From: Ferruh Yigit <ferruh.yigit@amd.com>
To: "Mattias Rönnblom" <mattias.ronnblom@ericsson.com>,
"John W . Linville" <linville@tuxdriver.com>
Cc: dev@dpdk.org, hofors@lysator.liu.se,
Tyler Retzlaff <roretzla@linux.microsoft.com>
Subject: Re: [PATCH] net/af_packet: cache align Rx/Tx structs
Date: Tue, 23 Apr 2024 12:15:27 +0100 [thread overview]
Message-ID: <6f7aabcb-2c12-4cfe-ae9d-73b42bfd4977@amd.com> (raw)
In-Reply-To: <20240423090813.94110-1-mattias.ronnblom@ericsson.com>
On 4/23/2024 10:08 AM, Mattias Rönnblom wrote:
> Cache align Rx and Tx queue struct to avoid false sharing.
>
> RX struct happens to be 64 bytes on x86_64 already, so cache alignment
> makes no change there, but it does on 32-bit ISAs.
>
> TX struct is 56 bytes on x86_64.
>
Hi Mattias,
No objection to the patch. Is the improvement theoretical or do you
measure any improvement practically, if so how much is the improvement?
> Both structs keep counters, and in the RX case they are updated even
> for empty polls.
>
Do you think does it help if move 'rx_pkts' & 'rx_bytes' update within
the loop?
> 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(-)
>
> diff --git a/drivers/net/af_packet/rte_eth_af_packet.c b/drivers/net/af_packet/rte_eth_af_packet.c
> index 397a32db58..28aeb7d08e 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>
> @@ -53,7 +54,7 @@ struct pkt_rx_queue {
>
> volatile unsigned long rx_pkts;
> volatile unsigned long rx_bytes;
> -};
> +} __rte_cache_aligned;
>
Latest location for '__rte_cache_aligned' tag is at the beginning of the
struct [1], so something like:
`struct __rte_cache_aligned pkt_rx_queue {`
[1]
https://patchwork.dpdk.org/project/dpdk/list/?series=31746&state=%2A&archive=both
next prev parent reply other threads:[~2024-04-23 11:15 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-23 9:08 Mattias Rönnblom
2024-04-23 11:15 ` Ferruh Yigit [this message]
2024-04-23 20:56 ` Mattias Rönnblom
2024-04-24 0:27 ` Honnappa Nagarahalli
2024-04-24 6:28 ` Mattias Rönnblom
2024-04-24 10:21 ` Ferruh Yigit
2024-04-24 10:28 ` Bruce Richardson
2024-04-24 18:02 ` Ferruh Yigit
2024-04-24 11:57 ` Mattias Rönnblom
2024-04-24 17:50 ` Ferruh Yigit
2024-04-24 19:13 ` Stephen Hemminger
2024-04-24 22:27 ` Mattias Rönnblom
2024-04-24 23:55 ` Stephen Hemminger
2024-04-25 9:26 ` Mattias Rönnblom
2024-04-25 9:49 ` Morten Brørup
2024-04-25 14:04 ` Ferruh Yigit
2024-04-25 15:06 ` Mattias Rönnblom
2024-04-25 16:21 ` Ferruh Yigit
2024-04-25 15:07 ` Stephen Hemminger
2024-04-25 14:08 ` Ferruh Yigit
2024-04-25 15:08 ` Mattias Rönnblom
2024-04-25 15:35 ` Ferruh Yigit
2024-04-26 7:25 ` Mattias Rönnblom
2024-04-26 7:38 ` Mattias Rönnblom
2024-04-26 8:27 ` Ferruh Yigit
2024-04-26 10:20 ` Mattias Rönnblom
2024-04-26 9:05 ` [PATCH v3] " Mattias Rönnblom
2024-04-26 9:22 ` Morten Brørup
2024-04-26 15:10 ` Stephen Hemminger
2024-04-26 15:41 ` Tyler Retzlaff
2024-04-29 8:46 ` Ferruh Yigit
2024-04-26 21:27 ` [PATCH] " Patrick Robb
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