From: "Rafael J. Wysocki" <rafael@kernel.org>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
Andi Kleen <ak@linux.intel.com>, Borislav Petkov <bp@alien8.de>,
Dan Williams <dan.j.williams@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Tony Luck <tony.luck@intel.com>,
"the arch/x86 maintainers" <x86@kernel.org>
Subject: Re: [PATCH 2/4] ACPI: PM: Remove redundant cache flushing
Date: Tue, 7 Dec 2021 17:35:38 +0100 [thread overview]
Message-ID: <CAJZ5v0hGnvX2a1bsoUSqV4Vf0LE6P6wTjk4ZPT7JTLvSAL7z_g@mail.gmail.com> (raw)
In-Reply-To: <20211206122952.74139-3-kirill.shutemov@linux.intel.com>
On Mon, Dec 6, 2021 at 1:30 PM Kirill A. Shutemov
<kirill.shutemov@linux.intel.com> wrote:
>
> ACPICA code takes care about cache flushing on S1/S2/S3 in
> acpi_hw_extended_sleep() and acpi_hw_legacy_sleep().
>
> acpi_suspend_enter() calls into ACPICA code via acpi_enter_sleep_state()
> for S1 or x86_acpi_suspend_lowlevel() for S3. It only need to flush
> cache for S2 (not sure if this call path is ever used for S2).
>
> acpi_sleep_prepare() call tree:
> __acpi_pm_prepare()
> acpi_pm_prepare()
> acpi_suspend_ops::prepare_late()
> acpi_hibernation_ops::pre_snapshot()
> acpi_hibernation_ops::prepare()
> acpi_suspend_begin_old()
> acpi_suspend_begin_old::begin()
> acpi_hibernation_begin_old()
> acpi_hibernation_ops_old::acpi_hibernation_begin_old()
> acpi_power_off_prepare()
> pm_power_off_prepare()
>
> Hibernation (S4) and Power Off (S5) don't require cache flushing. So,
> the only interesting callsites are acpi_suspend_ops::prepare_late() and
> acpi_suspend_begin_old::begin(). Both of them have cache flush on
> ->enter() operation in acpi_suspend_enter().
>
> Remove redundant ACPI_FLUSH_CPU_CACHE() in acpi_sleep_prepare() and
> acpi_suspend_enter().
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> ---
> drivers/acpi/sleep.c | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
> index eaa47753b758..14e8df0ac762 100644
> --- a/drivers/acpi/sleep.c
> +++ b/drivers/acpi/sleep.c
> @@ -73,7 +73,6 @@ static int acpi_sleep_prepare(u32 acpi_state)
> acpi_set_waking_vector(acpi_wakeup_address);
>
> }
> - ACPI_FLUSH_CPU_CACHE();
> #endif
> pr_info("Preparing to enter system sleep state S%d\n", acpi_state);
> acpi_enable_wakeup_devices(acpi_state);
> @@ -566,15 +565,15 @@ static int acpi_suspend_enter(suspend_state_t pm_state)
> u32 acpi_state = acpi_target_sleep_state;
> int error;
>
> - ACPI_FLUSH_CPU_CACHE();
> -
> trace_suspend_resume(TPS("acpi_suspend"), acpi_state, true);
> switch (acpi_state) {
> case ACPI_STATE_S1:
> barrier();
> status = acpi_enter_sleep_state(acpi_state);
> break;
> -
> + case ACPI_STATE_S2:
> + ACPI_FLUSH_CPU_CACHE();
> + break;
I don't think this is needed for S2, because the function doesn't do
anything low-level in that case and simply returns (IOW, S2 isn't
really supported).
> case ACPI_STATE_S3:
> if (!acpi_suspend_lowlevel)
> return -ENOSYS;
> --
> 2.32.0
>
next prev parent reply other threads:[~2021-12-07 16:35 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <YZPbQVwWOJCrAH78@zn.tnic>
2021-11-19 4:03 ` [PATCH v2] x86: Skip WBINVD instruction for VM guest Kuppuswamy Sathyanarayanan
2021-11-25 0:40 ` Thomas Gleixner
2021-12-02 22:21 ` Kirill A. Shutemov
2021-12-02 22:38 ` Dave Hansen
2021-12-02 23:48 ` Thomas Gleixner
2021-12-03 23:49 ` Kirill A. Shutemov
2021-12-04 0:20 ` Dave Hansen
2021-12-04 0:54 ` Kirill A. Shutemov
2021-12-06 15:35 ` Dave Hansen
2021-12-06 16:39 ` Dan Williams
2021-12-06 16:53 ` Dave Hansen
2021-12-06 17:51 ` Dan Williams
2021-12-04 20:27 ` Rafael J. Wysocki
2021-12-06 12:29 ` [PATCH 0/4] ACPI/ACPICA: Only flush caches on S1/S2/S3 and C3 Kirill A. Shutemov
2021-12-06 12:29 ` [PATCH 1/4] ACPICA: Do not flush cache for on entering S4 and S5 Kirill A. Shutemov
2021-12-08 14:58 ` Rafael J. Wysocki
2021-12-06 12:29 ` [PATCH 2/4] ACPI: PM: Remove redundant cache flushing Kirill A. Shutemov
2021-12-07 16:35 ` Rafael J. Wysocki [this message]
2021-12-09 13:32 ` Kirill A. Shutemov
2021-12-17 18:04 ` Rafael J. Wysocki
2021-12-06 12:29 ` [PATCH 3/4] ACPI: processor idle: Only flush cache on entering C3 Kirill A. Shutemov
2021-12-06 15:03 ` Peter Zijlstra
2021-12-08 16:26 ` Rafael J. Wysocki
2021-12-09 13:33 ` Kirill A. Shutemov
2021-12-17 17:58 ` Rafael J. Wysocki
2021-12-06 12:29 ` [PATCH 4/4] ACPI: PM: Avoid cache flush on entering S4 Kirill A. Shutemov
2021-12-08 15:10 ` Rafael J. Wysocki
2021-12-08 16:04 ` Kirill A. Shutemov
2021-12-08 16:16 ` 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=CAJZ5v0hGnvX2a1bsoUSqV4Vf0LE6P6wTjk4ZPT7JTLvSAL7z_g@mail.gmail.com \
--to=rafael@kernel.org \
--cc=ak@linux.intel.com \
--cc=bp@alien8.de \
--cc=dan.j.williams@intel.com \
--cc=dave.hansen@linux.intel.com \
--cc=hpa@zytor.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=knsathya@kernel.org \
--cc=linux-acpi@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=rjw@rjwysocki.net \
--cc=sathyanarayanan.kuppuswamy@linux.intel.com \
--cc=tglx@linutronix.de \
--cc=tony.luck@intel.com \
--cc=x86@kernel.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).