Hmm looks like you might be running into the tcp fusion flow control limitations mentioned in infodoc 203612..
http://sunsolve.sun.com/search/document.do?assetkey=1-61-203612-1&searchclause= 203612 See also the following bugids, 6633302 and 6563902. http://sunsolve.sun.com/search/document.do?assetkey=1-1-6633302-1 http://sunsolve.sun.com/search/document.do?assetkey=1-1-6563902-1 -George *>Date: Tue, 18 Mar 2008 06:28:27 -0400 *>From: James Carlson <[EMAIL PROTECTED]> *>Subject: Re: [networking-discuss] Loopback - increasing MTU size *>To: "Chih - Wei Yu [ MTN - Innovation Centre ]" <[EMAIL PROTECTED]> *>Cc: [email protected], [EMAIL PROTECTED] *>MIME-version: 1.0 *>Content-transfer-encoding: 7BIT *>X-BeenThere: [email protected] *>Delivered-to: [email protected] *>X-PMX-Version: 5.4.1.325704 *>X-Spam-Checker-Version: SpamAssassin 3.2.3 (2007-08-08) on oss-mail1.opensolaris.org *>X-Original-To: [email protected] *>X-Antispam: No, score=-2.6/5.0, scanned in 0.078sec at (localhost [127.0.0.1]) by smf-spamd v1.3.1 - http://smfs.sf.net/ *>X-Mailman-Version: 2.1.9 *>List-Post: <mailto:[email protected]> *>List-Subscribe: <http://mail.opensolaris.org/mailman/listinfo/networking-discuss>, <mailto:[EMAIL PROTECTED]> *>List-Unsubscribe: <http://mail.opensolaris.org/mailman/listinfo/networking-discuss>, <mailto:[EMAIL PROTECTED]> *>List-Archive: <http://mail.opensolaris.org/pipermail/networking-discuss> *>List-Help: <mailto:[EMAIL PROTECTED]> *>List-Id: Networking General Discussion <networking-discuss.opensolaris.org> *>X-Spam-Status: No, score=-1.0 required=5.0 tests=AWL,RCVD_IN_DNSWL_LOW autolearn=unavailable version=3.2.3 *>X-Spam-Level: *> *>Chih - Wei Yu [ MTN - Innovation Centre ] writes: *>> > but i get error indicating invalid arguments. *>> *>> $$$Correct; the system doesn't allow you to do that. It won't let you *>> set the MTU $$$greater than ill_max_frag, which is hard-coded to *>> IP_LOOPBACK_MTU (8192) for lo0. *>> *>> >>>>>>>>So there's no way to increase it higher. *> *>Correct. *> *>> $$$How have you determined that the default MTU setting on the lo0 *>> interface is in $$$fact the problem in this instance? *>> *>> >>>>Well, it's a hunch. I increased receive and buffer sizes on both *>> ends and try to push the rate higher. After a couple of minutes, the TCP *>> connection gets blocked and one of the ends get block in sending state. *>> Doing a netstat on the loopback, I can see that there are packets *>> initially but then once its gets blocked, there are no packets between *>> both ends. Even when I increased the rate, I see roughly the same size *>> of bytes being relayed between both ends (netstat -I lo0 1, roughly *>> 8800~9000 packets every second). *> *>It sounds to me like you've run into a bug of some sort, not a tuning *>issue. The system shouldn't need to be tuned for local traffic *>... or, really, any traffic. *> *>I suggest that you work with Sun's support group to find and fix the *>root cause of the problem you're seeing. *> *>> >>>>>On Linux, I was able to set the MTU value on the loopback much *>> higher but then again, I didn't run the test through the Linux machine. *> *>I don't think that modifying the loopback MTU is the right approach *>here. *> *>It's important to understand that when you're using loopback traffic, *>the system connects the endpoints directly together. The "MTU" has *>little to do with how it works and shouldn't be harming performance. *> *>-- *>James Carlson, Solaris Networking <[EMAIL PROTECTED]> *>Sun Microsystems / 35 Network Drive 71.232W Vox +1 781 442 2084 *>MS UBUR02-212 / Burlington MA 01803-2757 42.496N Fax +1 781 442 1677 *>_______________________________________________ *>networking-discuss mailing list *>[email protected] George Shepherd http://clem.uk/~georges/ ============================================================================== Solaris Revenue Product Engineering: | SUN Microsystems Core team -Internet | Guillemont Park Email: [EMAIL PROTECTED] | Camberley GU17 9QG Disclaimer: Less is more, more or less | United Kingdom ============================================================================== _______________________________________________ networking-discuss mailing list [email protected]
