diff mbox series

[v3] net/af_packet: cache align Rx/Tx structs

Message ID 20240426090502.100487-1-mattias.ronnblom@ericsson.com (mailing list archive)
State Accepted
Delegated to: Ferruh Yigit
Headers
Series [v3] net/af_packet: cache align Rx/Tx structs |

Checks

Context Check Description
ci/loongarch-compilation success Compilation OK
ci/loongarch-unit-testing success Unit Testing PASS
ci/Intel-compilation success Compilation OK
ci/intel-Testing success Testing PASS
ci/intel-Functional success Functional PASS
ci/iol-intel-Performance success Performance Testing PASS
ci/iol-mellanox-Performance success Performance Testing PASS
ci/iol-sample-apps-testing success Testing PASS
ci/iol-abi-testing success Testing PASS
ci/iol-unit-amd64-testing success Testing PASS
ci/iol-unit-arm64-testing success Testing PASS
ci/iol-broadcom-Performance success Performance Testing PASS
ci/iol-intel-Functional success Functional Testing PASS
ci/iol-broadcom-Functional success Functional Testing PASS
ci/iol-compile-amd64-testing fail Testing issues
ci/iol-compile-arm64-testing success Testing PASS

Commit Message

Mattias Rönnblom April 26, 2024, 9:05 a.m. UTC 
  Cache align Rx and Tx queue struct to avoid false sharing.

The RX struct happens to be 64 bytes on x86_64 already, so cache
alignment has no effect there, but it does on 32-bit ISAs.

The TX struct is 56 bytes on x86_64.

Both structs keep counters, and in the RX case they are updated even
for empty polls.

v3: Move __rte_cache_aligned directive to a MSVC-compatible location.

Fixes: 364e08f2bbc0 ("af_packet: add PMD for AF_PACKET-based virtual devices")
Cc: stable@dpdk.org

Signed-off-by: Mattias Rönnblom <mattias.ronnblom@ericsson.com>
---
 drivers/net/af_packet/rte_eth_af_packet.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Morten Brørup April 26, 2024, 9:22 a.m. UTC | #1 
> From: Mattias Rönnblom [mailto:mattias.ronnblom@ericsson.com]
> Sent: Friday, 26 April 2024 11.05
> 
> Cache align Rx and Tx queue struct to avoid false sharing.

Should an RTE_CACHE_GUARD be added at the end of these two structs?

If not,
Reviewed-by: Morten Brørup <mb@smartsharesystems.com>
Stephen Hemminger April 26, 2024, 3:10 p.m. UTC | #2 
On Fri, 26 Apr 2024 11:05:02 +0200
Mattias Rönnblom <mattias.ronnblom@ericsson.com> wrote:

> Cache align Rx and Tx queue struct to avoid false sharing.
> 
> The RX struct happens to be 64 bytes on x86_64 already, so cache
> alignment has no effect there, but it does on 32-bit ISAs.
> 
> The TX struct is 56 bytes on x86_64.
> 
> Both structs keep counters, and in the RX case they are updated even
> for empty polls.
> 
> v3: Move __rte_cache_aligned directive to a MSVC-compatible location.
> 
> Fixes: 364e08f2bbc0 ("af_packet: add PMD for AF_PACKET-based virtual devices")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Mattias Rönnblom <mattias.ronnblom@ericsson.com>

Looks good.

Acked-by: Stephen Hemminger <stephen@networkplumber.org>

If you want to go further with this:
   - could rx and tx rings be next to each other so that any of the lookahead
     in cpu helps, not hurts?
   - what about secondary process support
   - would sendmmsg() and recvmmsg() help for bursting.
Tyler Retzlaff April 26, 2024, 3:41 p.m. UTC | #3 
On Fri, Apr 26, 2024 at 11:05:02AM +0200, Mattias Rönnblom wrote:
> Cache align Rx and Tx queue struct to avoid false sharing.
> 
> The RX struct happens to be 64 bytes on x86_64 already, so cache
> alignment has no effect there, but it does on 32-bit ISAs.
> 
> The TX struct is 56 bytes on x86_64.
> 
> Both structs keep counters, and in the RX case they are updated even
> for empty polls.
> 
> v3: Move __rte_cache_aligned directive to a MSVC-compatible location.
> 
> Fixes: 364e08f2bbc0 ("af_packet: add PMD for AF_PACKET-based virtual devices")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Mattias Rönnblom <mattias.ronnblom@ericsson.com>
> ---
Acked-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
Ferruh Yigit April 29, 2024, 8:46 a.m. UTC | #4 
On 4/26/2024 4:41 PM, Tyler Retzlaff wrote:
> On Fri, Apr 26, 2024 at 11:05:02AM +0200, Mattias Rönnblom wrote:
>> Cache align Rx and Tx queue struct to avoid false sharing.
>>
>> The RX struct happens to be 64 bytes on x86_64 already, so cache
>> alignment has no effect there, but it does on 32-bit ISAs.
>>
>> The TX struct is 56 bytes on x86_64.
>>
>> Both structs keep counters, and in the RX case they are updated even
>> for empty polls.
>>
>> v3: Move __rte_cache_aligned directive to a MSVC-compatible location.
>>
>> Fixes: 364e08f2bbc0 ("af_packet: add PMD for AF_PACKET-based virtual devices")
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Mattias Rönnblom <mattias.ronnblom@ericsson.com>
>> ---
>
> Reviewed-by: Morten Brørup <mb@smartsharesystems.com>
> Acked-by: Stephen Hemminger <stephen@networkplumber.org>
> Acked-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
> 

Applied to dpdk-next-net/main, thanks.
diff mbox series

Patch

diff --git a/drivers/net/af_packet/rte_eth_af_packet.c b/drivers/net/af_packet/rte_eth_af_packet.c
index 397a32db58..6b7b16f348 100644
--- a/drivers/net/af_packet/rte_eth_af_packet.c
+++ b/drivers/net/af_packet/rte_eth_af_packet.c
@@ -6,6 +6,7 @@ 
  * All rights reserved.
  */
 
+#include <rte_common.h>
 #include <rte_string_fns.h>
 #include <rte_mbuf.h>
 #include <ethdev_driver.h>
@@ -39,7 +40,7 @@ 
 #define DFLT_FRAME_SIZE		(1 << 11)
 #define DFLT_FRAME_COUNT	(1 << 9)
 
-struct pkt_rx_queue {
+struct __rte_cache_aligned pkt_rx_queue {
 	int sockfd;
 
 	struct iovec *rd;
@@ -55,7 +56,7 @@  struct pkt_rx_queue {
 	volatile unsigned long rx_bytes;
 };
 
-struct pkt_tx_queue {
+struct __rte_cache_aligned pkt_tx_queue {
 	int sockfd;
 	unsigned int frame_data_size;