From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: Matan Azrad <matan@nvidia.com>, dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH] vdpa/mlx5: fix polling threads scheduling
Date: Mon, 8 Feb 2021 12:17:09 +0100 [thread overview]
Message-ID: <e673fa7c-639c-3729-5273-2bc483135cd6@redhat.com> (raw)
In-Reply-To: <1612776481-151396-1-git-send-email-matan@nvidia.com>
On 2/8/21 10:28 AM, Matan Azrad wrote:
> When the event mode is with 0 fixed delay, the polling-thread will never
> give-up CPU.
>
> So, when multi-polling-threads are active, the context-switch between
> them will be managed by the system which may affect latency according to
> the time-out decided by the system.
>
> In order to fix multi-devices polling thread scheduling, this patch
> forces rescheduling for each CQ poll iteration.
>
> Move the polling thread to SCHED_RR mode with maximum priority to
> complete the fairness.
>
> Fixes: 6956a48cabbb ("vdpa/mlx5: set polling mode default delay to zero")
>
> Signed-off-by: Matan Azrad <matan@nvidia.com>
> ---
> drivers/vdpa/mlx5/mlx5_vdpa_event.c | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/drivers/vdpa/mlx5/mlx5_vdpa_event.c b/drivers/vdpa/mlx5/mlx5_vdpa_event.c
> index 0f635ff..86adc86 100644
> --- a/drivers/vdpa/mlx5/mlx5_vdpa_event.c
> +++ b/drivers/vdpa/mlx5/mlx5_vdpa_event.c
> @@ -232,6 +232,9 @@
> }
> if (priv->timer_delay_us)
> usleep(priv->timer_delay_us);
> + else
> + /* Give-up CPU to improve polling threads scheduling. */
> + pthread_yield();
> }
>
> static void *
> @@ -500,6 +503,9 @@
> rte_cpuset_t cpuset;
> pthread_attr_t attr;
> char name[16];
> + const struct sched_param sp = {
> + .sched_priority = sched_get_priority_max(SCHED_RR),
> + };
>
> if (!priv->eventc)
> /* All virtqs are in poll mode. */
> @@ -520,6 +526,16 @@
> DRV_LOG(ERR, "Failed to set thread affinity.");
> return -1;
> }
> + ret = pthread_attr_setschedpolicy(&attr, SCHED_RR);
> + if (ret) {
> + DRV_LOG(ERR, "Failed to set thread sched policy = RR.");
> + return -1;
> + }
> + ret = pthread_attr_setschedparam(&attr, &sp);
> + if (ret) {
> + DRV_LOG(ERR, "Failed to set thread priority.");
> + return -1;
> + }
> ret = pthread_create(&priv->timer_tid, &attr,
> mlx5_vdpa_poll_handle, (void *)priv);
> if (ret) {
>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
next prev parent reply other threads:[~2021-02-08 11:17 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-08 9:28 Matan Azrad
2021-02-08 11:17 ` Maxime Coquelin [this message]
2021-02-09 3:15 ` Xueming(Steven) Li
2021-02-10 21:17 ` Thomas Monjalon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=e673fa7c-639c-3729-5273-2bc483135cd6@redhat.com \
--to=maxime.coquelin@redhat.com \
--cc=dev@dpdk.org \
--cc=matan@nvidia.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).