Re: mmap vs fs cache

[Howard Chu <hyc@symas.com>]

Jan Kara wrote:
> On Fri 08-03-13 12:04:46, Howard Chu wrote:
>> The test clearly is accessing only 30GB of data. Once slapd reaches
>> this process size, the test can be stopped and restarted any number
>> of times, run for any number of hours continuously, and memory use
>> on the system is unchanged, and no pageins occur.
>    Interesting. It might be worth trying what happens if you do
> madvise(..., MADV_DONTNEED) on the data file instead of dropping caches
> with /proc/sys/vm/drop_caches. That way we can establish whether the extra
> cached data is in the data file (things will look the same way as with
> drop_caches) or somewhere else (there will be still unmapped page cache).

I screwed up. My madvise(RANDOM) call used the wrong address/len so it didn't 
cover the whole region. After fixing this, the test now runs as expected - the 
slapd process size grows to 30GB without any problem. Sorry for the noise.

-- 
   -- Howard Chu
   CTO, Symas Corp.           http://www.symas.com
   Director, Highland Sun     http://highlandsun.com/hyc/
   Chief Architect, OpenLDAP  http://www.openldap.org/project/

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