Messages in this thread |  | | | Date | Thu, 10 May 2012 08:13:46 -0700 | | From | Greg KH <> | | Subject | Re: [PATCH v4 7/7] x86/tlb: add tlb_flushall_factor into sysfs for user testing/tuning |
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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 <alex.shi@intel.com> > --- > 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 <linux-kernel@vger.kernel.org> > +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 <linux-mm@kvack.org> > 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
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