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https://issues.apache.org/jira/browse/IGNITE-5884?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ivan Rakov reassigned IGNITE-5884:
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Assignee: Ivan Rakov
> 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
> Assignee: Ivan Rakov
> Fix For: 2.2
>
> Attachments: CpBenchmark.java, iostat.log, ssdlab.log
>
>
> 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
> Article by Emmanuel Goossaert describing why writing less than a page is
> сounterproductive:
> http://codecapsule.com/2014/02/12/coding-for-ssds-part-3-pages-blocks-and-the-flash-translation-layer/
> 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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