Ivan Rakov created IGNITE-5884:
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             Summary: Change default pageSize of page memory to 4KB
                 Key: IGNITE-5884
                 URL: https://issues.apache.org/jira/browse/IGNITE-5884
             Project: Ignite
          Issue Type: Improvement
          Components: persistence
            Reporter: Ivan Rakov
             Fix For: 2.2


Checkpoint write speed is suboptimal with default 2K page on most UNIX-driven 
enviroments with SSD disk. There are several reasons for this:
1) Page size of linux page cache is 4k by default on most kernels (you can 
check yours by "getconf PAGE_SIZE" command). With 2k random writes 
vm.dirty_ratio threshold is reached two times faster than with 4k random writes.
2) Most SSD manufacturers don't reveal actual disk page size, but they 
recommend to write at least 4k at once. Also, 4k blocks are used during 
benchmarking SSD random writes. Related question: 
https://superuser.com/questions/1168014/nvme-ssd-why-is-4k-writing-faster-than-reading
I've prepared a checkpoint emulation benchmark (code and results attached). Run 
on production-level hardware (CentOS, 100 GB RAM, total LFS size is 100GB, 
vm.dirty_ratio=10) showed that checkpointing with 4k pages is much more 
efficient than with 2k.
*Important: backwards compatibility must be ensured with LFS files created with 
old 2k default page size.*



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