From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 566B9C433EF for ; Tue, 7 Dec 2021 16:35:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232002AbhLGQjW (ORCPT ); Tue, 7 Dec 2021 11:39:22 -0500 Received: from mail-oi1-f169.google.com ([209.85.167.169]:42999 "EHLO mail-oi1-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230071AbhLGQjU (ORCPT ); Tue, 7 Dec 2021 11:39:20 -0500 Received: by mail-oi1-f169.google.com with SMTP id n66so28623255oia.9; Tue, 07 Dec 2021 08:35:49 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=31mjd/csqFEQKru4ee4D/rvYNR1wxLp+wwKZbiHux2g=; b=QvxLCriqtH6BSPLrSwkDPp2nwdNgYGtUTi+2/g2FjvYo8VfllzKuR9YsLgQFEzkeDg TND7Np0u8l+xIpT5fHefwDeF+7sx2WQziHd+NX5iyQeX9DZ5rPzMjlrH7L6shNX/DXei uuYRyoNAirI3gXDF5Pdgtz/iX80UhzXRBOsf4h3MREBeNcrMpuxnNVHE68GTvt86XbU1 dJ//xps/8T9ScrBQA/QF1PPmRVYuHZUwVZCxKoIfvOO7RQe/tikXtOZoB/HnK1YKcx69 fY0dHlg4u14AvQzREMh3N7ijGFXka7xs3Vl688EdNLiBTlLdiC8+c9YqO0zXT3Zq0Cd2 O5ig== X-Gm-Message-State: AOAM530Tf/wmuXxiuEJL+yhN5SrP9Rj3R1uz3p02j7focRMglmdGQtGx zU3TYGZ1ck084nAn1oTcmYKVyrKeTB43E+fCr8E= X-Google-Smtp-Source: ABdhPJzbBKOhECxZ5Fu3Bq2Y18qzwDOUfSloASSqP8c4P625s7x/rH/HOywYNNoMhCTzUVtD6pKCl5rKiys9YNoF4nc= X-Received: by 2002:a05:6808:e90:: with SMTP id k16mr6067044oil.166.1638894949491; Tue, 07 Dec 2021 08:35:49 -0800 (PST) MIME-Version: 1.0 References: <20211206122952.74139-1-kirill.shutemov@linux.intel.com> <20211206122952.74139-3-kirill.shutemov@linux.intel.com> In-Reply-To: <20211206122952.74139-3-kirill.shutemov@linux.intel.com> From: "Rafael J. Wysocki" Date: Tue, 7 Dec 2021 17:35:38 +0100 Message-ID: Subject: Re: [PATCH 2/4] ACPI: PM: Remove redundant cache flushing To: "Kirill A. Shutemov" Cc: "Rafael J. Wysocki" , Andi Kleen , Borislav Petkov , Dan Williams , Dave Hansen , "H. Peter Anvin" , Kuppuswamy Sathyanarayanan , ACPI Devel Maling List , Linux Kernel Mailing List , Ingo Molnar , "Rafael J. Wysocki" , Kuppuswamy Sathyanarayanan , Thomas Gleixner , Tony Luck , "the arch/x86 maintainers" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Mon, Dec 6, 2021 at 1:30 PM Kirill A. Shutemov 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 > --- > 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 >