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From Michael McCandless <luc...@mikemccandless.com>
Subject Re: fadvise/madvise during segment-merges....
Date Wed, 21 May 2014 17:03:29 GMT
On Wed, May 21, 2014 at 10:50 AM, Ravikumar Govindarajan
<ravikumar.govindarajan@gmail.com> wrote:
>>
>> But does that mean SEQUENTIAL will evict the
>> page once we're done reading it?
>
>
> Yes, looks like it does evict the pages once read completes...

That's great news, we need to re-test it.

> Let me elaborate a bit more
>
> I have numerous unsorted segments with very less sizes and fewer sorted
> segments with biggish sizes. Merge-Policy will segregate these 2
>
> The bigger sorted-segments always merge within themselves using SMP &
> SEQUENTIAL advise. It should be helpful in this case no?
>
> Smaller unsorted segments also merge within themselves using SMP. But since
> the segment-sizes are very less, the effect on buffer-cache must be
> negligible. I feel there is no need to advise in this case...
>
> There are also sneaky ways to
>> invoke some of these OS-level APIs without using JNI

Ahh, OK, yes for the large already-sorted segments, these will be
sequential reads to the OS.

Mike McCandless

http://blog.mikemccandless.com

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