What is zram in android

Android 4. ZRAM can be seen as a virtual disk using memory as a swap partition for Linux. Unlike ordinary ramdisk, zRAM will compress the stored content in real time to increase the actual capacity. I have tried Android with swap partitions. The slowness of the swap is not as good as not to open it. On Android, there is no swap! So a kind of swap in memory.

However, the CPU has to work in more because they compress the data has or unpack again when they are needed. The advantage clearly lies in the speed. Since the swap partition in RAM is much faster than this is a swap partition on a hard drive.

In itself a great thing. Compressed by the "enlarged" so to speak of the available memory. The S2 has 1GB but the rich, and more than. There must not be artificially pushed up to 1. After you activate the ZRAM also has 2 disadvantages. The encoding and decoding using CPU time, which in turn has higher power consumption. For devices with too little RAM so it makes perfect sense.

But who shoots the S2 already be fully complete RAM and then still need more? Sign up to join this community. Advanced Concepts. Device Manager. Device setup. Evaluating Performance. Feature Implementation. Dynamic Partitions. Android kernel 4. Stop cached processes if they're about to be uncached, and too large. Don't allow large services to put themselves back into the A Services classification so they can't cause the launcher to be stopped. Stop processes even ordinarily unstoppable ones such as the current IME that get too large in idle maintenance.

Serialize the launch of background services. Preloaded dex caches in Dalvik saved several megabytes. Validated JIT-off option saves up to 1. Reduced per-process font cache overhead. Procstats Added a developer option to show memory state and app memory usage ranked by how often they run and the amount of memory consumed. Memory tracking Added memtrack HAL to track graphics memory allocations, additional information in dumpsys meminfo, clarified summaries in meminfo for example, reported free RAM includes RAM of cached processes, so that OEMs don't try to optimize the wrong thing.

A high value will increase the amount of memory that the kernel tries to keep free, reducing allocation time and causing the lowmemorykiller to kill earlier.

Overrides the default value chosen by ActivityManager based on screen size. A positive value will increase the amount of memory that the kernel tries to keep free, reducing allocation time and causing the lowmemorykiller to kill earlier.

Directly added to the default value chosen by ActivityManager based on screen size. A low value will keep more processes in memory but may cause thrashing if set too low. Overrides the default value chosen by ActivityManager based on screen size and total memory for the largest lowmemorykiller bucket, and scaled proportionally to the smaller buckets.

Directly added to the default value chosen by ActivityManager based on screen size and total memory for the largest lowmemorykiller bucket, and scaled proportionally to the smaller buckets. Android handles swap to zram at several levels. When using zram, the incremental cost of reading one page at a time is negligible and can help if the device is under extreme memory pressure.

To read only one page at a time, add the following to your init. X The memory cgroups are automatically configured at boot time if the feature is enabled in the kernel.

If memory cgroups are available, ActivityManager marks lower-priority threads as being more swappable than other threads. If memory is needed, the Android kernel starts migrating memory pages to zram swap, giving a higher priority to the memory pages that have been marked by ActivityManager. Carveouts, Ion, and contiguous memory allocation CMA On low-memory devices, it's important to be mindful about carveouts, especially those that aren't fully used, such as a carveout for secure video playback.

Use the PNG format for assets, especially when they have transparent areas. Don't enable code that writes Parcel data to disk and reads it later. Use SSP filtering instead of subscribing to every package installed. Ideally, these apps shouldn't be running at all. These add memory load to the system. However, many of these apps run for good reasons. The size of pss is an important part of their memory load. Track pss to watch for these processes getting too large. TOP The process the user is currently interacting with.

These processes can be freely killed at any time and recreated if needed. The memory state normal, moderate, low, critical is computed based on how many of these processes the system is running.

The key metric for these processes is the pss.