From: Neil Turton Date: Sat, 13 Dec 2008 05:41:06 +0000 (-0800) Subject: sfc: Add option to use a separate channel for TX completions X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=28b581ab0a0aa7bc8b22935779ca3e8d6f651ac7;p=linux-beck.git sfc: Add option to use a separate channel for TX completions In a bidirectional forwarding test, we find that the best performance is achieved by sending the TX completion interrupts from one NIC to a CPU which shares an L2 cache with RX completion interrupts from the other NIC. To facilitate this, add an option (through a module parameter) to create separate channels for RX and TX completion with separate IRQs when MSI-X is available. Signed-off-by: Ben Hutchings Signed-off-by: David S. Miller --- diff --git a/drivers/net/sfc/efx.c b/drivers/net/sfc/efx.c index 15ae2fcf6416..2faaa965afca 100644 --- a/drivers/net/sfc/efx.c +++ b/drivers/net/sfc/efx.c @@ -64,13 +64,15 @@ MODULE_PARM_DESC(lro, "Large receive offload acceleration"); /* * Use separate channels for TX and RX events * - * Set this to 1 to use separate channels for TX and RX. It allows us to - * apply a higher level of interrupt moderation to TX events. + * Set this to 1 to use separate channels for TX and RX. It allows us + * to control interrupt affinity separately for TX and RX. * - * This is forced to 0 for MSI interrupt mode as the interrupt vector - * is not written + * This is only used in MSI-X interrupt mode */ -static unsigned int separate_tx_and_rx_channels = true; +static unsigned int separate_tx_channels; +module_param(separate_tx_channels, uint, 0644); +MODULE_PARM_DESC(separate_tx_channels, + "Use separate channels for TX and RX"); /* This is the weight assigned to each of the (per-channel) virtual * NAPI devices. @@ -846,26 +848,33 @@ static void efx_probe_interrupts(struct efx_nic *efx) if (efx->interrupt_mode == EFX_INT_MODE_MSIX) { struct msix_entry xentries[EFX_MAX_CHANNELS]; int wanted_ints; + int rx_queues; /* We want one RX queue and interrupt per CPU package * (or as specified by the rss_cpus module parameter). * We will need one channel per interrupt. */ - wanted_ints = rss_cpus ? rss_cpus : efx_wanted_rx_queues(); - efx->n_rx_queues = min(wanted_ints, max_channels); + rx_queues = rss_cpus ? rss_cpus : efx_wanted_rx_queues(); + wanted_ints = rx_queues + (separate_tx_channels ? 1 : 0); + wanted_ints = min(wanted_ints, max_channels); - for (i = 0; i < efx->n_rx_queues; i++) + for (i = 0; i < wanted_ints; i++) xentries[i].entry = i; - rc = pci_enable_msix(efx->pci_dev, xentries, efx->n_rx_queues); + rc = pci_enable_msix(efx->pci_dev, xentries, wanted_ints); if (rc > 0) { - EFX_BUG_ON_PARANOID(rc >= efx->n_rx_queues); - efx->n_rx_queues = rc; + EFX_ERR(efx, "WARNING: Insufficient MSI-X vectors" + " available (%d < %d).\n", rc, wanted_ints); + EFX_ERR(efx, "WARNING: Performance may be reduced.\n"); + EFX_BUG_ON_PARANOID(rc >= wanted_ints); + wanted_ints = rc; rc = pci_enable_msix(efx->pci_dev, xentries, - efx->n_rx_queues); + wanted_ints); } if (rc == 0) { - for (i = 0; i < efx->n_rx_queues; i++) + efx->n_rx_queues = min(rx_queues, wanted_ints); + efx->n_channels = wanted_ints; + for (i = 0; i < wanted_ints; i++) efx->channel[i].irq = xentries[i].vector; } else { /* Fall back to single channel MSI */ @@ -877,6 +886,7 @@ static void efx_probe_interrupts(struct efx_nic *efx) /* Try single interrupt MSI */ if (efx->interrupt_mode == EFX_INT_MODE_MSI) { efx->n_rx_queues = 1; + efx->n_channels = 1; rc = pci_enable_msi(efx->pci_dev); if (rc == 0) { efx->channel[0].irq = efx->pci_dev->irq; @@ -889,6 +899,7 @@ static void efx_probe_interrupts(struct efx_nic *efx) /* Assume legacy interrupts */ if (efx->interrupt_mode == EFX_INT_MODE_LEGACY) { efx->n_rx_queues = 1; + efx->n_channels = 1 + (separate_tx_channels ? 1 : 0); efx->legacy_irq = efx->pci_dev->irq; } } @@ -913,8 +924,8 @@ static void efx_set_channels(struct efx_nic *efx) struct efx_rx_queue *rx_queue; efx_for_each_tx_queue(tx_queue, efx) { - if (!EFX_INT_MODE_USE_MSI(efx) && separate_tx_and_rx_channels) - tx_queue->channel = &efx->channel[1]; + if (separate_tx_channels) + tx_queue->channel = &efx->channel[efx->n_channels-1]; else tx_queue->channel = &efx->channel[0]; tx_queue->channel->used_flags |= EFX_USED_BY_TX; diff --git a/drivers/net/sfc/net_driver.h b/drivers/net/sfc/net_driver.h index f91060963475..2c5b5fabac1e 100644 --- a/drivers/net/sfc/net_driver.h +++ b/drivers/net/sfc/net_driver.h @@ -649,6 +649,7 @@ union efx_multicast_hash { * @rx_queue: RX DMA queues * @channel: Channels * @n_rx_queues: Number of RX queues + * @n_channels: Number of channels in use * @rx_buffer_len: RX buffer length * @rx_buffer_order: Order (log2) of number of pages for each RX buffer * @irq_status: Interrupt status buffer @@ -728,6 +729,7 @@ struct efx_nic { struct efx_channel channel[EFX_MAX_CHANNELS]; int n_rx_queues; + int n_channels; unsigned int rx_buffer_len; unsigned int rx_buffer_order;