Re: Hot memory cache

[Henrik Nordstrom]

On Tue, 23 Nov 2004, Alex Rousskov wrote:
AFAIK, the memory cache in Squid 2.5 keeps objects fetched from the 
network and in-transit objects. The memory cache does not keep objects 
fetched from disk.
Correct.
In-transit objects purge cached memory objects if there is not enough 
space and may even exceed the configured memory cache size (the 
cache_mem directive).
Correct.
Only objects under certain configurable size can 
be kept in the memory cache. Please correct me if any of the above is 
wrong.
All are correct. At least for 2.5 and earlier.
Is the above still true in Squid 3? Has any functionality related to the 
memory cache changed?
I assume it is still the case, but haven't kept a very close eye on these 
matters yet.

It has been discussed a lot to separate the hot object cache from 
in-transit data, and it is certainly the correct thing to do. I do not 
think this has yet been done, but I may be wrong.

It may also be worth noticing that the "Cache Mem" in at least 2.5 and 
earlier is very inefficiently structured and scales very bad with object 
size.

Regards
Henrik

Hot memory cache

[Alex Rousskov]

Hello,
	AFAIK, the memory cache in Squid 2.5 keeps objects fetched 
from the network and in-transit objects. The memory cache does not 
keep objects fetched from disk. In-transit objects purge cached memory 
objects if there is not enough space and may even exceed the 
configured memory cache size (the cache_mem directive). Only objects 
under certain configurable size can be kept in the memory cache. 
Please correct me if any of the above is wrong.

Is the above still true in Squid 3? Has any functionality related to 
the memory cache changed?

We have a customer who may benefit from a true "hot" memory cache: a 
dedicated RAM space for storing recently requested objects (whether 
fetched from disk or from the network) and independent from in-transit 
objects. I am trying to understand the amount of work needed to 
implement a hot cache in Squid 2.5 and Squid 3.0. Any comment/advise 
is welcomed.

Thank you,
Alex.