Date: Fri, 15 Jan 2010 10:03:26 -0800 From: Pyun YongHyeon <pyunyh@gmail.com> To: Igor Sysoev <is@rambler-co.ru> Cc: freebsd-net@freebsd.org Subject: Re: hw.bge.forced_collapse Message-ID: <20100115180326.GF1228@michelle.cdnetworks.com> In-Reply-To: <20100115124942.GN84494@rambler-co.ru> References: <20091204075440.GH14822@rambler-co.ru> <20091204173243.GC16491@michelle.cdnetworks.com> <20091204191114.GB76992@rambler-co.ru> <20091204195140.GH16491@michelle.cdnetworks.com> <20091204201303.GD76992@rambler-co.ru> <20091204202213.GI16491@michelle.cdnetworks.com> <20100114160333.GC16657@rambler-co.ru> <20100114181031.GX1228@michelle.cdnetworks.com> <20100115124942.GN84494@rambler-co.ru>
next in thread | previous in thread | raw e-mail | index | archive | help
On Fri, Jan 15, 2010 at 03:49:42PM +0300, Igor Sysoev wrote: > On Thu, Jan 14, 2010 at 10:10:31AM -0800, Pyun YongHyeon wrote: > > > On Thu, Jan 14, 2010 at 07:03:33PM +0300, Igor Sysoev wrote: > > > On Fri, Dec 04, 2009 at 12:22:13PM -0800, Pyun YongHyeon wrote: > > > > > > > On Fri, Dec 04, 2009 at 11:13:03PM +0300, Igor Sysoev wrote: > > > > > On Fri, Dec 04, 2009 at 11:51:40AM -0800, Pyun YongHyeon wrote: > > > > > > > > > > > On Fri, Dec 04, 2009 at 10:11:14PM +0300, Igor Sysoev wrote: > > > > > > > On Fri, Dec 04, 2009 at 09:32:43AM -0800, Pyun YongHyeon wrote: > > > > > > > > > > > > > > > On Fri, Dec 04, 2009 at 10:54:40AM +0300, Igor Sysoev wrote: > > > > > > > > > I saw commit introducing hw.bge.forced_collapse loader tunable. > > > > > > > > > Just intresting, why it can not be a sysctl ? > > > > > > > > > > > > > > > > I didn't think the sysctl variable would be frequently changed > > > > > > > > in runtime except debugging driver so I took simple path. > > > > > > > > > > > > > > I do not think it's worth to reboot server just to look how various > > > > > > > values affect on bandwidth and CPU usage, expecially in production. > > > > > > > > > > > > > > As I understand the change is trivial: > > > > > > > > > > > > > > - CTLFLAG_RD > > > > > > > + CTLFLAG_RW > > > > > > > > > > > > > > since bge_forced_collapse is used atomically. > > > > > > > > > > > > > > > > > > > I have no problem changing it to RW but that case I may have to > > > > > > create actual sysctl node(e.g. dev.bge.0.forced_collapse) instead > > > > > > of hw.bge.forced_collapse which may affect all bge(4) controllers > > > > > > on system. Attached patch may be what you want. You can change the > > > > > > value at any time. > > > > > > > > > > Thank you for the patch. Can it be installed on 8-STABLE ? > > > > > > > > > > > > > bge(4) in HEAD has many fixes which were not MFCed to stable/8 so > > > > I'm not sure that patch could be applied cleanly. But I guess you > > > > can manually patch it. > > > > I'll wait a couple of days for wider testing/review and commit the > > > > patch. > > > > > > Sorry for the late response. We've tested bge.forced_collapse in December > > > on HEAD and found that values >1 froze connections with big data amount, > > > for example, "top -Ss1" output. Connection with small data amount such as > > > short ssh commands worked OK. Now I've tested modern 7.2-STABLE and found > > > that forced_collapse >1 freezes it too. > > > > > > > Thanks for reporting! It seems I've incorrectly dropped mbuf chains > > when collapsing fails. Would you try attached patch? > > BTW, it's strange that collapsing fails too often. > I think that comes from m_collapse(9) behavior. m_collapse(9) does not want to modify mbuf header pointer of the chain so it has more chance to fail than m_defrag(9) when the number of requested fragment is very low. m_defrag(9) always creates new mbuf so it may have more success rates if you have enough resources.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20100115180326.GF1228>