Memory pressure mac os

Просмотр данных об использовании памяти в приложении «Мониторинг системы» на Mac

Можно посмотреть объем системной памяти, используемой на компьютере Mac.

В приложении «Мониторинг системы» на Mac нажмите «Память» (или воспользуйтесь панелью Touch Bar), чтобы просмотреть следующую информацию внизу окна.

Нагрузка на память. Графическое представление того, насколько эффективно память решает стоящие перед Вами задачи.

Нагрузка на память определяется по количеству свободной памяти, зарезервированной памяти, кэшированной памяти и коэффициенту подкачки.

Физическая память. Объем установленной оперативной памяти.

Используемая память. Объем используемой оперативной памяти. Справа показано, куда выделена память.

Память приложений. Объем памяти, используемый приложениями.

Зарезервированная память. Память, необходимая для работы системы. Эта память не может быть кэширована и должна оставаться в оперативной памяти, поэтому она недоступна другим приложениям.

Сжатый. Объем памяти, который был сжат для освобождения дополнительной оперативной памяти.

Когда объем доступной памяти компьютера заканчивается, он сжимает неактивные приложения в памяти, выделяя дополнительную память для активных приложений. Выберите столбец «Сжатая память», затем в столбце «Сжатая ВП» найдите приложение, чтобы просмотреть объем памяти, сжатой для этого приложения.

Кэшированные файлы. Размер файлов, кэшированных в неиспользуемую память для повышения производительности.

Эта память остается в кэше, пока не будет перезаписана, что может повысить скорость работы при следующем открытии приложения.

Использование своп. Объем места на загрузочном диске, используемого для перемещения неиспользуемых файлов в оперативную память и из нее.

Чтобы отобразить другие колонки, выберите меню «Вид» > «Колонки», затем выберите колонки для отображения.

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Check if your Mac needs more RAM in Activity Monitor

The Memory pane displays how much memory your Mac is using, how often it is swapping memory between RAM and your startup disk, and the amount of memory provided for an app and how much of it is compressed memory.

When you have free or unused memory, your computer performance does not necessarily improve. macOS obtains the best performance by efficiently using and managing all of your computer’s memory.

In the Activity Monitor app on your Mac, click Memory (or use the Touch Bar).

The Memory Pressure graph lets you know if your computer is using memory efficiently.

Green memory pressure: Your computer is using all of its RAM efficiently.

Yellow memory pressure: Your computer might eventually need more RAM.

Red memory pressure: Your computer needs more RAM.

If memory pressure is yellow, red, or has spikes, check to see if an app is using up memory and causing the memory pressure to increase. If you no longer need to have the app running, you should quit the app.

Your computer’s memory pressure is accurately measured by examining the amount of free memory available, the swap rate, and the amount of wired and file cached memory to determine if your computer is using RAM efficiently.

To learn how to add more RAM to your Mac, do one of the following, depending on your Mac model:

Choose Apple menu

> About This Mac, click Memory, then click Memory Upgrade Instructions.

Choose Apple menu

> About This Mac, click Support, then click Hardware Support.

Note: This option is only available on Mac computers with upgradable RAM.

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Understanding Compressed Memory on the Mac

If you’ve noticed that your Mac seems to have a bit more bounce in its performance since you installed OS X Mavericks, it may be because of the advances in memory management and the return of memory compression.

Information in this article applies to Macs running macOS Catalina (10.15) through OS X Mavericks (10.9).

Changes to How Mac Manages Memory

With the release of OS X Mavericks, Apple changed how the Mac managed memory. With the addition of memory compression, your Mac can now do more with less memory while maintaining or increasing performance. In older versions of OS X, memory usage was built around a standard memory management system. Apps requested an allocation of RAM, the system fulfilled the request, and the apps gave back the RAM when they no longer needed it.

The operating system took care of most of the work of keeping track of how much RAM was available and who was using it. The OS also figured out what to do if the amount of RAM needed wasn’t available, which could lead to adverse effects on the Mac’s performance as the system tried to make use of virtual RAM by swapping space on an SSD or hard drive.

What Is Compressed Memory?

Compressed memory isn’t something new or exclusive to Apple. Computing systems have been using various forms of memory compression for a long time. If you used Macs in the mid-’80s and early ’90s, you might remember products such as RAM Doubler from Connectix, which compressed data stored in RAM, effectively increasing the amount of free RAM available to the Mac.

Compressed memory utilities fell out of favor as computer makers and OS developers created better memory management systems. At the same time, memory prices declined. The other factor that made memory compression systems lose their popularity was the performance issue. Memory compression algorithms took a hefty chunk of processing power. While they let you get more done with less physical RAM, they tended to bog down your computer when they needed to compress or decompress memory.

Memory compression is making a comeback, primarily because of the advent of inexpensive multiple core processors. When the routines used for memory compression can be offloaded to one of many processor cores, you’re not likely to notice any performance hit when memory needs to be compressed or decompressed. It becomes merely a background task.

How Compressed Memory Works on a Mac

Memory compression on the Mac increases operating system and app performance by allowing better management of RAM resources. It also prevents or significantly reduces the use of virtual memory, which is the paging of data to and from Mac’s drive.

With OS X Mavericks and later, the OS looks for inactive memory, which is memory that isn’t currently in active use but still holds data that can be used by an app. This inactive memory compresses the data it’s holding, so the data takes up less memory. Inactive memory can be apps that are in the background and not being used. An example is a word processor that is open but inactive because you’re taking a break and reading about compressed memory. While you’re busy browsing the web, the OS is compressing the word processor’s memory, freeing up RAM for use by other apps.

When Does Memory Compression Occur?

The compression process isn’t active all the time. Instead, the OS checks to see how much free space is available in RAM. If there’s a significant amount of free memory, no compression occurs, even if there’s a lot of inactive memory.

As free memory is used up, the OS starts looking for inactive memory to compress. Compression starts with the oldest used data stored in memory and works its way forward to ensure that there is adequate free memory available. When the data in a compressed area of RAM is needed, the OS decompresses the data on the fly and makes it available to the app requesting it. Because the compression and decompression routines run concurrently on one of the processor cores, you’re unlikely to experience any performance loss while the compression or decompression occurs.

Limits of Memory Compression on Macs

There are limits to what compression can achieve. At some point, if you continue to launch apps or use memory-intensive apps that gobble up RAM, your Mac won’t have enough free space to function optimally. Just as in the past, the OS begins to swap inactive RAM data to your Mac’s drive. However, with memory compression, this is likely to be a rare occurrence for most users.

Even if the OS ends up swapping memory out to your drive, OS X’s memory management system takes advantage of the compressed inactive memory by writing the compressed data to full-length drive segments to increase performance and reduce wear on SSDs.

Activity Monitor and Memory Compression

Apple provided a nifty tool, the Activity Monitor, that could monitor how the Mac used RAM. While the Activity Monitor is still available, its memory monitoring capabilities have undergone a dramatic change that mimics the way a Mac is better able to make use of RAM through the use of compressed memory.

You can monitor how much memory the Mac is compressing by using the Memory tab in Activity Monitor. Compressed memory displays in the Memory Pressure graph, which indicates how actively the OS is involved in compressing RAM data. The graph turns from green (little pressure) to yellow (significant pressure), and finally to red, when there isn’t enough RAM space, and memory has to be swapped out to the drive.

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Use Activity Monitor to Track Mac Memory Usage

Track memory usage to know when your Mac needs more RAM

It can be challenging to get your head around your Mac’s memory usage. The Activity Monitor utility can help, especially when it’s time to consider whether you need to upgrade your computer’s RAM.

Activity Monitor has been part of all macOS and most OS X operating systems for the Mac, but it’s current format was introduced in OS X Mavericks (10.9). This article contains information that applies to Activity Monitor in macOS 10.15 through OS X Mavericks (10.9), as well as information for earlier versions of OS X.

Mac Activity Monitor

The Activity Monitor is a free system utility that comes on all Macs. It includes tabs for five areas that illustrate how applications and other processes affect your computer. The tabs are:

• CPU: Shows the effects of processes on CPU activity
• Memory: Monitors usage of memory including the RAM physical memory
• Energy: Indicates the amount of energy used by each app
• Disk: Shows the amount of data read from and written to the disk
• Network Usage: Indicates which processes are sending or receiving data over your network

The Memory tab of Activity Monitor is where you monitor and manage memory usage on your Mac.

Activity Monitor Memory Chart (OS X Mavericks and Later)

When Apple released OS X Mavericks, it introduced the Memory Pressure chart in Activity Monitor, along with compressed memory, a significant change in how the operating system manages memory. Memory compression makes the most of available RAM by compressing the data stored in RAM instead of paging memory to virtual memory, a process that can significantly slow down the performance of a Mac.

In addition to the use of compressed memory, Mavericks brought changes to Activity Monitor and how it presents memory usage information. Instead of using the pie chart that appeared in earlier versions of OS X to show how memory is divided, Apple introduced the Memory Pressure chart as a way to express how much memory your Mac compresses to provide free space for other activities.

Memory Pressure Chart

The Memory Pressure chart appears at the bottom of the Memory tab in the Activity Monitor window. It indicates the amount of compression being applied to RAM, as well as when paging to disk occurs when compression isn’t sufficient to meet the demand by apps to allocate memory.

The Memory Pressure chart displays in three colors:

• Green: Indicates no compression
• Yellow: Shows when compression is occurring
• Red: Compression has reached its limits, and paging to virtual memory has started

In addition to the color that indicates what’s occurring within the memory management system, the height of the bars reflects the extent of compression or paging that is ongoing.

Ideally, the Memory Pressure chart should remain in the green, indicating that no compression is occurring and that you have adequate available RAM for the tasks that need to be performed. When the chart begins to show yellow, it indicates that cached files that are no longer active but still have their data stored in RAM are being compressed to create enough free RAM to assign to the apps requesting an allocation of RAM.

The memory compression requires some CPU overhead, but this small performance hit is minor and usually not noticeable to the user.

When the Memory Pressure chart begins to display in red, there’s no longer enough inactive RAM to compress, and swapping to disk (virtual memory) is taking place. Swapping data out of RAM is a much more process-intensive task and is usually noticeable as an overall slowdown in your Mac’s performance.

How to Tell When You Need RAM

The Memory Pressure chart makes it easyto tell at a glance if your Mac needs additional RAM.

• If the chart is green most of the time, your Mac doesn’t need additional RAM.
• If your chart is a mix yellow and green, your Mac is making the best use of the available RAM without having to page data to the drive. You’re seeing the benefit of memory compression and the Mac’s ability to use RAM economically to keep you from having to add more RAM. If the chart is usually yellow and seldom green, you may need RAM in the near future.
• If the chart is in the red frequently or for an extended time, your Mac would benefit from more RAM. If it only peaks into red when you open an app but otherwise stays in yellow or green, you probably don’t need more RAM, although you may want to cut back on how many apps you keep open at the same time.

Although the Activity Monitor Dock icon can be configured to display some stats in the Dock, compressed memory is not one of them. You must open the application window to view the Memory Pressure chart.

Activity Monitor Memory Chart (OS X Mountain Lion and Earlier)

Earlier versions of OS X before OS X Mountain Lion used an older style of memory management that doesn’t make use of memory compression. Instead, it tries to free up memory that it previously allocated to apps, and then—if needed—to page memory to your drive as virtual memory.

Activity Monitor Pie Chart

The Activity Monitor pie chart shows four types of memory usage: Free (green), Wired (red), Active (yellow), and Inactive (blue). To understand memory usage, you need to know what each memory type is and how it affects available memory.

• Free. This is the RAM in your Mac that it isn’t currently using and can assigned to any process or application that needs all or some portion of the available memory.
• Wired. Your Mac assigns Wired memory to its internal needs and the core needs of applications and processes you’re running. Wired memory represents the minimum amount of RAM your Mac needs at any point in time to keep running. You can think of this as memory that’s off-limits for everything else.
• Active. Memory currently in use by applications and processes on your Mac, other than the special system processes assigned to Wired memory, is Active memory. You can see the Active memory footprint grow as you launch applications or as currently running applications need and grab more memory to perform a task.
• Inactive. Inactive memory is no longer required by an application but the Mac hasn’t yet released to the Free memory pool.

Understanding Inactive Memory

Most of the memory types are straightforward. The one that trips up people is Inactive memory. Individuals often see a large amount of blue in the memory pie chart and think their Mac has memory issues. This leads them to think about adding RAM to boost their computer’s performance, but in reality, Inactive memory performs a valuable service that makes your Mac snappier.

What Is Inactive Memory?

When you quit an application, OS X doesn’t free all the memory the application used. Instead, it saves the application’s startup state in the Inactive memory section. Should you relaunch the same application, OS X knows it doesn’t need to load the application from your hard drive because it’s already stored in Inactive memory. As a result, OS X redefines the section of Inactive memory that contains the application as Active memory, which makes relaunching an application a quick process.

How Does Inactive Memory Work?

Inactive memory doesn’t remain inactive forever. OS X could start using that memory when you relaunch an application. It also uses Inactive memory if there’s not enough Free memory for an application’s needs.

The sequence of events goes something like this:

• When you launch an application, OS X checks to see if it’s stored in Inactive memory. If it is, that memory is reassigned as Active and the application launches.
• If the application isn’t in Inactive memory, OS X carves out an appropriate chunk of Free memory for the application.
• If there isn’t enough Free memory, OS X releases some Inactive memory to fill the application’s needs. Releasing Inactive memory removes one or more of the cached applications from the Inactive memory pool, forcing a longer launch time for those applications.

So, How Much RAM Do You Need?

The answer to that question is usually a reflection of the amount of RAM your version of OS X needs, the type of applications you use, and how many applications you run concurrently. However, there are other considerations. In an ideal world, it would be nice if you didn’t have to raid Inactive RAM often. This provides the best performance when launching applications repeatedly while maintaining enough Free memory to meet the needs of any currently running applications. For example, each time you open an image or create a new document, the related application needs additional Free memory.

To help you decide if you need more RAM, use Activity Monitor to watch your RAM usage. If Free memory falls to the point where Inactive memory is being released, you may want to add more RAM to maintain maximum performance.

You can also look at the Page outs value at the bottom of Activity Monitor’s main window. This number indicates how many times your Mac has run out of available memory and used your hard drive as virtual RAM. This number should be less than 1000 during a full day’s use of your Mac.

You don’t need to add more RAM if your Mac is performing to your expectations and needs.

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