From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753543AbbGaQqr (ORCPT ); Fri, 31 Jul 2015 12:46:47 -0400 Received: from mail-qk0-f176.google.com ([209.85.220.176]:33730 "EHLO mail-qk0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753482AbbGaQqp (ORCPT ); Fri, 31 Jul 2015 12:46:45 -0400 From: Len Brown To: rjw@rjwysocki.net, linux-pm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Len Brown Subject: [PATCH 1/1] suspend: make sync() on suspend-to-RAM build-time optional Date: Fri, 31 Jul 2015 12:46:17 -0400 Message-Id: <674dcf60fc85324b41479fcec930d64126c09fb1.1438360540.git.len.brown@intel.com> X-Mailer: git-send-email 2.5.0 In-Reply-To: <1438361177-23201-1-git-send-email-lenb@kernel.org> References: <1438361177-23201-1-git-send-email-lenb@kernel.org> Reply-To: Len Brown Organization: Intel Open Source Technology Center Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Len Brown The Linux kernel suspend path has traditionally invoked sys_sync() before freezing user threads. But sys_sync() can be expensive, and some user-space OS's do not want the kernel to pay the cost of sys_sync() on every suspend -- preferring invoke sync() from user-space if/when they want it. So make sys_sync on suspend build-time optional. The default is unchanged. Signed-off-by: Len Brown --- kernel/power/Kconfig | 10 ++++++++++ kernel/power/suspend.c | 2 ++ 2 files changed, 12 insertions(+) diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig index 7e01f78..80afa8a 100644 --- a/kernel/power/Kconfig +++ b/kernel/power/Kconfig @@ -18,6 +18,16 @@ config SUSPEND_FREEZER Turning OFF this setting is NOT recommended! If in doubt, say Y. +config SUSPEND_SKIP_SYNC + bool "Skip kernel's sys_sync() on suspend to RAM/standby" + depends on SUSPEND + depends on EXPERT + help + Delete the kernel sys_sync() before freezing user processes. + Some operating systems prefer not to pay this cost on every + invocation of suspend, or they are content with invoking sync() + from user-space before invoking suspend. + config HIBERNATE_CALLBACKS bool diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c index 8d7a1ef..4a942ee 100644 --- a/kernel/power/suspend.c +++ b/kernel/power/suspend.c @@ -482,11 +482,13 @@ static int enter_state(suspend_state_t state) if (state == PM_SUSPEND_FREEZE) freeze_begin(); +#ifndef CONFIG_SUSPEND_SKIP_SYNC trace_suspend_resume(TPS("sync_filesystems"), 0, true); printk(KERN_INFO "PM: Syncing filesystems ... "); sys_sync(); printk("done.\n"); trace_suspend_resume(TPS("sync_filesystems"), 0, false); +#endif pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]); error = suspend_prepare(state); -- 2.5.0