Mailinglist Archive: opensuse (982 mails)

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Re: [opensuse] disk cache
On 09/22/2014 08:31 AM, Roger Oberholtzer wrote:
The cache seems to be
filling up

That is GOOD! The kernel uses memory not used by applications
to cache things regarding file system reads/writes.
I don't see anything wrong with that. In fact, I personally
don't have fast SSDs, but rather bought 20G of memory. The
processes are only using ~2-8G, so everything else can be - and
in fact - is used as cache.
I doubt that for my case an SSD could be faster than RAM.
I admit this is an extreme attitude, but it adheres to the
very old yet still valid statement: "to make a UNIX system faster,
add more RAM". It's not that UNIXoide and thus Linux kernels need
more memory, but if it's there, then they'll use it very efficiently.

Therefore: simply trust your kernel (unless you have modified
the cache settings into an disadvantageous range).

Regarding writing to the drop_cache pseudo file: I use it only
when I want to measure the performance to simulate a "cold" cache,
i.e., when the program and data needed for a process is not yet
in memory but has to be read from disk. A subsequent run may be
faster in magnitudes, and therefore can't be taken for comparison.

Have a nice day,
Berny
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