From e2adbcb480992de8a01acf9218e8bbd9b507fc6f Mon Sep 17 00:00:00 2001 From: Santiago Leon Date: Wed, 26 Oct 2005 10:47:08 -0600 Subject: [PATCH] [PATCH] ibmveth fix buffer replenishing This patch removes the allocation of RX skb's buffers from a workqueue to be called directly at RX processing time. This change was suggested by Dave Miller when the driver was starving the RX buffers and deadlocking under heavy traffic: > Allocating RX SKBs via tasklet is, IMHO, the worst way to > do it. It is no surprise that there are starvation cases. > > If tasklets or work queues get delayed in any way, you lose, > and it's very easy for a card to catch up with the driver RX'ing > packets very fast, no matter how aggressive you make the > replenishing. By the time you detect that you need to be > "more aggressive" it is already too late. > The only pseudo-reliable way is to allocate at RX processing time. > Signed-off-by: Santiago Leon Signed-off-by: Jeff Garzik --- drivers/net/ibmveth.c | 48 ++++++++----------------------------------- drivers/net/ibmveth.h | 4 ---- 2 files changed, 8 insertions(+), 44 deletions(-) diff --git a/drivers/net/ibmveth.c b/drivers/net/ibmveth.c index d985b804a762..aea1598b2253 100644 --- a/drivers/net/ibmveth.c +++ b/drivers/net/ibmveth.c @@ -96,7 +96,6 @@ static void ibmveth_proc_unregister_driver(void); static void ibmveth_proc_register_adapter(struct ibmveth_adapter *adapter); static void ibmveth_proc_unregister_adapter(struct ibmveth_adapter *adapter); static irqreturn_t ibmveth_interrupt(int irq, void *dev_instance, struct pt_regs *regs); -static inline void ibmveth_schedule_replenishing(struct ibmveth_adapter*); static inline void ibmveth_rxq_harvest_buffer(struct ibmveth_adapter *adapter); #ifdef CONFIG_PROC_FS @@ -257,29 +256,7 @@ static void ibmveth_replenish_buffer_pool(struct ibmveth_adapter *adapter, struc atomic_add(buffers_added, &(pool->available)); } -/* check if replenishing is needed. */ -static inline int ibmveth_is_replenishing_needed(struct ibmveth_adapter *adapter) -{ - int i; - - for(i = 0; i < IbmVethNumBufferPools; i++) - if(adapter->rx_buff_pool[i].active && - (atomic_read(&adapter->rx_buff_pool[i].available) < - adapter->rx_buff_pool[i].threshold)) - return 1; - return 0; -} - -/* kick the replenish tasklet if we need replenishing and it isn't already running */ -static inline void ibmveth_schedule_replenishing(struct ibmveth_adapter *adapter) -{ - if(ibmveth_is_replenishing_needed(adapter) && - (atomic_dec_if_positive(&adapter->not_replenishing) == 0)) { - schedule_work(&adapter->replenish_task); - } -} - -/* replenish tasklet routine */ +/* replenish routine */ static void ibmveth_replenish_task(struct ibmveth_adapter *adapter) { int i; @@ -292,10 +269,6 @@ static void ibmveth_replenish_task(struct ibmveth_adapter *adapter) &adapter->rx_buff_pool[i]); adapter->rx_no_buffer = *(u64*)(((char*)adapter->buffer_list_addr) + 4096 - 8); - - atomic_inc(&adapter->not_replenishing); - - ibmveth_schedule_replenishing(adapter); } /* empty and free ana buffer pool - also used to do cleanup in error paths */ @@ -563,10 +536,10 @@ static int ibmveth_open(struct net_device *netdev) return rc; } - netif_start_queue(netdev); + ibmveth_debug_printk("initial replenish cycle\n"); + ibmveth_replenish_task(adapter); - ibmveth_debug_printk("scheduling initial replenish cycle\n"); - ibmveth_schedule_replenishing(adapter); + netif_start_queue(netdev); ibmveth_debug_printk("open complete\n"); @@ -584,9 +557,6 @@ static int ibmveth_close(struct net_device *netdev) free_irq(netdev->irq, netdev); - cancel_delayed_work(&adapter->replenish_task); - flush_scheduled_work(); - do { lpar_rc = h_free_logical_lan(adapter->vdev->unit_address); } while (H_isLongBusy(lpar_rc) || (lpar_rc == H_Busy)); @@ -795,7 +765,7 @@ static int ibmveth_poll(struct net_device *netdev, int *budget) } } while(more_work && (frames_processed < max_frames_to_process)); - ibmveth_schedule_replenishing(adapter); + ibmveth_replenish_task(adapter); if(more_work) { /* more work to do - return that we are not done yet */ @@ -931,8 +901,10 @@ static int ibmveth_change_mtu(struct net_device *dev, int new_mtu) } + /* kick the interrupt handler so that the new buffer pools get + replenished or deallocated */ + ibmveth_interrupt(dev->irq, dev, NULL); - ibmveth_schedule_replenishing(adapter); dev->mtu = new_mtu; return 0; } @@ -1017,14 +989,10 @@ static int __devinit ibmveth_probe(struct vio_dev *dev, const struct vio_device_ ibmveth_debug_printk("adapter @ 0x%p\n", adapter); - INIT_WORK(&adapter->replenish_task, (void*)ibmveth_replenish_task, (void*)adapter); - adapter->buffer_list_dma = DMA_ERROR_CODE; adapter->filter_list_dma = DMA_ERROR_CODE; adapter->rx_queue.queue_dma = DMA_ERROR_CODE; - atomic_set(&adapter->not_replenishing, 1); - ibmveth_debug_printk("registering netdev...\n"); rc = register_netdev(netdev); diff --git a/drivers/net/ibmveth.h b/drivers/net/ibmveth.h index a5d27a9cdf1f..a3ea02937d63 100644 --- a/drivers/net/ibmveth.h +++ b/drivers/net/ibmveth.h @@ -118,10 +118,6 @@ struct ibmveth_adapter { dma_addr_t filter_list_dma; struct ibmveth_buff_pool rx_buff_pool[IbmVethNumBufferPools]; struct ibmveth_rx_q rx_queue; - atomic_t not_replenishing; - - /* helper tasks */ - struct work_struct replenish_task; /* adapter specific stats */ u64 replenish_task_cycles; -- 2.20.1