diff options
| -rw-r--r-- | sys/dev/bge/if_bge.c | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/sys/dev/bge/if_bge.c b/sys/dev/bge/if_bge.c index 8ca0c73..b42d44f 100644 --- a/sys/dev/bge/if_bge.c +++ b/sys/dev/bge/if_bge.c @@ -483,12 +483,29 @@ DRIVER_MODULE(bge, pci, bge_driver, bge_devclass, 0, 0); DRIVER_MODULE(miibus, bge, miibus_driver, miibus_devclass, 0, 0); static int bge_allow_asf = 1; +/* + * A common design characteristic for many Broadcom client controllers + * is that they only support a single outstanding DMA read operation + * on the PCIe bus. This means that it will take twice as long to fetch + * a TX frame that is split into header and payload buffers as it does + * to fetch a single, contiguous TX frame (2 reads vs. 1 read). For + * these controllers, coalescing buffers to reduce the number of memory + * reads is effective way to get maximum performance(about 940Mbps). + * Without collapsing TX buffers the maximum TCP bulk transfer + * performance is about 850Mbps. However forcing coalescing mbufs + * consumes a lot of CPU cycles, so leave it off by default. + */ +static int bge_forced_collapse = 0; TUNABLE_INT("hw.bge.allow_asf", &bge_allow_asf); +TUNABLE_INT("hw.bge.forced_collapse", &bge_forced_collapse); SYSCTL_NODE(_hw, OID_AUTO, bge, CTLFLAG_RD, 0, "BGE driver parameters"); SYSCTL_INT(_hw_bge, OID_AUTO, allow_asf, CTLFLAG_RD, &bge_allow_asf, 0, "Allow ASF mode if available"); +SYSCTL_INT(_hw_bge, OID_AUTO, forced_collapse, CTLFLAG_RD, &bge_forced_collapse, + 0, "Number of fragmented TX buffers of a frame allowed before " + "forced collapsing"); #define SPARC64_BLADE_1500_MODEL "SUNW,Sun-Blade-1500" #define SPARC64_BLADE_1500_PATH_BGE "/pci@1f,700000/network@2" @@ -3915,6 +3932,26 @@ bge_encap(struct bge_softc *sc, struct mbuf **m_head, uint32_t *txidx) csum_flags |= BGE_TXBDFLAG_IP_FRAG; } + if ((m->m_pkthdr.csum_flags & CSUM_TSO) == 0 && + bge_forced_collapse > 0 && (sc->bge_flags & BGE_FLAG_PCIE) != 0 && + m->m_next != NULL) { + /* + * Forcedly collapse mbuf chains to overcome hardware + * limitation which only support a single outstanding + * DMA read operation. + */ + if (bge_forced_collapse == 1) + m = m_defrag(m, M_DONTWAIT); + else + m = m_collapse(m, M_DONTWAIT, bge_forced_collapse); + if (m == NULL) { + m_freem(*m_head); + *m_head = NULL; + return (ENOBUFS); + } + *m_head = m; + } + map = sc->bge_cdata.bge_tx_dmamap[idx]; error = bus_dmamap_load_mbuf_sg(sc->bge_cdata.bge_tx_mtag, map, m, segs, &nsegs, BUS_DMA_NOWAIT); |
