fgets(3)/fread(3)/fscanf(3) etc. use mmap(2)/munmap(2) which leads to TLB shootdown interrupts to all dpdk app cores including RX cores. This can cause packet drops. Use read(2)/write(2) instead. Bugzilla ID: 440 Cc: stable@dpdk.org Signed-off-by: Mohsin Shaikh <mohsinshaikh@niometrics.com> --- drivers/net/mlx5/mlx5_stats.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/drivers/net/mlx5/mlx5_stats.c b/drivers/net/mlx5/mlx5_stats.c index 7603502..b2c09d8 100644 --- a/drivers/net/mlx5/mlx5_stats.c +++ b/drivers/net/mlx5/mlx5_stats.c @@ -3,11 +3,13 @@ * Copyright 2015 Mellanox Technologies, Ltd */ +#include <fcntl.h> #include <inttypes.h> #include <linux/sockios.h> #include <linux/ethtool.h> #include <stdint.h> #include <stdio.h> +#include <unistd.h> #include <rte_ethdev_driver.h> #include <rte_common.h> @@ -142,20 +144,23 @@ static inline void mlx5_read_ib_stat(struct mlx5_priv *priv, const char *ctr_name, uint64_t *stat) { - FILE *file; + int fd; + if (priv->sh) { MKSTR(path, "%s/ports/%d/hw_counters/%s", priv->sh->ibdev_path, priv->ibv_port, ctr_name); - - file = fopen(path, "rb"); - if (file) { - int n = fscanf(file, "%" SCNu64, stat); - - fclose(file); - if (n == 1) + fd = open(path, O_RDONLY); + if (fd != -1) { + char buf[21] = {'\0'}; + ssize_t n = read(fd, buf, sizeof(buf)); + + close(fd); + if (n != -1) { + *stat = strtoull(buf, NULL, 10); return; + } } } *stat = 0; -- 1.8.3.1
> -----Original Message-----
> From: Mohsin Shaikh <mohsinshaikh@niometrics.com>
> Sent: Thursday, April 9, 2020 16:37
> To: dev@dpdk.org
> Cc: stable@dpdk.org; Alexander Kozyrev <akozyrev@mellanox.com>; Mohsin
> Shaikh <mohsinshaikh@niometrics.com>
> Subject: [PATCH] net/mlx5: use open/read/close for reading ib stat
>
> fgets(3)/fread(3)/fscanf(3) etc. use mmap(2)/munmap(2) which leads to TLB
> shootdown interrupts to all dpdk app cores including RX cores.
> This can cause packet drops. Use read(2)/write(2) instead.
>
> Bugzilla ID: 440
> Cc: stable@dpdk.org
>
> Signed-off-by: Mohsin Shaikh <mohsinshaikh@niometrics.com>
> ---
Reviewed-by: Alexander Kozyrev <akozyrev@mellanox.com>
> -----Original Message-----
> From: dev <dev-bounces@dpdk.org> On Behalf Of Alexander Kozyrev
> Sent: Friday, April 10, 2020 1:21
> To: Mohsin Shaikh <mohsinshaikh@niometrics.com>; dev@dpdk.org
> Cc: stable@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] net/mlx5: use open/read/close for reading ib
> stat
>
> > -----Original Message-----
> > From: Mohsin Shaikh <mohsinshaikh@niometrics.com>
> > Sent: Thursday, April 9, 2020 16:37
> > To: dev@dpdk.org
> > Cc: stable@dpdk.org; Alexander Kozyrev <akozyrev@mellanox.com>;
> Mohsin
> > Shaikh <mohsinshaikh@niometrics.com>
> > Subject: [PATCH] net/mlx5: use open/read/close for reading ib stat
> >
> > fgets(3)/fread(3)/fscanf(3) etc. use mmap(2)/munmap(2) which leads to
> > TLB shootdown interrupts to all dpdk app cores including RX cores.
> > This can cause packet drops. Use read(2)/write(2) instead.
> >
> > Bugzilla ID: 440
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Mohsin Shaikh <mohsinshaikh@niometrics.com>
> > ---
>
> Reviewed-by: Alexander Kozyrev <akozyrev@mellanox.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>
Thank you, Mohsin for the patch.
Alexander, thank you for the review and test.
With best regards,
Slava
Hi,
> -----Original Message-----
> From: dev <dev-bounces@dpdk.org> On Behalf Of Mohsin Shaikh
> Sent: Thursday, April 9, 2020 11:37 PM
> To: dev@dpdk.org
> Cc: stable@dpdk.org; Alexander Kozyrev <akozyrev@mellanox.com>;
> Mohsin Shaikh <mohsinshaikh@niometrics.com>
> Subject: [dpdk-dev] [PATCH] net/mlx5: use open/read/close for reading ib
> stat
>
> fgets(3)/fread(3)/fscanf(3) etc. use mmap(2)/munmap(2) which leads
> to TLB shootdown interrupts to all dpdk app cores including RX cores.
> This can cause packet drops. Use read(2)/write(2) instead.
>
> Bugzilla ID: 440
> Cc: stable@dpdk.org
>
> Signed-off-by: Mohsin Shaikh <mohsinshaikh@niometrics.com>
> ---
> drivers/net/mlx5/mlx5_stats.c | 21 +++++++++++++--------
> 1 file changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/net/mlx5/mlx5_stats.c b/drivers/net/mlx5/mlx5_stats.c
> index 7603502..b2c09d8 100644
> --- a/drivers/net/mlx5/mlx5_stats.c
> +++ b/drivers/net/mlx5/mlx5_stats.c
> @@ -3,11 +3,13 @@
> * Copyright 2015 Mellanox Technologies, Ltd
> */
>
> +#include <fcntl.h>
> #include <inttypes.h>
> #include <linux/sockios.h>
> #include <linux/ethtool.h>
> #include <stdint.h>
> #include <stdio.h>
> +#include <unistd.h>
>
> #include <rte_ethdev_driver.h>
> #include <rte_common.h>
> @@ -142,20 +144,23 @@
> static inline void
> mlx5_read_ib_stat(struct mlx5_priv *priv, const char *ctr_name, uint64_t
> *stat)
> {
> - FILE *file;
> + int fd;
> +
> if (priv->sh) {
> MKSTR(path, "%s/ports/%d/hw_counters/%s",
> priv->sh->ibdev_path,
> priv->ibv_port,
> ctr_name);
> -
> - file = fopen(path, "rb");
> - if (file) {
> - int n = fscanf(file, "%" SCNu64, stat);
> -
> - fclose(file);
> - if (n == 1)
> + fd = open(path, O_RDONLY);
> + if (fd != -1) {
> + char buf[21] = {'\0'};
> + ssize_t n = read(fd, buf, sizeof(buf));
> +
> + close(fd);
> + if (n != -1) {
> + *stat = strtoull(buf, NULL, 10);
> return;
> + }
> }
> }
> *stat = 0;
> --
> 1.8.3.1
Patch rebased and applied to next-net-mlx,
Kindest regards
Raslan Darawsheh