From: Jeremy Linton <jeremy.linton at arm.com>
To: devel@acpica.org
Subject: [Devel] [PATCH v5 0/1] Disable FIE on machines with slow counters
Date: Mon, 12 Sep 2022 15:37:21 -0500 [thread overview]
Message-ID: <20220912203722.205185-1-jeremy.linton@arm.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 1304 bytes --]
FIE assumes the delivered/relative perf registers are fast to read so
it goes ahead and hits them quite frequently. On a couple of Arm
platforms though they end up in PCC regions which require mailbox
handshaking with other parts of the platform.
This results in a lot of overhead in the cppc_fie task. As such lets
runtime disable FIE if we detect it enabled on one of those platforms.
Lastly, allow the user to override this decision via a module parameter.
v1->v2:
Apply Rafael's review comments.
Move the MODULE_PARAM into the ifdef
Fix compiler warning when ACPI_CPPC_LIB is disabled.
v2->v3:
Tristate the module param so FIE can be forced on/off
Bump pr_debug to pr_info if FIE is disabled due to PCC regions
Switch ACPI_CPPC_CPUFREQ_FIE off by default
v3->v4:
No functional change, resend due to email addr issues
v4->v5:
Minor whitespace, comment wording, if/case conversion
Drop the ACPI_CPPC_CPUFREQ_FIE disable config change added in v3
Jeremy Linton (1):
ACPI: CPPC: Disable FIE if registers in PCC regions
drivers/acpi/cppc_acpi.c | 42 ++++++++++++++++++++++++++++++++++
drivers/cpufreq/cppc_cpufreq.c | 25 ++++++++++++++++----
include/acpi/cppc_acpi.h | 5 ++++
3 files changed, 68 insertions(+), 4 deletions(-)
--
2.37.1
reply other threads:[~2022-09-12 20:37 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
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=20220912203722.205185-1-jeremy.linton@arm.com \
--to=devel@acpica.org \
/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 read-only IMAP folder(s) and NNTP newsgroup(s).