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From Dmitriy Setrakyan <dsetrak...@apache.org>
Subject Re: Reconsider default WAL mode: we need something between LOG_ONLY and FSYNC
Date Thu, 12 Apr 2018 23:48:20 GMT
On Thu, Apr 12, 2018 at 9:45 AM, Ivan Rakov <ivan.glukos@gmail.com> wrote:

> Dmitriy,
> fsync() is really slow operation - it's the main reason why FSYNC mode is
> way slower than LOG_ONLY.
> Fix includes extra fsyncs in necessary parts of code and nothing more.
> Every part is important - at the beginning of the thread I described why.
> 20% slow in benchmark doesn't mean than Ignite itself will become 20%
> slower. Benchmark replays only "data loading" scenario. It signals that
> maximum throughput with WAL enabled will be 20% slower. By the way, we
> already have option to disable WAL in runtime for the period of data
> loading.
Ivan, I get it, but I am sure that you can do more things in parallel. Do
we wait for the fsync call to complete? If yes, do we have to wait? Are
there other performance optimizations you can add, considering that we are
in LOG_ONLY or BACKGROUND modes and disk writes may be delayed.


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