[squid-users] cache peer: hit, miss and reject

Hi.

Is there a way for a cache peer to reject a particular request from
squid via ICP opcode, other than ICP MISS?

In the current, scenario some url regex acls are passed trough our
custom cache peer. Both ICP HIT and MISS are used to put proper DSCP
mark back to the user via qos_flows parent-hit directive.

Now we want the cache peer to be able to reject some requests, thus
forcing squid to serve them directly. Two applications for this
feature:
1. The cache peer knows in advance the requested object is not
cacheable at all. No need of passing the request via second proxy -
extra CPU load, extra delay for the user, extra sockets, etc, etc..
2. We know that 50% of the objects in our cache never get requested
second time, thus only creating load on the system to store and later
to evict them. So we prefer to be able to cache on second, third,
etc... request without passing the first requests via the peer at all.
Why? Same reasons as above.... ICP is cheap enough for statistics and
decision making...

We've played with other ICP opcodes like ICP_OP_MISS_NOFETCH,
ICP_OP_DENIED, etc. without positive effect. Either the actual HTTP
requests keep coming or Squid assumes the cache peer is misconfigured
and flags it as a dead parent.

Any ideas how to resolve my issue and offload the cache peer by at
least 50% of the requests it servers currently?

Best,
Niki
Received on Tue Sep 03 2013 - 19:15:19 MDT