ADB Overview

Regarding this project, I am explaining in detail just about memory information through ADB within the mobile device,

I have connected my Samsung Galaxy S21 FE and enabled the developer permissions

To access developer permission we have to press the build number multiple times

As soon as we enter the Developer options, search for USB debugging

And enable it.

Now open command prompt in the PC

then start executing the ADB commands.

One of such command is "/proc/meminfo"

The parameters within it are explained including the basic understanding and Idea aboout ADB and the components and the working process

 ADB means that Andriod Debug Bridge ADB is a command-line tool Allows for debugging, testing and monitoring of Andriod apps and devices Supports multiple devices and emulators simultaneously

Components of ADB:

Client -> Sends Commands 

 Daemon-> Runs Commands

 Server ->Manages Commands

Setting up ADB:

Install Andriod SDK and Platform Tools

 Enable USB Debugging on Device 

 Connect USB debugging 

 Verify ADB Connection

Memory Information using ADB:

So, I'll try my level best to convey some information about these parameters.

• MemTotal:

   - Definition: The total amount of physical RAM available in the system.

   - Purpose: Indicates the maximum amount of physical memory the system can use.

   - Example: `MemTotal: 16384000 kB` (where 16384000 kB is approximately 16 GB of RAM).

•  MemFree:

   - Definition: The amount of physical RAM that is currently unused and available for new processes.

   - Purpose: Provides a snapshot of free memory at a given moment.

   - Example: `MemFree: 2048000 kB` (where 2048000 kB is approximately 2 GB of free RAM).

•  MemAvailable:

   - Definition: An estimate of how much memory is available for starting new applications without swapping.

   - Purpose: A more accurate measure than `MemFree` for determining available memory because it includes both free memory and reclaimable memory (e.g., caches and buffers).

   - Example: `MemAvailable: 8192000 kB` (where 8192000 kB is approximately 8 GB of available RAM).

• Buffers:

   - Definition: Memory used by the kernel to buffer I/O operations, such as file system metadata.

   - Purpose: Helps speed up disk and network I/O by storing temporary data.

   - Example: `Buffers: 1024000 kB` (where 1024000 kB is approximately 1 GB of buffer memory).

• Cached:

   - Definition: Memory used for caching file data to improve read performance.

   - Purpose: Reduces disk I/O by keeping frequently accessed file data in RAM.

   - Example: `Cached: 6144000 kB` (where 6144000 kB is approximately 6 GB of cached memory).

•  SwapCached:

   - Definition: Memory that was swapped out to disk but has since been brought back into RAM and is still in the swap area.

   - Purpose: Allows the system to quickly reclaim this memory if needed, as it is still in the swap cache.

   - Example: `SwapCached: 512000 kB` (where 512000 kB is approximately 500 MB of swap-cached memory).

• Active:

   - Definition: Memory that is currently in use or has been recently used by processes and is likely to be accessed again soon.

   - Purpose: Indicates memory that is "hot" and less likely to be reclaimed.

   - Example: `Active: 10240000 kB` (where 10240000 kB is approximately 10 GB of active memory).

•  Inactive:

   - Definition: Memory that is not actively being used but is still in RAM.

   - Purpose: Can be reclaimed if needed, includes memory that may be used for file caching or memory-mapped files.

   - Example: `Inactive: 4096000 kB` (where 4096000 kB is approximately 4 GB of inactive memory).

Understanding these metrics helps in monitoring and managing system performance and memory usage. They provide insights into how memory is being utilized, which can be useful for diagnosing performance issues and optimizing resource allocation.

1. Swap Cached:

   - Definition: Memory pages that have been swapped out to disk but are still cached in RAM.

   - Purpose: Helps improve performance by keeping frequently accessed swapped-out pages in memory for quicker retrieval.

2. Active & Inactive (Anon):

   - Active: Memory pages that are currently in use or recently used by processes and are likely to be accessed again soon.

   - Inactive (Anon): Memory pages that are not currently being used by processes but are still held in memory. These pages may be reclaimed if memory is needed.

3. Mlocked:

   - Definition: Memory pages that are locked in physical memory and cannot be swapped out to disk.

   - Purpose: Ensures that critical memory pages remain in RAM to avoid performance degradation or security risks.

4. Rbin & Rbinpool:

   -Rbin: Memory pages that contain executable code or read-only data.

   - Rbinpool: Pool of memory pages containing reusable executable code or read-only data.

5. Zeroed Free:

   - Definition: Memory pages that are marked as free (available for allocation) and have been zeroed out (all bits set to zero).

   - Purpose: Provides clean memory for new allocations, ensuring that sensitive data from previous use is not exposed.

6. Dirty:

   - Definition: Memory pages that have been modified since they were last synchronized with their corresponding disk storage.

   - Purpose: Indicates that changes have been made to the memory pages and they need to be written back to disk to maintain data consistency.

7. Write Back:

   - Definition: Process of asynchronously writing modified memory pages back to disk storage.

   - Purpose: Improves performance by allowing processes to continue without waiting for disk writes to complete, as writes are buffered and performed in the background.

8. Anon Pages:

   - Definition: Memory pages that are not associated with any particular file or device and are typically used for anonymous memory allocations by processes.

   - Purpose: Provides memory for dynamic data structures, heap allocations, and anonymous memory mappings.

9. Mapped:

   - Definition: Memory pages that are mapped to files or devices, allowing processes to access their contents directly.

   - Purpose: Enables efficient I/O operations by mapping files into memory, reducing the need for explicit read/write operations.

10. Shmem (Shared Memory):

    - Definition: Memory pages that are shared between multiple processes, allowing them to communicate and share data efficiently.

    - Purpose: Facilitates inter-process communication (IPC) and data sharing, particularly for closely cooperating processes or system services.

Understanding these memory states and categories is crucial for system administrators, developers, and performance analysts to optimize system performance, diagnose memory-related issues, and ensure efficient memory utilization in operating systems.

These terms relate to various aspects of memory management and allocation in an operating system. Let's explore each one:

1. K Reclaimable:

   - Represents memory that the kernel can potentially reclaim for other purposes.

   - Includes cached data and metadata that can be freed if needed.

2. Slab:

   - A memory management mechanism in the Linux kernel for managing the kernel's memory caches.

   - Improves performance by reusing memory allocations for frequently used data structures.

3. SReclaimable:

   - Part of the Slab cache that holds memory that is both reclaimable and able to be shared.

   - Can be freed under memory pressure and includes items such as cached file data.

4. Kernel Stack:

   - Memory allocated to store the execution context of a thread when it's executing in kernel mode.

   - Each thread typically has its own kernel stack.

5. Page Tables:

   - Data structures used by the operating system's memory management unit (MMU) to translate virtual memory addresses to physical memory addresses.

   - Essential for managing memory mappings and ensuring memory protection.

6. NFS_Unstable:

   - Represents data that has been written to an NFS (Network File System) server but has not yet been confirmed as written.

   - Typically used to ensure data consistency in network file operations.

7. Bounce:

   - Refers to a technique used in certain hardware configurations to deal with memory addressing limitations.

   - Involves bouncing data between different memory regions to accommodate address space constraints.

8. Write Back Tmp:

   - Temporary storage used for write-back operations, such as buffering data before it's written back to disk.

   - Helps optimize disk I/O by allowing writes to be batched and deferred.

9. Commit Limit:

   - Represents the maximum amount of memory that the system can allocate without exceeding available resources.

   - Determines the system's ability to fulfill memory allocation requests.

10. Committed_As:

    - Indicates the total amount of memory (in kilobytes) that has been allocated to processes.

11. Vmalloc:

    - Refers to virtual memory allocated dynamically by the kernel for various purposes, such as kernel modules and device drivers.

12. PerCPU:

    - Memory allocation technique in which each CPU is assigned its own separate memory area.

    - Reduces contention for shared memory resources among CPUs.

13. Vmalloc Chunk:

    - Represents a contiguous block of virtual memory allocated using vmalloc.

14. Hugepages:

    - Large memory pages that can improve performance by reducing the overhead associated with managing smaller memory pages.

15. CMA Total:

    - Represents the total amount of memory reserved for Contiguous Memory Allocation (CMA), which is used for DMA (Direct Memory Access) operations in embedded systems.

16. File PMD Mapped:

    - Refers to memory mapped for a file, using a page size managed by the Page Mapping Directory (PMD).

These terms provide insights into different aspects of memory management and allocation in an operating system, helping administrators and developers understand and optimize memory usage.

For Any doubts, suggestioons and queries , Reach me through the contact details mentioned within the blog. Thanks for reading!