Sorry for the wrong info. I can only trace the code allocating twice the
pages for SEQUENTIAL. I can't trace the code that discards the allocated
pages...
AFAIK, there are 2 options if discard doesn't happen automatically
1. SEQUENTIAL + NOREUSE
This can be issued as a single-call, but I thin
On Wed, May 21, 2014 at 10:50 AM, Ravikumar Govindarajan
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
>
>
>
> 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...
Well, that option is too late? Like, say I read in the N 1 GB files
to merge, then I call DONTNEED once the merge is done, but by then the
pages f
On Wed, May 21, 2014 at 8:20 AM, Ravikumar Govindarajan
wrote:
> Great blog and lucid explanation
>
> I think things have changed in recent kernel versions. I am no expert, but
> could see some code related to this here
> http://lxr.free-electrons.com/source/mm/fadvise.c?v=3.14
That looks promisi
Great blog and lucid explanation
I think things have changed in recent kernel versions. I am no expert, but
could see some code related to this here
http://lxr.free-electrons.com/source/mm/fadvise.c?v=3.14
O_DIRECT will be terrible drag no? Will a battery-backed disk cache help
here?
We are usin
You're right, segment merges can be catastrophic to ongoing searches.
I explored the problem here:
http://blog.mikemccandless.com/2010/06/lucene-and-fadvisemadvise.html
but a lot has changed since then...
SEQUENTIAL is probably best (if the OS implements it; I think the
Linux kernel has improved h
Is it a good idea to use FADVISE_DONTNEED/MADVISE_DONTNEED flags during
segment merge reads?
Buffer-Cache contains critical data belonging to searches. A segment-merge
has the potential to disturb the cache no?
--
Ravi
