17:17:39 +0300 From: Gleb Smirnoff <glebius@FreeBSD.org> To: Louis Mamakos <louie@transsys.com> Cc: cvs-src@FreeBSD.org, Alexander Motin <mav@FreeBSD.org>, src-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/netgraph/netflow ng_netflow.c Message-ID: <20080205141739.GX14339@FreeBSD.org> In-Reply-To: <C0C34BEB-3EB8-4552-B0BD-CE481311C77A@transsys.com> References: <200801271501.m0RF1Hki089075@repoman.freebsd.org> <20080202201153.GL14339@FreeBSD.org> <47A4E122.8080901@FreeBSD.org> <C0C34BEB-3EB8-4552-B0BD-CE481311C77A@transsys.com>
next in thread | previous in thread | raw e-mail | index | archive | help
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> > 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. GLEBIUS-RIPN GLEB-RIPE
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20080205141739.GX14339>