Date: Mon, 13 Sep 2010 15:21:13 -0700 From: "David Christensen" <davidch@broadcom.com> To: "pyunyh@gmail.com" <pyunyh@gmail.com>, "Andre Oppermann" <andre@freebsd.org> Cc: Tom Judge <tom@tomjudge.com>, "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>, "yongari@freebsd.org" <yongari@freebsd.org> Subject: RE: bce(4) - com_no_buffers (Again) Message-ID: <5D267A3F22FD854F8F48B3D2B52381933B540B4C14@IRVEXCHCCR01.corp.ad.broadcom.com> In-Reply-To: <20100913193947.GH1229@michelle.cdnetworks.com> References: <4C894A76.5040200@tomjudge.com> <20100910002439.GO7203@michelle.cdnetworks.com> <4C8E3D79.6090102@tomjudge.com> <20100913184833.GF1229@michelle.cdnetworks.com> <4C8E775D.8070202@freebsd.org> <20100913193947.GH1229@michelle.cdnetworks.com>
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> I'm under the impression the header splitting in bce(4) is for > LRO(opposite of TSO), not for VM magic to enable page flipping > tricks. Header splitting was implemented in the Linux version of bce(4) to prevent jumbo memory allocations. Allocating 9KB frames was causing problems on systems used for virtualization. (Harder to find a contiguous 9KB frame when a hypervisor is in use.) Using=20 4KB or smaller buffer sizes was considered more compatible with virtualization. =20 LRO (Large Receive Offload, aka Transparent Packet Aggregation or TPA on the 10Gb controllers) is not supported on the 1Gb=20 bce(4) devices. Dave
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