diff mbox series

[net-next,v3,2/4] net: stmmac: Set page_pool_params.max_len to a precise size

Message ID 538f87c8bdd0ba9e2b9cb5cd0e2964511c001890.1736910454.git.0x1207@gmail.com (mailing list archive)
State New
Delegated to: Netdev Maintainers
Headers show
Series net: stmmac: RX performance improvement | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1 this patch: 1
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers warning 7 maintainers not CCed: hawk@kernel.org rmk+kernel@armlinux.org.uk ast@kernel.org john.fastabend@gmail.com daniel@iogearbox.net alexandre.torgue@foss.st.com bpf@vger.kernel.org
netdev/build_clang success Errors and warnings before: 3 this patch: 3
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1 this patch: 1
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 15 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 36 this patch: 36
netdev/source_inline success Was 0 now: 0
netdev/contest fail net-next-2025-01-15--06-00 (tests: 872)

Commit Message

Furong Xu Jan. 15, 2025, 3:27 a.m. UTC 
DMA engine will always write no more than dma_buf_sz bytes of a received
frame into a page buffer, the remaining spaces are unused or used by CPU
exclusively.
Setting page_pool_params.max_len to almost the full size of page(s) helps
nothing more, but wastes more CPU cycles on cache maintenance.

For a standard MTU of 1500, then dma_buf_sz is assigned to 1536, and this
patch brings ~16.9% driver performance improvement in a TCP RX
throughput test with iPerf tool on a single isolated Cortex-A65 CPU
core, from 2.43 Gbits/sec increased to 2.84 Gbits/sec.

Signed-off-by: Furong Xu <0x1207@gmail.com>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 2 +-
 drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.h  | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 1d98a5e8c98c..811e2d372abf 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -2059,7 +2059,7 @@  static int __alloc_dma_rx_desc_resources(struct stmmac_priv *priv,
 	pp_params.dev = priv->device;
 	pp_params.dma_dir = xdp_prog ? DMA_BIDIRECTIONAL : DMA_FROM_DEVICE;
 	pp_params.offset = stmmac_rx_offset(priv);
-	pp_params.max_len = STMMAC_MAX_RX_BUF_SIZE(num_pages);
+	pp_params.max_len = dma_conf->dma_buf_sz;
 
 	rx_q->page_pool = page_pool_create(&pp_params);
 	if (IS_ERR(rx_q->page_pool)) {
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.h b/drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.h
index 896dc987d4ef..77ce8cfbe976 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_xdp.h
@@ -4,7 +4,6 @@ 
 #ifndef _STMMAC_XDP_H_
 #define _STMMAC_XDP_H_
 
-#define STMMAC_MAX_RX_BUF_SIZE(num)	(((num) * PAGE_SIZE) - XDP_PACKET_HEADROOM)
 #define STMMAC_RX_DMA_ATTR	(DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_WEAK_ORDERING)
 
 int stmmac_xdp_setup_pool(struct stmmac_priv *priv, struct xsk_buff_pool *pool,