From: Artem Bityutskiy <dedekind1@gmail.com>
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Linux PM Mailing List <linux-pm@vger.kernel.org>,
Rui Zhang <rui.zhang@intel.com>, Jan Beulich <jbeulich@suse.com>,
Artem Bityutskiy <dedekind1@gmail.com>
Subject: [PATCH 2/2] intel_idle: fix SPR C6 optimization
Date: Wed, 27 Apr 2022 09:08:53 +0300 [thread overview]
Message-ID: <20220427060853.3975453-3-dedekind1@gmail.com> (raw)
In-Reply-To: <20220427060853.3975453-1-dedekind1@gmail.com>
From: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
This patch is a fix for the following 5.18-rc1 commit:
commit 3a9cf77b60dc intel_idle: add core C6 optimization for SPR
The Sapphire Rapids (SPR) C6 optimization was added to the end of the
'spr_idle_state_table_update()' function. However, the function has a
'return' which may happen before the optimization has a chance to run.
And this may prevent the optimization from happening.
This is an unlikely scenario, but possible if user boots with, say,
the 'intel_idle.preferred_cstates=6' kernel boot option.
This patch fixes the issue by eliminating the 'return'.
Suggested-by: Jan Beulich <jbeulich@suse.com>
Reported-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
---
drivers/idle/intel_idle.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index cf5ed4c1d02c..ae8649a809ea 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -1581,11 +1581,9 @@ static void __init spr_idle_state_table_update(void)
unsigned long long msr;
/* Check if user prefers C1E over C1. */
- if (preferred_states_mask & BIT(2)) {
- if (preferred_states_mask & BIT(1))
- /* Both can't be enabled, stick to the defaults. */
- return;
-
+ if ((preferred_states_mask & BIT(2)) &&
+ !(preferred_states_mask & BIT(1))) {
+ /* Disable C1 and enable C1E. */
spr_cstates[0].flags |= CPUIDLE_FLAG_UNUSABLE;
spr_cstates[1].flags &= ~CPUIDLE_FLAG_UNUSABLE;
--
2.35.1
next prev parent reply other threads:[~2022-04-27 6:09 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-27 6:08 [PATCH 0/2] intel_idle fixes for 5.18 Artem Bityutskiy
2022-04-27 6:08 ` [PATCH 1/2] intel_idle: fix the 'preferred_cstates' module parameter Artem Bityutskiy
2022-04-27 6:08 ` Artem Bityutskiy [this message]
2022-04-27 18:40 ` [PATCH 0/2] intel_idle fixes for 5.18 Rafael J. Wysocki
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=20220427060853.3975453-3-dedekind1@gmail.com \
--to=dedekind1@gmail.com \
--cc=jbeulich@suse.com \
--cc=linux-pm@vger.kernel.org \
--cc=rafael@kernel.org \
--cc=rui.zhang@intel.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.