Free Memory Mac Os X

Recoverit Mac Data Recovery. When it comes to the free data recovery software for Mac, Recoverit.
There are times that when your Mac can slow down as more stuff is running in your system and your RAM is cluttering up. When you find Mac RAM is filling up due to increased workload on the OS X then the time for a Mac memory clean tool. By using MAC Memory Clean Apps, you can get free up inactive memory for other tasks.

FreeMemory for Mac is a utility to free up unneeded memory in your Mac OS X device. It is available for free from the App Store and download sites.

macOS Big Sur elevates the most advanced desktop operating system in the world to a new level of power and beauty. Experience Mac to the fullest with a refined new design. Enjoy the biggest Safari update ever. Discover new features for Maps and Messages. Get even more transparency around your privacy.

Chances are, your Mac can run macOS Big Sur

The following models are supported:

MacBook (2015 or later)
MacBook Air (2013 or later)
MacBook Pro (Late 2013 or later)
Mac mini (2014 or later)
iMac (2014 or later)
iMac Pro (2017 or later)
Mac Pro (2013 or later)

To see which model you have, click the Apple icon in your menu bar and choose About This Mac.

Make sure you’re ready to upgrade.

Before you upgrade, we recommend that you back up your Mac. If your Mac is running OS X Mavericks 10.9 or later, you can upgrade directly to macOS Big Sur. You’ll need the following:

OS X 10.9 or later
4GB of memory
35.5GB available storage on macOS Sierra or later*
Some features require an Apple ID; terms apply.
Some features require a compatible internet service provider; fees may apply.

Upgrading is free and easy

Upgrading from macOS Catalina 10.15 or Mojave 10.14?

Go to Software Update in System Preferences to find macOS Big Sur. Click Upgrade Now and follow the onscreen instructions.

Upgrading from an older version of macOS?

If you’re running any release from macOS 10.13 to 10.9, you can upgrade to macOS Big Sur from the App Store. If you’re running Mountain Lion 10.8, you will need to upgrade to El Capitan 10.11 first.

If you don’t have broadband access, you can upgrade your Mac at any Apple Store.

OS X 10.9 or later
4GB of memory
35.5GB available storage on macOS Sierra or later*

Some features require an Apple ID; terms apply.
Some features require a compatible internet service provider; fees may apply.

For details about your Mac model, click the Apple icon at the top left of your screen and choose About This Mac. These Mac models are compatible with macOS Big Sur:

MacBook (2015 or later)
MacBook Air (2013 or later)
MacBook Pro (Late 2013 or later)
Mac mini (2014 or later)

iMac (2014 or later)
iMac Pro (2017 or later)
Mac Pro (2013 or later)

Siri

Requires a broadband internet connection and microphone (built-in or external).

Hey Siri

Supported by the following Mac models:

MacBook Pro (2018 or later)
MacBook Air (2018 or later)
iMac Pro (2017 or later)

Dictation, Voice Control, and Voice Memos

Requires a microphone (built-in or external).

Spotlight Suggestions

Requires a broadband internet connection.

Gestures

Requires a Multi-Touch trackpad, Force Touch trackpad, Magic Trackpad, or Magic Mouse.

Force Touch gestures require a Force Touch trackpad.

VoiceOver gestures require a Multi-Touch trackpad, Force Touch trackpad, or Magic Trackpad.

Photo Booth

Requires a FaceTime or iSight camera (built-in or external) or USB video class (UVC) camera.

FaceTime

Audio calls require a microphone (built-in or external) and broadband internet connection.

Video calls require a built-in FaceTime camera, an iSight camera (built-in or external), or a USB video class (UVC) camera; and broadband internet connection.

Apple TV

High dynamic range (HDR) video playback is supported by the following Mac models:

MacBook Pro (2018 or later)
iMac Pro (2017 or later)
Mac Pro (2019) with Pro Display XDR

Dolby Atmos soundtrack playback is supported by the following Mac models:

MacBook Air (2018 or later)
MacBook Pro (2018 or later)

Sidecar

Supported by the following Mac models:

MacBook (2016 or later)
MacBook Air (2018 or later)
MacBook Pro (2016 or later)
Mac mini (2018 or later)
iMac (late 2015 or later)
iMac Pro (2017 or later)
Mac Pro (2019)

Supported by all iPad models with Apple Pencil support:

12.9-inch iPad Pro
11-inch iPad Pro
10.5-inch iPad Pro
9.7-inch iPad Pro
iPad (6th generation or later)
iPad mini (5th generation)
iPad Air (3rd and 4th generation)

Continuity Camera

Requires an iPhone or iPad that supports iOS 12 or later.

Continuity Sketch and Continuity Markup

Requires an iPhone with iOS 13 or later or an iPad with iPadOS 13 or later.

Handoff

Requires an iPhone or iPad with a Lightning connector or with USB-C and iOS 8 or later.

Instant Hotspot

Requires an iPhone or iPad with cellular connectivity, a Lightning connector or USB-C, and iOS 8.1 or later. Requires Personal Hotspot service through your carrier.

Universal Clipboard

Requires an iPhone or iPad with a Lightning connector or with USB-C and iOS 10 or later.

Auto Unlock

Requires an Apple Watch with watchOS 3 or later or an iPhone 5 or later.

Approve with Apple Watch

Requires an Apple Watch with watchOS 6 or later or an iPhone 6s or later with iOS 13 or later.

Apple Pay on the Web

Requires a MacBook Pro or MacBook Air with Touch ID, an iPhone 6 or later with iOS 10 or later, or an Apple Watch with watchOS 3 or later.

Phone Calling

Requires an iPhone with iOS 8 or later and an activated carrier plan.

SMS

Requires an iPhone with iOS 8.1 or later and an activated carrier plan.

Home

Requires an iPhone with iOS 12 or later and a configured Home app.

AirDrop

AirDrop to iOS and iPadOS devices requires an iPhone or iPad with a Lightning connector or with USB-C and iOS 7 or later.

AirPlay

AirPlay Mirroring requires an Apple TV (2nd generation or later).

AirPlay for web video requires an Apple TV (2nd generation or later).

Peer-to-peer AirPlay requires a Mac (2012 or later) and an Apple TV (3rd generation rev A, model A1469 or later) with Apple TV software 7.0 or later.

Time Machine

Requires an external storage device (sold separately).

Maps electric vehicle routing

Requires an iPhone with iOS 14 and a compatible electric vehicle.

Maps license plate restrictions

Requires an iPhone running iOS 14 or an iPad running iPadOS 14.

Boot Camp

Allows Boot Camp installations of Windows 10 on supported Mac models.

Exchange Support

Requires Microsoft Office 365, Exchange 2016, Exchange 2013, or Exchange Server 2010. Installing the latest Service Packs is recommended.

Windows Migration

Supports OS X 10.7 or later and Windows 7 or later.

App Store

Available only to persons age 13 or older in the U.S. and many other countries and regions.

Photos

The improved Retouch tool is supported on the following Mac models:

MacBook Pro (15-inch and 16-inch models) introduced in 2016 or later
iMac (Retina 5K models) introduced in 2014 or later
iMac (Retina 4K models) introduced in 2017 or later
iMac Pro (2017 or later)
Mac Pro introduced in 2013 or later

Apple Books
Apple News
App Store
Automator
Calculator
Calendar
Chess
Contacts
Dictionary
DVD Player
FaceTime
Find My
Font Book
Home
Image Capture
Launchpad
Mail
Maps

Messages
Mission Control
Music
Notes
Photo Booth
Photos
Podcasts
Preview
QuickTime Player
Reminders
Safari
Siri
Stickies
Stocks
System Preferences
TextEdit
Time Machine
TV
Voice Memos

Activity Monitor
AirPort Utility
Audio MIDI Setup
Bluetooth File Exchange
Boot Camp Assistant
ColorSync Utility
Console
Digital Color Meter
Disk Utility

Grapher
Keychain Access
Migration Assistant
Screenshot
Screen Time
Script Editor
Sidecar
System Information
Terminal
VoiceOver Utility

Arabic
Catalan
Croatian
Simplified Chinese
Traditional Chinese
Traditional Chinese (Hong Kong)
Czech
Danish
Dutch
English (Australia)
English (UK)
English (U.S.)
Finnish
French
French (Canada)
German
Greek
Hebrew
Hindi
Hungarian

Indonesian
Italian
Japanese
Korean
Malay
Norwegian
Polish
Brazilian Portuguese
Portuguese
Romanian
Russian
Slovak
Spanish
Spanish (Latin America)
Swedish
Thai
Turkish
Ukrainian
Vietnamese

Efficient memory management is an important aspect of writing high performance code in both OS X and iOS. Minimizing memory usage not only decreases your application’s memory footprint, it can also reduce the amount of CPU time it consumes. In order to properly tune your code though, you need to understand something about how the underlying system manages memory.

Both OS X and iOS include a fully-integrated virtual memory system that you cannot turn off; it is always on. Both systems also provide up to 4 gigabytes of addressable space per 32-bit process. In addition, OS X provides approximately 18 exabytes of addressable space for 64-bit processes. Even for computers that have 4 or more gigabytes of RAM available, the system rarely dedicates this much RAM to a single process.

To give processes access to their entire 4 gigabyte or 18 exabyte address space, OS X uses the hard disk to hold data that is not currently in use. As memory gets full, sections of memory that are not being used are written to disk to make room for data that is needed now. The portion of the disk that stores the unused data is known as the backing store because it provides the backup storage for main memory.

Although OS X supports a backing store, iOS does not. In iPhone applications, read-only data that is already on the disk (such as code pages) is simply removed from memory and reloaded from disk as needed. Writable data is never removed from memory by the operating system. Instead, if the amount of free memory drops below a certain threshold, the system asks the running applications to free up memory voluntarily to make room for new data. Applications that fail to free up enough memory are terminated.

Note: Unlike most UNIX-based operating systems, OS X does not use a preallocated disk partition for the backing store. Instead, it uses all of the available space on the machine’s boot partition.

The following sections introduce terminology and provide a brief overview of the virtual memory system used in both OS X and iOS. For more detailed information on how the virtual memory system works, see Kernel Programming Guide.

About Virtual Memory

Virtual memory allows an operating system to escape the limitations of physical RAM. The virtual memory manager creates a logical address space (or “virtual” address space) for each process and divides it up into uniformly-sized chunks of memory called pages. The processor and its memory management unit (MMU) maintain a page table to map pages in the program’s logical address space to hardware addresses in the computer’s RAM. When a program’s code accesses an address in memory, the MMU uses the page table to translate the specified logical address into the actual hardware memory address. This translation occurs automatically and is transparent to the running application.

As far as a program is concerned, addresses in its logical address space are always available. However, if an application accesses an address on a memory page that is not currently in physical RAM, a page fault occurs. When that happens, the virtual memory system invokes a special page-fault handler to respond to the fault immediately. The page-fault handler stops the currently executing code, locates a free page of physical memory, loads the page containing the needed data from disk, updates the page table, and then returns control to the program’s code, which can then access the memory address normally. This process is known as paging.

If there are no free pages available in physical memory, the handler must first release an existing page to make room for the new page. How the system release pages depends on the platform. In OS X, the virtual memory system often writes pages to the backing store. The backing store is a disk-based repository containing a copy of the memory pages used by a given process. Moving data from physical memory to the backing store is called paging out (or “swapping out”); moving data from the backing store back in to physical memory is called paging in (or “swapping in”). In iOS, there is no backing store and so pages are are never paged out to disk, but read-only pages are still be paged in from disk as needed.

Free Memory Mac Os X Update

In OS X and in earlier versions of iOS, the size of a page is 4 kilobytes. In later versions of iOS, A7- and A8-based systems expose 16-kilobyte pages to the 64-bit userspace backed by 4-kilobyte physical pages, while A9 systems expose 16-kilobyte pages backed by 16-kilobyte physical pages. These sizes determine how many kilobytes the system reads from disk when a page fault occurs. Disk thrashing can occur when the system spends a disproportionate amount of time handling page faults and reading and writing pages, rather than executing code for a program.

Paging of any kind, and disk thrashing in particular, affects performance negatively because it forces the system to spend a lot of time reading and writing to disk. Reading a page in from the backing store takes a significant amount of time and is much slower than reading directly from RAM. If the system has to write a page to disk before it can read another page from disk, the performance impact is even worse.

Details of the Virtual Memory System

The logical address space of a process consists of mapped regions of memory. Each mapped memory region contains a known number of virtual memory pages. Each region has specific attributes controlling such things as inheritance (portions of the region may be mapped from “parent” regions), write-protection, and whether it is wired (that is, it cannot be paged out). Because regions contain a known number of pages, they are page-aligned, meaning the starting address of the region is also the starting address of a page and the ending address also defines the end of a page.

The kernel associates a VM object with each region of the logical address space. The kernel uses VM objects to track and manage the resident and nonresident pages of the associated regions. A region can map to part of the backing store or to a memory-mapped file in the file system. Each VM object contains a map that associates regions with either the default pager or the vnode pager. The default pager is a system manager that manages the nonresident virtual memory pages in the backing store and fetches those pages when requested. The vnode pager implements memory-mapped file access. The vnode pager uses the paging mechanism to provide a window directly into a file. This mechanism lets you read and write portions of the file as if they were located in memory.

In addition to mapping regions to either the default or vnode pager, a VM object may also map regions to another VM object. The kernel uses this self referencing technique to implement copy-on-write regions. Copy-on-write regions allow different processes (or multiple blocks of code within a process) to share a page as long as none of them write to that page. When a process attempts to write to the page, a copy of the page is created in the logical address space of the process doing the writing. From that point forward, the writing process maintains its own separate copy of the page, which it can write to at any time. Copy-on-write regions let the system share large quantities of data efficiently in memory while still letting processes manipulate those pages directly (and safely) if needed. These types of regions are most commonly used for the data pages loaded from system frameworks.

Each VM object contains several fields, as shown in Table 1.

**Table 1** Fields of the VM object
Field	Description
Resident pages	A list of the pages of this region that are currently resident in physical memory.
Size	The size of the region, in bytes.
Pager	The pager responsible for tracking and handling the pages of this region in backing store.
Shadow	Used for copy-on-write optimizations.
Copy	Used for copy-on-write optimizations.
Attributes	Flags indicating the state of various implementation details.

If the VM object is involved in a copy-on-write (vm_copy) operation, the shadow and copy fields may point to other VM objects. Otherwise both fields are usually NULL.

Mac Os X Swap Free Memory

Wired Memory

Wired memory (also called resident memory) stores kernel code and data structures that must never be paged out to disk. Applications, frameworks, and other user-level software cannot allocate wired memory. However, they can affect how much wired memory exists at any time. For example, an application that creates threads and ports implicitly allocates wired memory for the required kernel resources that are associated with them.

Table 2 lists some of the wired-memory costs for application-generated entities.

**Table 2** Wired memory generated by user-level software
Resource	Wired Memory Used by Kernel
Process	16 kilobytes
Thread	blocked in a continuation—5 kilobytes; blocked—21 kilobytes
Mach port	116 bytes
Mapping	32 bytes
Library	2 kilobytes plus 200 bytes for each task that uses it
Memory region	160 bytes

Note: These measurements may change with each new release of the operating system. They are provided here to give you a rough estimate of the relative cost of system resource usage.

As you can see, every thread, process, and library contributes to the resident footprint of the system. In addition to your application using wired memory, however, the kernel itself requires wired memory for the following entities:

VM objects
the virtual memory buffer cache
I/O buffer caches
drivers

Wired data structures are also associated with the physical page and map tables used to store virtual-memory mapping information, Both of these entities scale with the amount of available physical memory. Consequently, when you add memory to a system, the amount of wired memory increases even if nothing else changes. When a computer is first booted into the Finder, with no other applications running, wired memory can consume approximately 14 megabytes of a 64 megabyte system and 17 megabytes of a 128 megabyte system.

Wired memory pages are not immediately moved back to the free list when they become invalid. Instead they are “garbage collected” when the free-page count falls below the threshold that triggers page out events.

Page Lists in the Kernel

The kernel maintains and queries three system-wide lists of physical memory pages:

The active list contains pages that are currently mapped into memory and have been recently accessed.
The inactive list contains pages that are currently resident in physical memory but have not been accessed recently. These pages contain valid data but may be removed from memory at any time.
The free list contains pages of physical memory that are not associated with any address space of VM object. These pages are available for immediate use by any process that needs them.

When the number of pages on the free list falls below a threshold (determined by the size of physical memory), the pager attempts to balance the queues. It does this by pulling pages from the inactive list. If a page has been accessed recently, it is reactivated and placed on the end of the active list. In OS X, if an inactive page contains data that has not been written to the backing store recently, its contents must be paged out to disk before it can be placed on the free list. (In iOS, modified but inactive pages must remain in memory and be cleaned up by the application that owns them.) If an inactive page has not been modified and is not permanently resident (wired), it is stolen (any current virtual mappings to it are destroyed) and added to the free list. Once the free list size exceeds the target threshold, the pager rests.

The kernel moves pages from the active list to the inactive list if they are not accessed; it moves pages from the inactive list to the active list on a soft fault (see Paging In Process). When virtual pages are swapped out, the associated physical pages are placed in the free list. Also, when processes explicitly free memory, the kernel moves the affected pages to the free list.

Paging Out Process

In OS X, when the number of pages in the free list dips below a computed threshold, the kernel reclaims physical pages for the free list by swapping inactive pages out of memory. To do this, the kernel iterates all resident pages in the active and inactive lists, performing the following steps:

If a page in the active list is not recently touched, it is moved to the inactive list.
If a page in the inactive list is not recently touched, the kernel finds the page’s VM object.
If the VM object has never been paged before, the kernel calls an initialization routine that creates and assigns a default pager object.
The VM object’s default pager attempts to write the page out to the backing store.
If the pager succeeds, the kernel frees the physical memory occupied by the page and moves the page from the inactive to the free list.

Free Memory Mac Os X Download

Note: In iOS, the kernel does not write pages out to a backing store. When the amount of free memory dips below the computed threshold, the kernel flushes pages that are inactive and unmodified and may also ask the running application to free up memory directly. For more information on responding to these notifications, see Responding to Low-Memory Warnings in iOS.

Paging In Process

The final phase of virtual memory management moves pages into physical memory, either from the backing store or from the file containing the page data. A memory access fault initiates the page-in process. A memory access fault occurs when code tries to access data at a virtual address that is not mapped to physical memory. There are two kinds of faults:

A soft fault occurs when the page of the referenced address is resident in physical memory but is currently not mapped into the address space of this process.
A hard fault occurs when the page of the referenced address is not in physical memory but is swapped out to backing store (or is available from a mapped file). This is what is typically known as a page fault.

When any type of fault occurs, the kernel locates the map entry and VM object for the accessed region. The kernel then goes through the VM object’s list of resident pages. If the desired page is in the list of resident pages, the kernel generates a soft fault. If the page is not in the list of resident pages, it generates a hard fault.

For soft faults, the kernel maps the physical memory containing the pages to the virtual address space of the process. The kernel then marks the specific page as active. If the fault involved a write operation, the page is also marked as modified so that it will be written to backing store if it needs to be freed later.

For hard faults, the VM object’s pager finds the page in the backing store or from the file on disk, depending on the type of pager. After making the appropriate adjustments to the map information, the pager moves the page into physical memory and places the page on the active list. As with a soft fault, if the fault involved a write operation, the page is marked as modified.