Re: Cache digests

From: Alex Rousskov <>
Date: Fri, 24 Jul 1998 08:54:54 -0600 (MDT)

On Fri, 24 Jul 1998, Christian Khoury wrote:

> 1) maybe i missed something, but where can i change the frequency of
> requests for peer cache digests. Is it hard coded ? what is it by
> default ?

Digests are requested when they expire. Digests expiration depends on the
builder of the digest. For the local (your) digest, there is a hard coded
rebuild period that defaults to 1 hour. You can change it by modifying the
StoreDigestRebuildPeriod constant in store_digest.c. I also recommend that
you keep StoreDigestRewritePeriod in sync with StoreDigestRebuildPeriod.

Moving these and other hard coded variables into squid.conf is on my to-do
list as well as making the refresh algorithm smarter and customizable.

Note that it it does not hurt to requests digests more often (and it
sometimes happens) because a tiny 304 reply will be returned until the time
the digest is really different.
> 2) can anyone point to me where i can find the amount of memory used by
> a digest (disk and memory) ? (i know it should be in cachemgr.cgi)

"Store Digest" item will show you the size (memory == disk) for your local
digest (first line).

store digest: size: 1378462 bytes
         entries: count: 507424 capacity: 2205538 util: 23%
         deletion attempts: 0
         bits: per entry: 5 on: 1853455 capacity: 11027696 util: 17%
         bit-seq: count: 3085479 avg.len: 3.57
         added: 507424 rejected: 1587501 ( 75.78 %) del-ed: 0
         collisions: on add: 0.03 % on rej: 0.02 %

In "Peer Selection Algorithms", you will find similar info for all your

"Cache Digest and ICP blob" has both local and peer stats.

Received on Fri Jul 24 1998 - 07:56:16 MDT

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