From: Bhaskar Upadhaya <bhaskar.upadhaya.linux@gmail.com>
To: Bhaskar Upadhaya <bupadhaya@marvell.com>,
rafael@kernel.org, lenb@kernel.org
Cc: linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org,
linux-edac@vger.kernel.org, gkulkarni@marvell.com,
rrichter@marvell.com
Subject: Re: [RFC PATCH] apei/ghes: fix ghes_poll_func by registering in non-deferrable mode
Date: Thu, 2 Jan 2020 16:19:15 +0530 [thread overview]
Message-ID: <CAEYJA6qm0tpkOd81L6mG9OhtB4FFmTOMN-SfM2FjbibCvWkMHQ@mail.gmail.com> (raw)
In-Reply-To: <1576652618-27017-1-git-send-email-bupadhaya@marvell.com>
Hi Rafael, Len
Hope you get time to look into this patch.
Regards
--Bhaskar
On Wed, Dec 18, 2019 at 12:34 PM Bhaskar Upadhaya <bupadhaya@marvell.com> wrote:
>
> Currently Linux register ghes_poll_func with TIMER_DEFERRABLE flag,
> because of which it is serviced when the CPU eventually wakes up with a
> subsequent non-deferrable timer and not at the configured polling interval.
>
> For polling mode, the polling interval configured by firmware should not
> be exceeded as per ACPI_6_3 spec[refer Table 18-394], So Timer need to
> be configured in non-deferrable mode by removing TIMER_DEFERRABLE flag.
> With NO_HZ enabled and timer callback being configured in non-deferrable
> mode, timer callback will get called exactly after polling interval.
>
> Impact of removing TIMER_DEFFERABLE flag
> - With NO_HZ enabled, additional timer ticks and unnecessary wakeups of
> the cpu happens exactly after polling interval.
>
> - If polling interval is too small than polling function will be called
> too frequently which may stall the cpu.
>
> Signed-off-by: Bhaskar Upadhaya <bupadhaya@marvell.com>
> ---
> drivers/acpi/apei/ghes.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
> index 777f6f7122b4..c8f9230f69fb 100644
> --- a/drivers/acpi/apei/ghes.c
> +++ b/drivers/acpi/apei/ghes.c
> @@ -1181,7 +1181,7 @@ static int ghes_probe(struct platform_device *ghes_dev)
>
> switch (generic->notify.type) {
> case ACPI_HEST_NOTIFY_POLLED:
> - timer_setup(&ghes->timer, ghes_poll_func, TIMER_DEFERRABLE);
> + timer_setup(&ghes->timer, ghes_poll_func, 0);
> ghes_add_timer(ghes);
> break;
> case ACPI_HEST_NOTIFY_EXTERNAL:
> --
> 2.17.1
>
next prev parent reply other threads:[~2020-01-02 10:49 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-18 7:03 [RFC PATCH] apei/ghes: fix ghes_poll_func by registering in non-deferrable mode Bhaskar Upadhaya
2020-01-02 10:49 ` Bhaskar Upadhaya [this message]
2020-01-02 18:01 ` Borislav Petkov
2020-01-06 11:03 ` Bhaskar Upadhaya
2020-01-06 13:09 ` Borislav Petkov
2020-01-07 11:03 ` Bhaskar Upadhaya
2020-01-07 13:04 ` Robert Richter
2020-01-07 20:02 ` Borislav Petkov
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=CAEYJA6qm0tpkOd81L6mG9OhtB4FFmTOMN-SfM2FjbibCvWkMHQ@mail.gmail.com \
--to=bhaskar.upadhaya.linux@gmail.com \
--cc=bupadhaya@marvell.com \
--cc=gkulkarni@marvell.com \
--cc=lenb@kernel.org \
--cc=linux-acpi@vger.kernel.org \
--cc=linux-edac@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=rafael@kernel.org \
--cc=rrichter@marvell.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).