| 3 | 3 | Traditional xen-based systems track memory updates by keeping evidence of the dirty pages at each migration epoch. In [http://nss.cs.ubc.ca/remus/ Remus] and also our previous work, [wiki:LLM LLM], they use the same page size as Xen (for x86, this is 4KB), which is also the granularity for detecting memory changes. However, when running computational-intensive workloads under [wiki:LLM LLM] system, the long downtime performance becomes unacceptable. [wiki:FGBI FGBI] (Fine-Grained Block Identification) is a mechanism which uses smaller memory blocks (smaller than page sizes) as the granularity for detecting memory changes. [wiki:FGBI FGBI] calculates the hash value for each memory block at the beginning of each migration epoch. At the end of each epoch, instead of transferring the whole dirty page, [wiki:FGBI FGBI] computes new hash values for each block and compares them with the corresponding old values. Blocks are only modified if their corresponding hash values don’t match. Therefore, [wiki:FGBI FGBI] marks such blocks as dirty and replaces the old hash values with the new ones. Afterwards, [wiki:FGBI FGBI] only transfers dirty blocks to the backup host. |
