Date: Sat, 29 Jul 2006 16:01:39 +0900 From: Pyun YongHyeon <pyunyh@gmail.com> To: freebsd-current@FreeBSD.org Subject: em(4) patch for ENOBUFS Message-ID: <20060729070139.GB27724@cdnetworks.co.kr>
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Hi, Whilst reading em(4) code to fix jb's sun4v issue I noticed em(4) is very vulnerable to ENOBUFS situation on receive path. If em(4) encounter an ENOBUFS it just breaks receive loop and then try to process the packet next time. However it didn't update the Rx descriptor status so it never process receive path again(em_handle_rxtx task runs but it couldn't complete its job and the task takes up all your CPU). I've revised receive path to cope with the ENOBUFS situation more gracefully. It also contains a fix to handle DMA map loading failure case on receive path by allocating a spare DMA map. If you have em(4) and experienced ENOBUFS problem please try the following patch and let me know the result. http://people.freebsd.org/~yongari/em.ENOBUFS.patch You can reproduce current issue by lowering number of mbuf clusters in /boot/loader.conf. For example, add kern.ipc.nmbclusters="1000" to limit number of mbuf clusters. -- Regards, Pyun YongHyeon
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