In order to give full play to the characteristics of SSD, and it fit best engine is the way to append engine. Such additional writing can facilitate internal SSD can find a plurality of consecutive physical page, to reduce internal logical addresses to physical address translation index update. But the same time, relatively flat-type engine is stored, is written at the end of the file will be faster. This design of the GC's proposed higher requirements. Here are a few suggestions personal summary.
Covering part of the write data as quickly as possible trim
In the SSD is a relatively light interior trim operations, but the more trim, the interior idle Page will increase more, which is conducive to new write requests quickly find a free block. Therefore, it is obvious gains. GC strategy is relatively simple, the first periodic statistical data segments which need to be removed, and then delete together. Obviously this approach and update the index at the time of writing the cover
on deleting data comparison, it is a lot slower.
The frequency adjustment system load GC
The general principle is as follows:
The larger the IO load, GC has done more slowly, to avoid bringing too much impact on the overall bandwidth is;
the smaller user IO load, GC has done more frequently, take full advantage of SSD leisure bandwidth. ;