From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932311Ab2EJPN5 (ORCPT ); Thu, 10 May 2012 11:13:57 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:63876 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757749Ab2EJPNy (ORCPT ); Thu, 10 May 2012 11:13:54 -0400 Date: Thu, 10 May 2012 08:13:46 -0700 From: Greg KH To: Alex Shi Cc: rob@landley.net, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, arnd@arndb.de, rostedt@goodmis.org, fweisbec@gmail.com, jeremy@goop.org, borislav.petkov@amd.com, riel@redhat.com, luto@mit.edu, avi@redhat.com, len.brown@intel.com, dhowells@redhat.com, fenghua.yu@intel.com, ak@linux.intel.com, cpw@sgi.com, steiner@sgi.com, akpm@linux-foundation.org, penberg@kernel.org, hughd@google.com, rientjes@google.com, kosaki.motohiro@jp.fujitsu.com, n-horiguchi@ah.jp.nec.com, paul.gortmaker@windriver.com, trenn@suse.de, tj@kernel.org, oleg@redhat.com, axboe@kernel.dk, a.p.zijlstra@chello.nl, kamezawa.hiroyu@jp.fujitsu.com, viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 7/7] x86/tlb: add tlb_flushall_factor into sysfs for user testing/tuning Message-ID: <20120510151346.GD17472@kroah.com> References: <1336626013-28413-1-git-send-email-alex.shi@intel.com> <1336626013-28413-8-git-send-email-alex.shi@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1336626013-28413-8-git-send-email-alex.shi@intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 10, 2012 at 01:00:13PM +0800, Alex Shi wrote: > kernel will replace cr3 rewrite with invlpg when > tlb_flush_entries <= active_tlb_entries / 2^tlb_flushall_factor > if tlb_flushall_factor is -1, kernel won't do this replacement. > > User can modify its value according to specific applications. > > Signed-off-by: Alex Shi > --- > Documentation/ABI/testing/sysfs-devices-system-cpu | 12 ++++++ > arch/x86/Kconfig.debug | 11 ++++++ > arch/x86/kernel/cpu/common.c | 37 ++++++++++++++++++++ > drivers/base/cpu.c | 4 ++ > include/linux/cpu.h | 4 ++ > 5 files changed, 68 insertions(+), 0 deletions(-) > > diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu > index e7be75b..05f8eb7 100644 > --- a/Documentation/ABI/testing/sysfs-devices-system-cpu > +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu > @@ -78,6 +78,18 @@ Description: Dynamic addition and removal of CPU's. This is not hotplug > the system. Information writtento the file to remove CPU's > is architecture specific. > > +What: /sys/devices/system/cpu/tlb_flushall_factor > +Date: May 2012 > +Contact: Linux kernel mailing list > +Description: tlb_flushall_factor show and setting interface > + tlb_flushall_factor shows the balance point in replacing cr3 > + writting with multiple 'invlpg'. It will do this replacement > + when flush_tlb_lines <= active_lines/2^tlb_flushall_factor > + If tlb_flushall_factor is -1, means the replacement will be > + disabled. > + > + User can set this for the specific CPU or application. Nowhere do you say this is x86 only, please fix that. > + > What: /sys/devices/system/cpu/cpu#/node > Date: October 2009 > Contact: Linux memory management mailing list > diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug > index e46c214..5b87493 100644 > --- a/arch/x86/Kconfig.debug > +++ b/arch/x86/Kconfig.debug > @@ -129,6 +129,17 @@ config DOUBLEFAULT > option saves about 4k and might cause you much additional grey > hair. > > +config DEBUG_TLBFLUSH > + bool "Enable user level tlb flush all setting" > + depends on DEBUG_KERNEL && (X86_64 || X86_INVLPG) > + ---help--- > + This option allows user tune tlb_flushall_factor knob that under > + /sys/devices/system/cpu, set to -1 means do tlb flush all for any > + multiple tlb lines evacuation demand. Otherwise kernel will use > + multiple 'invlpg' for the demand when > + flush_lines <= active_tlb_lines / 2^tlb_flushall_factor > + If in doubt, say "N" Yeah, another tunable that no one knows how to use. Really, why is this here at all? As others pointed out, this really looks like a debugging thing that almost no one will ever need, so please, put it in debugfs. > + > config IOMMU_DEBUG > bool "Enable IOMMU debugging" > depends on GART_IOMMU && DEBUG_KERNEL > diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c > index 8879d20..d1986c6 100644 > --- a/arch/x86/kernel/cpu/common.c > +++ b/arch/x86/kernel/cpu/common.c > @@ -481,6 +481,43 @@ void __cpuinit cpu_detect_tlb(struct cpuinfo_x86 *c) > tlb_flushall_factor); > } > > +#ifdef CONFIG_DEBUG_TLBFLUSH > +static ssize_t __tlb_flushall_factor_store(const char *buf, > + size_t count, int smt) > +{ > + short factor = 0; > + > + if (sscanf(buf, "%hd", &factor) != 1) > + return -EINVAL; > + > + tlb_flushall_factor = factor; > + > + return count; > +} > + > +static ssize_t tlb_flushall_factor_show(struct device *dev, > + struct device_attribute *attr, > + char *buf) > +{ > + return sprintf(buf, "%hd\n", tlb_flushall_factor); > +} > +static ssize_t tlb_flushall_factor_store(struct device *dev, > + struct device_attribute *attr, > + const char *buf, size_t count) > +{ > + return __tlb_flushall_factor_store(buf, count, 0); > +} > + > +static DEVICE_ATTR(tlb_flushall_factor, 0644, > + tlb_flushall_factor_show, > + tlb_flushall_factor_store); > + > +int __init create_sysfs_tlb_flushall_factor(struct device *dev) > +{ > + return device_create_file(dev, &dev_attr_tlb_flushall_factor); > +} > +#endif > + > void __cpuinit detect_ht(struct cpuinfo_x86 *c) > { > #ifdef CONFIG_X86_HT > diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c > index adf937b..dc0f77b 100644 > --- a/drivers/base/cpu.c > +++ b/drivers/base/cpu.c > @@ -331,6 +331,10 @@ void __init cpu_dev_init(void) > > cpu_dev_register_generic(); > > +#ifdef CONFIG_DEBUG_TLBFLUSH > + create_sysfs_tlb_flushall_factor(cpu_subsys.dev_root); > +#endif Do the #ifdef in the .h file, not the .c file please, no matter how you end up doing this (debugfs vs. sysfs.) thanks, greg k-h