ReHypar: A Recursive Hybrid Chunk Partitioning Method Using NAND-Flash Memory SSD

Algorithm 1

The procedure for the file allocation in ReHypar.

ALLOCATE  (input: a new file 𝑓)

(1)  if (𝑓≥ s) {

(2)   assign m (𝑓/𝑠) number of clean extents to 𝑓;

(3)   // let 𝐸 be the last extent allocated to 𝑓 and pos be the last block position.

(4)   call MAP(pos);

(5)   // let 𝑖 and 𝐿 be the chunk index and level where the next file allocation takes place.

(6)   connect 𝐸 to the linked list associated to chunk 𝑖 in 𝐿

(7) }

(8)  else  {

(9)  𝑆 = the first extent connected to each linked list in 𝐿;

(10)  among extents in 𝑆, choose an extent 𝐸 in which the unused space beginning

     from chunk 𝑖 is at least 𝑓 and the ratio of 𝑑 to 𝑡 is the minimum;

(11)  assign 𝑓 to 𝐸, starting from chunk 𝑖;

(12)  call MAP to calculate the next chunk where the next file allocation occurs;

(13)  // let 𝑖 and 𝐿 be the outputs of MAP.

(14)  connect 𝐸 to the linked list associated to chunk 𝑖 in 𝐿;

(15) }

MAP (input: the last block position pos allocated on E)

(1) compute 𝑘 such that 2^𝑘≤  pos<2^𝑘+1; 𝐿=0;

(2)  if (𝑘<log₂𝑣) {

(3)  // return the next chunk index and partitioning level.

(4)  𝑖=𝑘+1; return

(5) }

(6)  while (𝑘≥log₂𝑣) {

(7)  L++;

(8)  find 𝑗 such that 2^𝑗≤pos−start(𝑐^𝐻_𝐿)<2^𝑗+1;

(9)  if (𝑗<log₂𝑣) {

(10)    // return the next chunk index and partitioning level.

(11)    𝑖=𝑗+1; return

(12)  }

(13)  𝑘=𝑗;

(14) }