RE: why swap at all?

[Buddy Lumpkin]

>> Couple that with the fact that there are many pte's pointing at the same
>> physical page (shared page) in many cases where many processes 
>>
>> are running
>> on the system. Because all of the references to that page must be removed
>> before the page can be evicted, there are some absolute 
>> limitations in the
>> rate that pages can be evicted from memory as the number of processes
>> running on the system and the total amount of memory increases.
>> 

> This is still many orders of magnitude faster than filling the page
> from disk, and you typically don't reclaim much of mapped memory anyway.

This discussion went broke-minded again. Your still picturing that single
IDE hard drive in your workstation and im talking about big iron, large
databases, etc.. where the total amount of aggregate disk I/O is completely
limited by the rate you can evict pages from the pagecache.

Picture 6 to 7 fibre channel cards with over 70% utilization during peak
usage times connected to a large EMC storage array with 64GB of non-volatile
cache.

--Buddy

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/