From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: [Ksummit-2005-discuss] Summary of 2005 Kernel Summit Proposed Topics Date: Tue, 29 Mar 2005 21:12:31 -0800 Message-ID: <424A353F.20903@zytor.com> References: <424346FE.20704@cs.wisc.edu> <20050324233921.GZ14202@opteron.random> <20050325034341.GV32638@waste.org> <20050327035149.GD4053@g5.random> <20050327054831.GA15453@waste.org> <1111905181.4753.15.camel@mylaptop> <20050326224621.61f6d917.davem@davemloft.net> <1112027284.5531.27.camel@mulgrave> <20050329152008.GD63268@muc.de> <1112116762.5088.65.camel@beastie> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Andi Kleen , James Bottomley , Rik van Riel , mpm@selenic.com, andrea@suse.de, michaelc@cs.wisc.edu, open-iscsi@googlegroups.com, ksummit-2005-discuss@thunk.org, netdev@oss.sgi.com Return-path: To: Dmitry Yusupov In-Reply-To: <1112116762.5088.65.camel@beastie> Sender: netdev-bounce@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org Dmitry Yusupov wrote: > On Tue, 2005-03-29 at 17:20 +0200, Andi Kleen wrote: > >>>In your scenario, if we're out of memory and the system needs several >>>ACK's to the swap device for pages to be released to the system, I don't >>>see how we make forward progress since without a reserved resource to >>>allocate from how does the ack make it up the stack to the storage >>>driver layer? >> >>Typically because the RX ring of the driver has some packets left. > > > You can not be sure. Some NICs has very small number for possible HW > ring buffers. Under OOM pressure, most likely, host will be so slow that > resources might not just be returned back to the HW in time. Though it > depends on link-layer driver implementation. > This seems to become part of the whole thing... in other words, in an OOM situation, may have to free RX ring entries by just dropping packets as necessary... -hpa