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Message-ID: <1363031977.2608.59.camel@bwh-desktop.uk.solarflarecom.com>
Date: Mon, 11 Mar 2013 19:59:37 +0000
From: Ben Hutchings <bhutchings@...arflare.com>
To: David Miller <davem@...emloft.net>
CC: <netdev@...r.kernel.org>, <linux-net-drivers@...arflare.com>,
<scrum-linux@...arflare.com>
Subject: [PATCH net-next 22/22] sfc: allocate more RX buffers per page
From: Daniel Pieczko <dpieczko@...arflare.com>
Allocating 2 buffers per page is insanely inefficient when MTU is 1500
and PAGE_SIZE is 64K (as it usually is on POWER). Allocate as many as
we can fit, and choose the refill batch size at run-time so that we
still always use a whole page at once.
[bwh: Fix loop condition to allow for compound pages; rebase]
Signed-off-by: Ben Hutchings <bhutchings@...arflare.com>
---
drivers/net/ethernet/sfc/efx.c | 18 +++++---
drivers/net/ethernet/sfc/efx.h | 1 +
drivers/net/ethernet/sfc/net_driver.h | 2 +
drivers/net/ethernet/sfc/rx.c | 80 +++++++++++++++++---------------
4 files changed, 56 insertions(+), 45 deletions(-)
diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index a70c458..f050248 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -643,10 +643,6 @@ static void efx_start_datapath(struct efx_nic *efx)
if (rx_buf_len <= PAGE_SIZE) {
efx->rx_scatter = false;
efx->rx_buffer_order = 0;
- if (rx_buf_len <= PAGE_SIZE / 2)
- efx->rx_buffer_truesize = PAGE_SIZE / 2;
- else
- efx->rx_buffer_truesize = PAGE_SIZE;
} else if (efx->type->can_rx_scatter) {
BUILD_BUG_ON(sizeof(struct efx_rx_page_state) +
EFX_PAGE_IP_ALIGN + EFX_RX_USR_BUF_SIZE >
@@ -654,14 +650,22 @@ static void efx_start_datapath(struct efx_nic *efx)
efx->rx_scatter = true;
efx->rx_dma_len = EFX_RX_USR_BUF_SIZE;
efx->rx_buffer_order = 0;
- efx->rx_buffer_truesize = PAGE_SIZE / 2;
} else {
efx->rx_scatter = false;
efx->rx_buffer_order = get_order(rx_buf_len);
- efx->rx_buffer_truesize = PAGE_SIZE << efx->rx_buffer_order;
}
- efx->rx_bufs_per_page = (rx_buf_len <= PAGE_SIZE / 2) ? 2 : 1;
+ efx_rx_config_page_split(efx);
+ if (efx->rx_buffer_order)
+ netif_dbg(efx, drv, efx->net_dev,
+ "RX buf len=%u; page order=%u batch=%u\n",
+ efx->rx_dma_len, efx->rx_buffer_order,
+ efx->rx_pages_per_batch);
+ else
+ netif_dbg(efx, drv, efx->net_dev,
+ "RX buf len=%u step=%u bpp=%u; page batch=%u\n",
+ efx->rx_dma_len, efx->rx_page_buf_step,
+ efx->rx_bufs_per_page, efx->rx_pages_per_batch);
/* RX filters also have scatter-enabled flags */
if (efx->rx_scatter != old_rx_scatter)
diff --git a/drivers/net/ethernet/sfc/efx.h b/drivers/net/ethernet/sfc/efx.h
index 211da79..8372da2 100644
--- a/drivers/net/ethernet/sfc/efx.h
+++ b/drivers/net/ethernet/sfc/efx.h
@@ -33,6 +33,7 @@ extern int efx_setup_tc(struct net_device *net_dev, u8 num_tc);
extern unsigned int efx_tx_max_skb_descs(struct efx_nic *efx);
/* RX */
+extern void efx_rx_config_page_split(struct efx_nic *efx);
extern int efx_probe_rx_queue(struct efx_rx_queue *rx_queue);
extern void efx_remove_rx_queue(struct efx_rx_queue *rx_queue);
extern void efx_init_rx_queue(struct efx_rx_queue *rx_queue);
diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index e22e75c..9bd433a 100644
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -825,7 +825,9 @@ struct efx_nic {
unsigned int rx_dma_len;
unsigned int rx_buffer_order;
unsigned int rx_buffer_truesize;
+ unsigned int rx_page_buf_step;
unsigned int rx_bufs_per_page;
+ unsigned int rx_pages_per_batch;
u8 rx_hash_key[40];
u32 rx_indir_table[128];
bool rx_scatter;
diff --git a/drivers/net/ethernet/sfc/rx.c b/drivers/net/ethernet/sfc/rx.c
index 4cc2ba4..a948b36 100644
--- a/drivers/net/ethernet/sfc/rx.c
+++ b/drivers/net/ethernet/sfc/rx.c
@@ -25,19 +25,15 @@
#include "selftest.h"
#include "workarounds.h"
-/* Number of RX descriptors pushed at once. */
-#define EFX_RX_BATCH 8
+/* Preferred number of descriptors to fill at once */
+#define EFX_RX_PREFERRED_BATCH 8U
/* Number of RX buffers to recycle pages for. When creating the RX page recycle
* ring, this number is divided by the number of buffers per page to calculate
* the number of pages to store in the RX page recycle ring.
*/
#define EFX_RECYCLE_RING_SIZE_IOMMU 4096
-#define EFX_RECYCLE_RING_SIZE_NOIOMMU (2 * EFX_RX_BATCH)
-
-/* Maximum length for an RX descriptor sharing a page */
-#define EFX_RX_HALF_PAGE ((PAGE_SIZE >> 1) - sizeof(struct efx_rx_page_state) \
- - EFX_PAGE_IP_ALIGN)
+#define EFX_RECYCLE_RING_SIZE_NOIOMMU (2 * EFX_RX_PREFERRED_BATCH)
/* Size of buffer allocated for skb header area. */
#define EFX_SKB_HEADERS 64u
@@ -95,6 +91,19 @@ static inline void efx_sync_rx_buffer(struct efx_nic *efx,
DMA_FROM_DEVICE);
}
+void efx_rx_config_page_split(struct efx_nic *efx)
+{
+ efx->rx_page_buf_step = ALIGN(efx->rx_dma_len + EFX_PAGE_IP_ALIGN,
+ L1_CACHE_BYTES);
+ efx->rx_bufs_per_page = efx->rx_buffer_order ? 1 :
+ ((PAGE_SIZE - sizeof(struct efx_rx_page_state)) /
+ efx->rx_page_buf_step);
+ efx->rx_buffer_truesize = (PAGE_SIZE << efx->rx_buffer_order) /
+ efx->rx_bufs_per_page;
+ efx->rx_pages_per_batch = DIV_ROUND_UP(EFX_RX_PREFERRED_BATCH,
+ efx->rx_bufs_per_page);
+}
+
/* Check the RX page recycle ring for a page that can be reused. */
static struct page *efx_reuse_page(struct efx_rx_queue *rx_queue)
{
@@ -134,10 +143,10 @@ static struct page *efx_reuse_page(struct efx_rx_queue *rx_queue)
*
* @rx_queue: Efx RX queue
*
- * This allocates memory for EFX_RX_BATCH receive buffers, maps them for DMA,
- * and populates struct efx_rx_buffers for each one. Return a negative error
- * code or 0 on success. If a single page can be split between two buffers,
- * then the page will either be inserted fully, or not at at all.
+ * This allocates a batch of pages, maps them for DMA, and populates
+ * struct efx_rx_buffers for each one. Return a negative error code or
+ * 0 on success. If a single page can be used for multiple buffers,
+ * then the page will either be inserted fully, or not at all.
*/
static int efx_init_rx_buffers(struct efx_rx_queue *rx_queue)
{
@@ -149,10 +158,8 @@ static int efx_init_rx_buffers(struct efx_rx_queue *rx_queue)
dma_addr_t dma_addr;
unsigned index, count;
- /* We can split a page between two buffers */
- BUILD_BUG_ON(EFX_RX_BATCH & 1);
-
- for (count = 0; count < EFX_RX_BATCH; ++count) {
+ count = 0;
+ do {
page = efx_reuse_page(rx_queue);
if (page == NULL) {
page = alloc_pages(__GFP_COLD | __GFP_COMP | GFP_ATOMIC,
@@ -174,32 +181,26 @@ static int efx_init_rx_buffers(struct efx_rx_queue *rx_queue)
state = page_address(page);
dma_addr = state->dma_addr;
}
- get_page(page);
dma_addr += sizeof(struct efx_rx_page_state);
page_offset = sizeof(struct efx_rx_page_state);
- split:
- index = rx_queue->added_count & rx_queue->ptr_mask;
- rx_buf = efx_rx_buffer(rx_queue, index);
- rx_buf->dma_addr = dma_addr + EFX_PAGE_IP_ALIGN;
- rx_buf->page = page;
- rx_buf->page_offset = page_offset + EFX_PAGE_IP_ALIGN;
- rx_buf->len = efx->rx_dma_len;
- ++rx_queue->added_count;
-
- if ((~count & 1) && (efx->rx_dma_len <= EFX_RX_HALF_PAGE)) {
- /* Use the second half of the page */
- get_page(page);
+ do {
+ index = rx_queue->added_count & rx_queue->ptr_mask;
+ rx_buf = efx_rx_buffer(rx_queue, index);
+ rx_buf->dma_addr = dma_addr + EFX_PAGE_IP_ALIGN;
+ rx_buf->page = page;
+ rx_buf->page_offset = page_offset + EFX_PAGE_IP_ALIGN;
+ rx_buf->len = efx->rx_dma_len;
rx_buf->flags = 0;
- dma_addr += (PAGE_SIZE >> 1);
- page_offset += (PAGE_SIZE >> 1);
- ++count;
- goto split;
- }
+ ++rx_queue->added_count;
+ get_page(page);
+ dma_addr += efx->rx_page_buf_step;
+ page_offset += efx->rx_page_buf_step;
+ } while (page_offset + efx->rx_page_buf_step <= PAGE_SIZE);
rx_buf->flags = EFX_RX_BUF_LAST_IN_PAGE;
- }
+ } while (++count < efx->rx_pages_per_batch);
return 0;
}
@@ -307,7 +308,8 @@ static void efx_recycle_rx_buffers(struct efx_channel *channel,
*/
void efx_fast_push_rx_descriptors(struct efx_rx_queue *rx_queue)
{
- unsigned fill_level;
+ struct efx_nic *efx = rx_queue->efx;
+ unsigned int fill_level, batch_size;
int space, rc = 0;
/* Calculate current fill level, and exit if we don't need to fill */
@@ -322,8 +324,9 @@ void efx_fast_push_rx_descriptors(struct efx_rx_queue *rx_queue)
rx_queue->min_fill = fill_level;
}
+ batch_size = efx->rx_pages_per_batch * efx->rx_bufs_per_page;
space = rx_queue->max_fill - fill_level;
- EFX_BUG_ON_PARANOID(space < EFX_RX_BATCH);
+ EFX_BUG_ON_PARANOID(space < batch_size);
netif_vdbg(rx_queue->efx, rx_status, rx_queue->efx->net_dev,
"RX queue %d fast-filling descriptor ring from"
@@ -340,7 +343,7 @@ void efx_fast_push_rx_descriptors(struct efx_rx_queue *rx_queue)
efx_schedule_slow_fill(rx_queue);
goto out;
}
- } while ((space -= EFX_RX_BATCH) >= EFX_RX_BATCH);
+ } while ((space -= batch_size) >= batch_size);
netif_vdbg(rx_queue->efx, rx_status, rx_queue->efx->net_dev,
"RX queue %d fast-filled descriptor ring "
@@ -708,7 +711,8 @@ void efx_init_rx_queue(struct efx_rx_queue *rx_queue)
/* Initialise limit fields */
max_fill = efx->rxq_entries - EFX_RXD_HEAD_ROOM;
- max_trigger = max_fill - EFX_RX_BATCH;
+ max_trigger =
+ max_fill - efx->rx_pages_per_batch * efx->rx_bufs_per_page;
if (rx_refill_threshold != 0) {
trigger = max_fill * min(rx_refill_threshold, 100U) / 100U;
if (trigger > max_trigger)
--
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.
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